IAWA Bulletin n.s., Vol. 13 (3),1992: 307-349

WOOD STRUCTURE OF THE ROSACEAE IN RELATION TO ECOLOGY, HABIT AND PHENOLOGY

by

Shu-Yin Zhang!, Pieter Baas! and Marinus Zandee2

Summary Twelve wood anatornical characters, to­ deae and Spiraeoideae are mainly shrubby; gether with broad parameters from ecology, the Maloideae and Prunoideae mainly arbores­ habit and phenology were subjected to simple cent. Phenology mainly influences ray size correlation analysis, path analysis and prin­ and composition and vessel diameter, but cipal component analysis, in a total sampie of does, in our sampIe, not influence ring-por­ over 470 specimens belonging to 271 species osity. of the Rosaceae from the entire distribution Most of the above trends are in accordance area of the farnily. The functional, develop­ with reports on other families or regional mental and systematic implications of the re­ floras. Part of the variation in vessel charac­ sulting relations are discussed. Based on the ters is interpreted as the result of functional present analysis of ecological trends and pre­ adaptation for efficient or safe hydraulic ar­ vious phylogenetic analysis, a tentative sce­ chitecture. nario for the evolution of the Rosaceae is A principal component analysis (PCA) offered. produces three more or less recognisable The four non-anatornical variables (viz. groups: the Maloideae, the Spiraeoideae p.p., macroclimate, moisture availability, habit, and together with the Rosoideae, and the Prunoi­ phenology) show dose mutual correlations. deae. The representatives of the QuiIIajeae Therefore, simple correlation analysis cannot (usually placed in the Spiraeoideae) are dis­ properly reflect intrinsic relations between tributed near the centre of the scatter plot in wood anatornical characters and ecological the Maloideae and Prunoideae. Ray features factors, habit and phenology, and sometimes and vessel element length appear to be the even is misleading. After standardising all most important characters giving rise to this data for the mutual correlations of the ecologi­ result. cal parameters, and habit and phenology, and Key words: Ecological, functional, develop­ the mutual dependencies of most wood ana­ mental wood anatomy, systematics, evo­ tornical characters, only a lirnited number of lution, Rosaceae, habit, phenology, ves­ significant correlations between the non-ana­ sels, rays, ring-porosity, crystals. tomical and wood anatornical parameters remain (Table 15). These correlations only Introduction explain a low proportion of the total variation The Rosaceae constitute a chiefly woody recorded (usually 3-10% for single ecological family with a wide ecological range (from factors). Macroclirnate affects vessel diameter mesic to dry habitats; from cold temperate to and the incidence of crystals. Moisture avail­ hot tropical regions), different kinds of habit ability influences vessel element length. Habit (from tall trees to shrubs, subshrubs, dim­ is mainly related to ring-porosity, vessel fre­ bers or herbs) and phenology (from decidu­ quency, vessel element length, vessel diam­ ous to evergreen), and a large wood anatorni­ eter, ray height and ray composition. It is cal diversity (Zhang & Baas 1992; Zhang also related to systematic position: the Rosoi- 1992). It is thus feasible to study wood struc-

1) Rijksherbarium/Hortus Botanicus, P.O. Box 9514, 2300 RA Leiden, The Netherlands. 2) Institute of Theoretical Biology, Kaiserstraat 63, 2311 GP Leiden, The Netherlands.

Downloaded from Brill.com10/07/2021 07:51:36AM via free access 308 IAWA Bulletin n.s., Vol. 13 (3),1992 ture in relation to different abiotic and biotic wood anatomical characters by assessing their factors (viz. ecology, habit, and phenology) dependence on ecological factors. in this family. As explained in the materials and methods A number of studies on the relations of seetion, the quality and degree of detail of the wood structure to ecology were reported with­ ecological information leaves much to be de­ in species (Van Buijtenen 1958; Denne 1971, sired for most species studied. An attempt to 1974,1976; Jenkins 1975; Nicholls & Wright answer the above questions can therefore be 1976; Zhang et al. 1988), in genera (Baas preliminary at best as far as the analysis of 1973; Car1quist 1982a; Dickison et al. 1978; ecological trends is concemed. Van der Graaff & Baas 1974; Van den Oever et al. 1981), in families (Baas & Zweypfen­ Materials and Methods ning 1979; Baas et al. 1988; Car1quist 1966, 1977b, 1978, 1982b, 1984b; Dickison & Materials Phend 1985; Rury 1985; Rury & Dickison Over 470 samples bel on ging to 271 spe­ 1984), and in regional floras (Baas & Carl­ eies of Rosaceae were quantified wood ana­ quist 1985; Baas & Schweingruber 1987; tomically. Over half of the samples were col­ Baas et al. 1983; Carlquist 1977a; Carlquist lected from China (see Zhang & Baas 1992), & Hoekman 1985), and some general eco­ the remaining samples were from different logical trends were established (for reviews parts around the world (see Zhang 1992). Of see Baas 1976, 1982, 1986; Carlquist 1975, the specimens studied, most are from sub­ 1980, 1988). Less attention, however, has tropieal and temperate regrons, while a limit­ been paid to habit in relation to wood struc­ ed number of specimens are from tropical ture (e.g., Baas & Zweypfenning 1979: Baas regions. & Schweingruber; Baas et al. 1983: Baas et al. 1984; Carlquist 1966, 1984b; Rury & Parameters analysed Dickison 1984). So far there are relatively few The present study, like many earlier stud­ reports on the correlations of phenology with ies of ecological wood anatomy, suffers from wood structure (e.g. Baas & Zhang 1986; insufficient ecological data. No ecologieal in­ Car1quist 1988; Chowdhury 1964). formation is available on the sampies from In the present study the diversity in vari­ the FHOw eollection. For the sampies from ous wood anatomie al characters in relation to China, the locality is usually known, but fur­ ecological factors (e.g. macroclimate and ther information (e.g., altitude, plant size, moisture availability), habit, and phenology water availability) is limited to certain sam­ will be analysed in order to answer the fol­ pIes (viz., the sampies from Zhongtiao and lowing questions: 1) How and to what extent Yunnan). Ecological information for the Chi­ is wood structure related to the rough ecolog­ nese samples was therefore based mainly on ical parameters analysed? 2) How and to what floristic literature (Wu 1980; Yu 1974, 1985, extent are various wood anatomical charac­ 1986). For the samples from Schweingruber, ters related to habit and phenology on the one Carlquist, and those from Israel, the relevant hand, and among themselves on the other? publieations (Baas & Schweingruber 1987: 3) How and to what extent are the effects of Carlquist & Hoekman 1985; Baas et al. 1983; macroclimate, moisture availability, habit and Fahn et al. 1986) have offered the necessary phenology on wood structure interrelated? ecological data. The eeological information 4) How and to what extent do the mutual de­ for the sampies from Dechamps was based pendencies of wood anatomical features af­ on the field data attached with the sampIes. feet the ecological trends? Wormation on phenology and habit was main­ Earlier studies on the wood anatomie al di­ Iy based on Mabberley (1987), Hutehinson versity of the Rosaceae (Zhang & Baas 1992; (1964) and Yu (1974,1985,1986). In addi­ Zhang 1992) serve as a basis of our present tion to the limited and rough data mentioned study. In return, this study is also aimed at above, non-standard sampling may also have increasing our understanding of the system­ influeneed the quantitative data. However. it is arie and biologie al significance of various believed that these random sources of varia-

Downloaded from Brill.com10/07/2021 07:51:36AM via free access Zhang, Baas & Zandee - Wood structure of the Rosaceae 309 tion cannot have influenced the general re­ categories, however, were recognised in this sults appreciably. study. 1) Shrubs: here including shrubs, sub­ For the purpose of statistical quantifica­ shrubs, and perennial herbs; 2) Trees: woody tion, the following broad ecological and habit plants that attain a height of at least 7 m at categories were recognised: maturlty; 3) Intermediate-sized plants: large Macroclimatic zones - 1) Temperate spe­ shrubs to small trees. eies (occurrlng above 32° N or S latitude); 2) Subtropical species (occurring between In total, 12 wood anatomical characters 23° 30' and 32° N or S); 3) Tropical species were analysed. These characters include not (occurrlng between 23° 30' N or S; for the only qualitative but also quantitative ones: Chinese species, those occurrlng in Taiwan, ring-porosity, vessel frequency, percentage Hainan, southern Guangdong and southern of solitary vessels, (tangential) vessel diam­ Yunnan were treated as tropical elements). eter, vessel element length, length/diameter This classification ignores vast altitudinal (LID) ratio of vessel elements, multiple per­ variation within each region. forations, helical vessel wall thickenings, ray width, multiseriate ray height, ray composition Moisture availability - The same very and crystals. For definition and measurement rough and arbitrary categories as recognised of these features, see Zhang & Baas (1992). by Baas and Schweingruber (1987) for the All data analysed are given in Table 1. For European flora were adopted. 1) Dry: species statistical analysis, the qualitative parameters from physically and/or physiologically dry (viz., macroclimate, moisture availability, habitats; 2) Mesic: species from (relatively) habit, phenology, ring-porosity, the incidence moist habitats; 3) Normal: species from habi­ of multiple perforations, the incidence of heli­ tats intermediate in moisture availability be­ cal vessel wall thickenings, ray composition, tween the two above categories. and the incidence of crystals) were converted Habit- The Rosaceae include herbs, per­ to quantitative ones (see Table 1). Ring-por­ ennials, subshrubs, shrubs, climbers, large ous species were left out of the analysis of ves­ shrubs to small trees, to tall trees. Only three sei frequency and vessel diameter variation.

Table 1. Selected wood anatomical data of Rosaceae and the information on ecology, habit and phenology.! Genus I species I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sampie

Adenostoma fasciculatum Tw45889 2 2 2 176 91 23 230 10 0 0 5 0.4 2 0 FHOw 11226 2 3 208 72 42 0 0 2 0.4 2 0 Califomia 2 2 3 233 200 0 sparsifolium Tw 22802 2 3 64 94 43 270 6 0 6 0.5 3 0 Califomia 2 2 3 414 210 0 Alchemilla alpina 2 2 2 70 ISO 0 0 0 Amelanchier alnifolia 1 2 2 3 192 70 42 1 2 0.2 3 0 ovalis 1 1 2 3 320 82 25 410 16 I 2 0.2 3 pallida 2 2 1 2 3 380 0 sinica 2 2 3 290 79 27 630 23 2 0.2 3 0

1) The legend is given at the end of this table.

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(Table 1 continued) Genus / spccies / 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sampIe Amygdalus communis Israel 2 2 3 2 50 260 0 8 0.5 2 4342 1 2 2 38 200 0 7 1.0 2 Costa Brava 1 2 2 53 220 0 8 0.5 2 1 Mallorca 1 1 2 2 50 210 0 8 0.5 2 0 davidiana 1 1 s 2 26 270 0 4 0.8 I du leis 2 3 2 2 50 0 10 0.8 2 0 kansucnsis 2 3 2 2 68 320 0 5 0.5 2 korshinskyi 2 2 2 2 80 210 0 8 0.5 2 mira 2 2 3 2 38 310 0 5 0.7 2 I nana 2 2 35 320 0 5 0.5 2 0 pcrsica HEFw 3083 2 2 2 2 28 270 0 5 0.6 2 0 CAFw 15876 2 3 2 2 44 280 0 6 0.4 2 0 Anhui 2 2 2 2 28 290 I 4 0.7 2 1 CAFw 5716 I 2 3 2 54 280 0 6 0.7 2 0 CAFw 16900 I 3 2 2 30 390 I 6 0.5 2 0 Spain 2 2 2 35 240 0 7 0.6 2 0 CAFw 345 25 330 0 5 0.5 2 0 tri/oba CAFw 13721 2 2 32 330 0 3 0.4 2 I Liaoning I I 2 47 230 0 4 0.5 0 webbii 3 3 2 33 260 0 6 0.7 2 0 Armeniaca holosericea 2 2 2 31 260 0 8 0.6 2 mandshurica I 2 2 36 290 0 8 0.6 2 mume Anhui 2 2 2 2 49 230 0 5 0.5 0 CAFw 19345 2 3 3 2 I 37 310 0 5 0.7 2 0 Guangdong 2 3 3 2 3 110 52 36 290 8 0 8 0.6 2 0 mume var. alphandii 2 2 2 169 50 34 280 0 8 0.9 2 sibirica 2 3 2 30 290 0 8 0.4 2 vulgaris CAFw 13823 I 2 2 25 280 0 7 0.7 2 I HEFw 716 2 2 2 2 48 290 0 8 0.6 2 0 HEFw 2653 2 2 15 240 0 7 0.6 2 CAFw 588 I 2 2 32 240 0 8 0.5 2 HEFw 125 2 2 2 31 260 0 7 0.5 2 Liaoning I 2 48 250 0 5 0.6 FHOw 5099 3 2 17 280 0 8 0.5 2 S w itzerland (1) 2 2 54 250 0 8 0.5 2 1 Germany 2 I 2 50 280 0 8 0.5 2 0 Switzerland (2) 2 3 2 33 310 0 7 0.5 2 Cerasus avium FHOw 2797 2 2 3 176 23 48 310 6 0 4 0.5 2 I FHOw 11158 2 2 3 90 20 50 300 6 0 6 0.5 2 0 Bcrmgarten I 3 2 3 144 21 55 370 7 0 5 0.4 2 I 53 2 2 2 3 108 42 52 390 8 0 5 0.5 2 0 avium var. decumana 2 3 3 2 3 220 22 50 390 6 0 4 0.5 2 campanulata Guangdong 2 3 3 2 2 63 29 53 440 8 0 6 0.7 2 CAFw 13055 2 3 2 2 2 91 20 59 390 7 0 5 0.8 2

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(Table 1 continuedl Genus I species I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sam pie (Cerasus campanulatal CAFw 5040 3 3 2 2 2 109 27 60 370 6 0 5 0.5 2 Northeast 2 2 2 105 28 44 400 9 0 3 0.6 2 1 FHOw 8230 2 2 2 70 60 52 360 7 0 5 0.5 2 0 cerasoides FRIG 1208 2 3 3 2 3 85 38 50 370 7 0 6 ~8 2 Yunnan 3 3 3 2 3 86 28 64 390 6 0 8 ~7 2 clarofolia HEFw 126 1 2 2 2 3 94 27 45 380 8 0 5 0.3 2 Yunnan 3 3 3 2 2 88 18 65 400 6 0 7 1.5 2 1 HEFw 129 1 2 2 2 2 162 25 37 340 9 0 5 0.4 2 1 conradinae 3 3 2 2 3 56 11 65 400 6 0 6 0.5 2 0 dielsiana CAFw 17429 2 2 2 2 3 125 32 42 500 12 o 4 0.6 2 HEFw 3884 2 2 2 2 2 185 22 42 350 8 o 6 0.6 2 fruticosa 3 2 2 o mahaleb 3 2 2 150 40 45 o 5 0.7 2 maximowiczii Jining 2 2 33 290 o 3 0.4 2 1 FHOw 2166 2 3 176 37 45 300 7 0 3 0.6 2 0 prostrata diam. 8 mm 2 3 240 o 4 0.4 o diam. 6 mm 1 2 2 250 o 3 0.3 o Israel 2 2 2 230 o 3 0.6 o pseudocerasus HEFw 550 2 2 2 2 2 85 36 45 o 5 0.5 2 Guizhou 2 3 3 2 2 136 26 53 480 9 0 5 0.6 2 HEFw 130 2 2 2 2 119 43 38 300 8 0 6 0.5 2 serrula CAFw 46 2 3 2 2 3 58 43 55 360 7 0 5 0.5 2 Anhui 2 3 2 2 2 32 320 o 5 0.8 2 serrula/a HEFw 3160 2 3 3 2 3 192 45 36 270 8 0 7 0.6 2 FHOw 2083 3 2 3 72 50 57 360 6 0 5 0.5 2 0 CAFw 4865 2 3 2 2 93 34 47 410 9 5 0.5 2 0 serrulata var. sachalinensis 2 3 2 3 103 20 50 390 8 0 4 0.4 2 setulosa HEFw 133 2 2 2 3 117 19 47 460 10 o 4 0.4 2 CAFw 564 1 1 2 2 3 53 54 40 370 9 o 4 0.4 2 1 IOmenlosa 2 3 2 2 2 20 o 3 0.5 2 o vulgaris FHOw2793 3 2 3 154 40 42 o 4 0.4 2 o FHOw2798 3 2 3 176 22 45 o 5 0.4 2 1 England 3 2 3 72 36 46 360 8 o 5 0.5 2 o Switzerland 1 3 2 3 o yedoensis 2 2 2 3 50 360 o 4 0.4 Cercocarpus betuloides CAFw 2907 2 1 2 115 90 34 680 19 1 2 0.2 3 o FHOw 11328 2 2 2 75 91 39 o 3 0.2 3 1 Tw45872 2 2 82 98 40 340 8 o 3 0.2 3 o intricatus 2 1 183 290 o ledifolius 2 2 65 91 40 260 6 1 3 0.3 3 o Chaenomeles japonica 2 2 2 3 160 80 30 350 12 0 2 0.3 2

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(Table 1 continued) Genus / species/ 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sampie (Chaenomeles) sinensis 2 2 2 3 149 85 22 430 20 0 I 2 0.2 2 0 speciosa 2 2 1 2 3 264 93 23 350 16 I I 2 0.2 2 thibetica 2 3 2 2 3 36 97 63 550 9 0 o 3 0.4 2 Chamaebatia australia 2 2 2 328 82 25 270 11 0 0 3 0.2 0 C hamaebatiaria millefo li um 2 2 2 525 71 26 210 8 0 0 2 0.3 3 0 Coleogyne ramosissimum RSAw 8134 2 2 2 288 80 25 130 5 0 0 2 1.0 Califomia 2 2 2 130 o Cotoneaster granatensis 2 2 2 345 74 23 280 12 o I 3 0.2 2 o integerrimus 2 3 420 83 25 o o 2 0.2 2 o microphyllus CAFw 19327 2 3 2 2 3 315 69 24 300 12 o 4 0.2 2 o FHOw 12692 2 2 3 368 60 30 o I 2 0.3 2 o multiflorus 2 3 2 2 2 220 86 25 420 17 o I 2 0.2 2 1 nebrodensis 2 3 72 26 o o 2 0.2 2 o nummularia Israel 2 2 350 82 20 470 23 0 3 0.2 2 I Cyprus 2 2 2 2 650 60 20 280 14 0 2 0.2 2 0 Cowania stansburiana 2 82 210 o 0 3 0.2 2 0 Crataegus aronia 2 2 2 2 3 215 83 38 380 10 0 0 4 0.2 3 I aurantia 1 2 I 2 3 304 71 27 390 14 0 I 2 0.2 3 0 azarolus 2 2 3 2 3 250 74 35 440 14 0 1 4 0.2 3 I calycina 2 2 1 2 3 250 85 40 0 0 3 0.2 3 0 cuneata 2 2 2 2 3 197 74 32 370 12 0 1 3 0.3 3 douglasii 2 2 3 192 92 40 385 10 0 2 0.2 3 hupehensis Anhui 2 2 2 2 3 211 80 28 410 15 1 1 3 0.2 3 CAFw 239 2 2 2 2 3 128 70 37 280 8 0 0 3 0.2 3 I laciniata 2 2 I 2 3 300 8040300900 3 0.2 3 0 maximowiczii I I 2 3 65 350 2 0.2 3 0 monogyna Gesau I 2 2 3 288 95 32 320 10 0 2 0.3 3 I FHOw2769 I 2 3 176 76 32 350 11 0 3 0.2 3 0 Israel 2 2 2 2 3 325 86 26 320 12 0 4 0.4 3 I 4371 I 2 2 3 136 84 40 0 4 0.3 3 0 oresbia 2 3 2 2 3 456 44 27 600 22 0 2 0.2 3 oxyacantha Schaffhausen 1 2 3 208 77 36 320 9 o o 3 0.3 3 1 FHOw 2814 2 2 3 176 77 42 340 8 o I 4 0.3 3 0 pinnatifida 1 I 2 2 3 268 60 35 380 11 I o 3 0.2 3 0 pycnoloba 2 2 1 2 3 384 83 30 410 14 o o 3 0.2 3 shensiensis 2 2 2 3 222 76 29 420 15 1 4 0.3 3 sinaica 1 I 2 3 215 84 34 580 17 o 4 0.3 3 I wauina 2 2 2 3 140 83 33 310 9 o 4 0.2 3 0 wilsonii 2 2 2 3 184 76 31 390 13 o 4 0.3 3 Cydonia oblonga CAFw 5653 2 2 2 3 134 95 26 760 29 o I 2 0.2 3 1 FHOw 5100 2 2 3 368 60 30 480 16 o o 2 0.2 3 I Israel 2 3 2 3 150 90 38 440 12 o 3 0.3 3 0

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(Table 1 continued) Genus/ species/ 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sampie Dichotomanthes tristaniaecarpa 3 3 2 3 187 80 40 560 14 0 4 0.3 2 Docynia indica CAFw 6570 2 2 3 3 90 87 39 270 7 0 3 0.3 3 FHOw6570 3 3 116 93 38 430 11 0 3 0.3 3 Dryas octopetala diam. 25 mm 63 150 0 3 0.6 0 diam. 8 mm 74 60 0 2 0.5 0 Eriobotrya cavaleriei CAFw 14 1 2 3 49 96 48 930 19 1 2 0.3 2 Guangxi 2 2 3 3 48 98 57 910 16 0 2 0.4 2 deflexa 3 2 3 3 160 73 38 770 20 1 3 0.3 2 fragrans 3 3 2 3 142 92 31 740 24 2 0.3 2 japonica CAFw 7627 3 3 3 3 182 90 31 580 19 0 2 0.3 2 Guangxi 3 2 3 3 171 96 30 640 21 1 2 0.3 2 CAFw 19781 2 2 3 3 256 93 25 490 20 0 2 0.2 2 FRIG 1060 3 3 3 3 256 90 26 640 25 0 2 0.2 2 HEFw293 2 2 3 3 178 89 23 480 22 0 3 0.2 2 HEFw294 2 2 3 3 141 85 28 570 20 0 3 0.3 2 Eriolobus Irilobatus 2 2 2 2 2 110 78 35 640 18 0 3 0.3 2 E:wchorda giraldii 2 2 83 370 0 5 0.4 2 Fallugia paradoxa Tw 32069 2 2 80 170 0 0 3 0.3 0 CaIifomia 2 2 210 0 1 Hagenia abyssinica Tw 19975 3 3 3 3 11 45 115 650 6 0 0 9 1.0 3 0 FHOw9528 3 3 3 22 25 140 0 0 8 0.7 3 0 Hesperomeles helrophylla 3 3 88 76 40 450 11 0 0 2 0.2 4 0 lanuginosa 3 3 60 95 52 430 8 0 0 3 0.2 4 0 Heleromeles arbulifolia Tw45854 2 2 3 122 91 32 440 14 0 0 2 0.2 2 0 FHOw 11058 2 3 120 84 42 1 0 3 0.2 3 FHOw 11234 2 3 192 75 40 0 2 0.3 2 RSAw 6142 2 2 3 193 470 0 Holodiscus discolor Tw45970 1 2 2 3 53 78 60 310 5 0 0 6 3.3 0 CaIifomia 2 2 2 3 65 85 35 320 9 0 0 5 1.2 0 microphyllus 2 2 66 240 0 0 Kageneckia lanceolala 3 3 3 164 70 40 0 3 0.8 2 Kerria japonica diam. 10 mm 2 2 2 3 138 75 35 440 13 0 0 7 25.0 diam.12 mm 2 2 2 3 136 61 31 380 12 I 0 7 7.4

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(Table 1 cOIItinued) Genus! species! 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sam pie Laurocerasus fordiQIUJ 3 1 2 3 62 15 62 450 7 o 4 0.5 2 1 hypotriclUJ 2 3 2 3 53 24 75 360 5 o 5 0.8 2 o lusitanica Schweingruber 2 2 3 89 25 30 o 5 0.5 2 o FHOw 3127 3 60 5 43 o 5 0.7 2 1 KEWws.n. 3 173 16 40 470 12 o 5 0.7 2 o Iyonii 3 3 92 7 45 o 7 0.4 2 o officinalis FHOw9540 3 3 110 15 42 400 10 o 3 0.9 2 1 SwitzerIand 2 3 3 3 130 30 40 320 8 o 8 0.6 2 o phaeosticta CAFw 16995 2 1 2 3 116 21 36 410 11 o 4 Q3 2 o FRIGw460 2 3 2 3 73 21 60 410 7 o 3 M 2 o Guizhou 2 3 2 3 154 26 42 410 \0 o 4 Q3 2 o spinulosa FRIGw 1138 2 3 3 3 95 24 49 570 12 o 3 0.6 2 o CAFw 7621 3 3 3 3 111 41 50 500 10 o 3 0.4 2 o CAFw 15847 2 2 3 3 \07 36 48 230 5 o 4 0.5 2 o CAFw 12662 2 2 3 3 130 25 42 450 11 o 3 0.3 2 o Guangdong 2 3 3 3 199 23 47 470 \0 o 4 0.5 2 o Guangxi 2 3 3 3 136 35 42 430 \0 o 4 0.3 2 o CAFw 19173 2 2 3 3 125 21 40 670 17 o 4 0.3 2 o CAFw 4866 1 2 3 3 165 16 46 510 11 o 4 0.5 2 o CAFw 367 2 2 3 3 155 40 55 520 9 o 4 0.5 2 o FHOw 2105 3 3 176 32 50 450 9 o 4 0.5 2 o undulata CAFw 18043 2 3 2 3 27 24 60 620 10 0 4 0.8 2 CAFw 3406 2 2 2 3 37 16 68 400 6 0 12 0.9 2 zippeliana CAFw 16680 3 3 3 3 41 5 79 490 6 0 6 0.7 2 0 CAFw 9705 2 3 3 3 47 24 61 460 8 0 4 0.7 2 0 Lindleya mespelioides 3 2 2 83 430 o 3 0.3 Lyonothamnus floribu!!dus Tw48291 2 3 3 3 115 78 38 350 9 o 3 0.3 2 o FHOw 11239 2 3 3 62 89 40 o 4 0.3 2 Califomia 2 3 3 122 450 o Malus baccata Jining 1 I 2 3 76 450 o 3 Q3 0 CAFw 18070 I 3 2 3 218 28 45 570 13 o 2 Q2 3 0 CAFw 14225 2 3 2 3 165 58 44 480 11 o 2 0.2 3 0 baccata var. nigrecens 1 2 3 2 3 235 61 39 510 13 o o 3 Q2 3 o domestica I I 3 2 3 150 82 35 o o 3 Q2 3 o halliana 2 2 2 2 3 85 540 o o 2 Q2 o honanensis 2 2 2 3 168 74 35 420 12 o 3 Q2 3 hupehensis Anhui 2 3 I 2 3 51 420 o 1 2 0.2 o HEFw 123 2 2 2 3 150 70 43 460 11 1 o 3 0.2 3 manshurica 2 3 2 3 270 51 32 410 13 o o 2 0.2 3 melliana CAFw 15682 2 3 2 2 3 151 89 40 650 16 o 1 2 0.3 3 FRIGw 1814 2 3 2 2 3 208 60 34 650 19 o o 3 0.2 3

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(Table 1 continued) Genus! species! 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sampie (Malus melliana) HEFw 1377 2 2 2 2 3 183 80 32 610 19 3 0.3 3 pumila CAFw 13818 3 2 3 167 81 35 440 13 o o 3 0.2 3 o HEFw 1718 1 3 2 3 204 82 32 540 17 o o 3 0.3 3 o HEFw 3570 1 3 2 3 155 88 32 430 13 I o 3 0.2 3 o CAFw 5652 2 3 2 3 158 73 39 450 Jl o o 3 0.2 3 o rivularis 3 2 3 162 60 38 450 Jl 1 o 3 0.2 3 I rockii 3 3 2 3 73 84 42 500 12 o o 3 0.2 3 o siberica 1 1 1 2 3 293 73 29 440 15 o 2 0.2 3 o spectabilis 2 3 2 2 3 70 500 o 2 0.3 3 sylvestris SFCw 87 2 1 3 2 3 192 72 35 360 10 o I 2 0.3 3 o 4380 1 1 2 3 178 94 42 640 15 o o 2 0.3 3 o toringoides 2 3 2 2 3 256 73 35 430 12 1 o 3 0.2 3 1 yunnanensis 2 3 3 2 3 336 50 29 o 3 0.3 3 o Mespilus germanica Tw40867 2 3 2 3 256 86 32 410 14 0 3 0.3 3 0 FHOw 5719 3 2 3 272 74 35 0 2 0.3 3 0 Micromeles alnifolia HEFw 138 2 2 2 2 175 66 33 590 18 3 ~ 3 1 HEFw 1360 2 3 2 3 242 71 37 600 16 2 ~3 3 o CAFw 13729 1 1 3 2 3 209 54 44 770 18 2 ~ 3 o CAFw 5588 2 3 2 2 3 324 54 31 670 22 1 2 ~2 3 I CAFw 5315 3 2 3 320 58 36 600 17 1 2 ~ 3 o FHOw4548 3 2 3 224 63 46 420 9 o 3 ~3 3 o alnifolia var. lobulata 1 2 3 2 3 227 67 36 340 10 o 2 0.2 3 o caloneura 2 2 3 2 2 208 67 33 640 19 3 0.3 3 o dunnii 2 2 3 2 3 109 79 45 760 17 3 0.3 3 folgneri HEFw 2657 2 2 3 2 3 139 84 40 760 19 o 3 0.2 3 1 Yunnan 3 3 3 2 3 245 59 35 770 22 o 3 0.2 3 o CAFw 10963 2 2 3 2 3 113 73 47 730 15 o 3 0.3 3 o Guangxi 2 3 3 2 2 142 74 43 810 19 3 0.2 3 o hemsleyi HEFw 874 2 2 3 2 3 106 98 39 610 16 I 3 0.2 3 Yunnan 3 3 3 2 3 209 68 35 600 17 o 3 0.2 3 FRIGw 1249 3 3 3 2 3 140 78 35 700 20 o 3 0.3 3 Osmaronia cerasiformis Tw 32037 2 2 2 3 188 60 30 270 9 0 4 0.9 2 0 Tw 46422 2 2 3 72 82 41 350 9 0 5 0.5 3 0 Osteomeles anthyllidifolia 3 3 3 192 92 32 320 10 o 2 0.2 3 Padus brachypoda 3 3 2 2 90 24 48 380 8 o 8 0.5 3 buergeriana HEFw 135 1 2 2 2 3 170 54 38 380 10 o 8 0.5 3 I HEFw 3125 2 3 2 2 3 95 35 50 390 8 o 6 0.5 3 o grayana Sichuan 2 2 2 2 3 75 37 60 570 10 o 8 0.5 3 I CAFw 17647 2 3 2 2 3 143 21 65 450 7 o 12 0.5 3 o FHOw2136 2 2 3 130 18 52 400 8 o 4 0.4 3 o

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(Table 1 continued) Genus/ species/ 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sampie

(P adus grayana) CAFw 4101 2 2 2 3 143 44 49 370 7 0 8 0.8 3 0 CAFw4200 2 2 2 3 130 50 50 450 9 0 5 0.5 3 0 maackii Jining 1 2 3 21 300 0 3 0.5 3 0 CAFw 17308 2 2 3 112 40 53 550 10 0 2 004 3 0 FHOw2167 2 2 3 130 18 46 400 9 0 3 004 3 0 obtusata HEFw 1182 1 2 3 2 2 63 48 69 490 7 0 5 0.6 3 o HEFw 1434 2 3 3 2 2 110 32 50 490 10 0 7 004 3 o HEFw 814 2 3 3 2 2 40 47 63 440 7 0 8 0.3 3 CAFw 812 2 3 3 2 3 52 47 59 460 8 0 6 0.3 3 CAFw43 2 2 3 2 3 99 I3 45 380 8 0 8 004 3 perulara 2 2 3 2 3 79 10 55 390 7 0 10 1.0 3 racemosa CAFw 17309 3 2 3 140 32 45 260 6 0 4 0.2 3 0 Northeast 2 2 3 139 36 42 310 8 0 5 ~2 3 0 FHOw2165 2 3 48 68 60 380 6 0 5 ~3 3 0 Switzerland 3 3 2 3 220 24 40 400 10 0 5 004 3 0 racemosa var. pubescens 323250383028090 4 0.3 3 0 serotina FHOw 129 2 2 3 90 46 53 420 8 0 5 0.5 3 0 FHOw 130 2 2 3 98 43 55 430 8 0 5 0.5 3 0 ssioro 2 2 2 3 93 44 48 530 11 0 5 004 3 0 virginiana CAFw 18461 1 2 3 2 3 92 18 55 350 6 o 6 0.8 3 o FHOw 19481 1 3 2 3 99 37 55 380 7 o 5 0.7 3 o FHOw 11087 1 2 2 3 145 28 37 390 10 o 6 0.5 3 o wilsonii 2 3 3 2 3 48 5 75 520 7 o 7 0.9 3 o Peraphyllum ramosissimum 2 2 2 460 65 20 290 15 0 0 3 Petrophytum caespitosum 2 3 134 95 20 130 7 0 0 15 0.6 Photinia beauverdiana 2 2 2 2 3 120 90 44 600 14 1 5 0.3 2 benthamiana 2 3 2 2 3 104 72 47 750 14 o 5 004 3 davidsoniae Anhui 2 2 2 3 186 95 29 560 19 1 2 0.3 2 FRIGw 1179 2 3 3 3 155 86 31 660 21 o 2 0.2 2 Hainan 2674 3 3 3 3 180 82 37 660 18 o 3 0.2 2 glabra HEFw 596 2 2 3 3 200 97 24 480 18 o 2 ~5 2 1 Guangzhou 2 3 3 3 167 80 36 620 17 2 ~2 2 o HEFw267 2 2 3 3 257 92 25 510 20 I 2 ~ 2 CAFw 13053 2 3 3 1 3 112 93 31 640 20 o 2 ~3 2 prunifolia 2 3 3 1 3 161 93 30 620 20 o 2 ~2 2 schneideriana 3 3 2 2 3 100 94 45 670 15 o 5 004 3 se"ulata HEFw2000 2 3 2 3 259 90 24 470 20 1 3 0.2 2 FRIGw 1843 2 3 2 3 165 94 29 490 17 o 3 0.2 2 CAFw241 2 2 2 3 176 90 27 450 17 o 2 0.2 2 241 2 2 2 3 176 90 27 450 17 o 2 0.2 2 villosa CAFw 7009 2 2 2 2 3 145 85 40 650 16 5 004

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(Tab1e 1 continued) Genus / speciesl 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sampie (Photinia villosa) FHOw 11295 2 2 2 3 105 80 45 610 13 5 0.4 Physocarpus alternans 2 2 3 404 250 0 0 capitatus Tw45953 1 3 2 3 148 45 41 330 8 0 0 2 0.3 0 RSAw 144 2 2 3 184 80 35 250 7 0 0 3 0.4 0 Polylepis australia 3 2 3 159 77 25 0 3 0.2 3 0 incana 3 3 98 53 60 350 6 0 2 0.2 3 0 pal/idistigma 3 2 3 93 64 45 3 0.3 3 0 Potentilla caulescens 2 3 0 0 0 fruticosa Tw42599 1 2 85 210 0 0 0.3 0 Switzerland 2 2 80 0 0 0.4 0 Prinsepia sinensis 1 1 2 2 313 68 25 370 15 0 2 0.2 2 0 utilis 2 3 2 2 148 87 30 350 12 0 4 0.5 2 Prunus s. sir. cerasifera 2 2 2 288 9 33 290 9 0 4 0.5 2 0 domestica FHOw3079 1 3 2 3 150 45 38 0 1 6 0.5 2 0 Switzerland 1 2 3 2 3 0 0 2 0 insititia 1 2 2 3 166 43 38 290 7 0 5 0.5 2 0 pissardii 1 2 2 3 120 43 36 0 6 0.5 2 0 ramburii 2 2 3 170 50 38 280 7 0 5 0.7 2 0 salicina HEFw 132 1 2 2 2 2 180 20 47 360 8 0 5 0.5 2 0 Anhui 2 2 2 3 53 30 300 10 0 7 0.3 0 HEFw 3121 2 3 3 2 3 154 47 36 270 8 0 5 0.4 2 0 Guizhou 2 2 3 2 3 163 39 39 280 7 0 9 0.6 2 0 CAFw 15874 2 3 3 2 3 55 67 35 550 16 0 9 0.5 2 0 FRIGw 1241 2 3 3 2 3 110 56 38 310 8 0 8 0.5 2 0 spinosa FHOw2822 2 3 115 49 38 0 5 0.7 2 0 FHOw 1971 1 2 3 208 40 36 290 8 0 6 0.6 2 0 France 1 2 3 145 43 34 340 10 0 6 0.7 2 0 ursina 2 2 3 155 41 35 280 8 0 6 0.8 2 0 ussuriensis 2 2 2 150 25 36 250 7 0 6 0.5 2 Purshia glandulosa Tw48467 2 2 86 150 0 0 2 0.2 3 0 Califomia 2 2 180 0 0 tridentata 2 2 95 200 0 0 3 0.1 3 0 Pygeum africanum FHOw 39 3 3 3 19 5 135 440 3 0 5 0.5 2 0 FHOw2465 3 ~ 3 25 4 125 500 4 0 5 0.6 2 0 FHOw2060 3 3 3 30 14 105 450 4 0 5 0.7 2 0 21598 3 3 3 3 23 6 105 480 4 0 1 5 0.7 2 1 annularis 3 1 3 3 14 46 100 380 4 0 1 6 0.6 2 1 arboreum 3 3 3 3 10 56 175 710 4 0 0 4 0.4 2 0 griseum 3 3 3 3 12 28 125 550 4 0 0 6 0.7 2 0 javanicum 3 3 3 3 9 26 125 580 5 0 0 4 0.5 2 0

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(Table 1 continued) Genus I species I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sampie (Pygeum) latiJolium 3 3 3 3 13 20 115 530 5 0 I 4 0.4 2 0 martabanicum 3 1 3 3 17 30 125 420 3 0 0 5 0.5 2 0 parviflorum 3 3 3 3 15 45 130 o 0 5 0.5 2 0 polystachyum CAFw 6719 3 3 3 3 5 66 175 570 3 0 0 5 0.6 2 0 CAFw 2245 3 3 3 3 6 33 175 450 3 0 0 4 0.6 2 0 pullei 3 3 3 3 17 35 75 400 5 0 0 4 0.4 2 0 schlechteri 3 3 3 3 10 27 160 710 4 0 0 5 0.5 2 0 spec. 3 2 3 3 20 13 115 460 4 0 0 5 0.6 2 0 topengii FRIGw 22 3 2 3 3 11 34 125 530 4 o 5 0.5 2 o CAFw 14370 3 1 3 3 8 55 100 530 5 o 5 0.5 2 o CAFw 6571 3 3 3 3 8 20 110 530 5 o I 5 0.4 2 o vulgare 3 3 3 3 14 47 103 490 5 o o 5 0.4 2 o zeylanicum 3 3 3 15 43 150 580 4 o o 6 0.5 2 o Pyracantha coccinea 2 1 1 0 1 2 Jortuneana 2 3 2 3 224 88 32 290 9 0 3 0.3 2 Pyrus amygdaliformis 2 3 2 3 235 75 35 400 I I 0 0 2 0.2 4 0 aria CAFw 5001 2 2 3 192 56 35 410 12 0 3 Q3 3 I FHOw2475 2 2 3 192 56 35 410 12 0 2 Q2 3 0 aucuparia 2 2 3 224 32 44 450 10 I 3 0.3 4 0 betulaeJolia 2 2 3 2 3 340 67 27 480 18 0 3 0.2 3 0 calleryana HEFw 3710 2 2 3 2 3 170 65 35 530 15 0 3 0.3 4 0 HEFw 1661 2 3 3 2 3 298 53 29 590 20 3 0.2 4 0 communis FHOw4578 3 2 3 192 60 40 450 11 0 o 2 0.2 3 0 4357 2 2 3 176 88 36 0 1 2 0.2 4 0 Switzerland 2 3 2 3 160 93 23 250 10 0 o 2 0.2 4 0 malus FHOw2825 1 3 2 3 165 72 45 520 11 0 0 2 0.3 3 0 FHOw4581 1 3 2 3 128 94 42 400 10 0 0 3 0.3 3 0 FHOw2794 1 2 2 3 120 6240360 910 3 0.2 3 I Switzeriand 1 2 3 2 3 155 72 40 420 10 0 0 2 0.2 4 0 pashia 2 2 2 2 3 200 90 31 540 17 0 2 0.2 4 pyraster 3 2 3 o pyrifolia Anhui 2 3 2 2 3 278 55 31 460 15 0 3 0.2 3 0 Yunnan 2 3 3 2 3 128 71 47 360 8 0 3 0.2 3 0 pyriJolia var. (culta) 2 3 3 2 3 167 81 37 430 12 0 3 0.2 4 serrulata HEFw 329 2 2 3 2 3 210 59 38 590 16 1 3 0.2 4 1 FRIGw 1793 2 3 3 2 3 142 75 41 1 2 0.2 3 o HEFw785 2 3 3 2 3 169 79 33 530 16 o 3 0.2 4 sinensis FHOw2089 3 2 3 178 63 40 550 13 0 I 2 0.2 3 I FHOw2090 3 2 3 208 43 43 560 13 0 I 3 Q3 3 0 syriaca 2 2 3 2 3 230 78 33 470 14 0 o 3 Q2 3 ussuriensis CAFw 5928 2 2 2 2 2 333 34 26 560 21 0 4 0.2 3

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(Table 1 continued) Genus/ species/ 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sampie (Pyrus ussuriensis) Northeast 3 2 3 195 76 34 0 3 0.2 4 0 CAFw 18077 3 2 3 288 68 34 560 16 1 2 0.2 4 0 xerophila 3 2 3 188 85 35 500 14 0 3 0.3 4 0 Quillaja brasiliensis 3 3 2 2 40 95 62 290 5 0 5 0.2 3 0 Raphiolepis ferruginea HEFw 3861 2 3 2 3 118 90 32 860 27 0 2 0.4 2 0 FRIGw 1302 2 3 2 3 238 71 34 770 20 0 2 0.3 2 0 indica Anhui 2 3 2 3 319 91 16 510 32 0 2 0.3 2 0 Hainan 3 2 2 3 143 87 40 760 19 I 2 0.4 2 I Guangdong 3 2 2 3 197 86 29 370 13 0 2 0.2 2 0 FRIGw 1150 3 3 2 3 176 90 34 670 20 1 2 0.3 2 lanceolata 2 3 2 3 200 98 30 640 21 0 2 0.2 2 salicifolia 3 3 2 3 187 84 34 790 23 2 0.3 2 Rosa arabica 2 2 75 390 0 1 6 1.5 2 arvensis 2 75 320 0 10 2.2 I 0 canina FHOw2813 2 90 380 0 12 1.5 2 0 Israel 1 2 2 78 400 0 6 5.0 I 4390 1 2 2 90 0 8 8.5 0 cymosa 2 2 2 63 360 0 15 14.3 1 glauca 1 2 2 0 glutinosa 1 1 2 80 280 0 6 1.1 henryi Anhui 2 2 2 64 390 0 16 5.0 laevigata Anhui 2 3 2 91 340 0 12 3.0 1 1 CAFw 19798 2 2 2 96 400 0 7 4.6 1 1 macrophylla I 3 2 40 310 0 16 1.5 2 0 multiflora 2 3 2 65 310 0 12 10.0 1 1 phoenicea 3 2 2 95 380 0 7 1.4 pulverulenta 2 2 1 85 400 0 7 1.1 1 1 roxburghii 2 2 2 1 88 360 0 5 5.9 1 1 sempervirens 2 2 2 2 62 0 1 16 5.5 2 1 serrata 2 3 2 1 84 280 0 I 11 2.9 0 woodsii 2 3 2 190 0 0 xanthina 2 92 310 0 5 1.0 0 Rubus biflorus 2 3 2 3 97 43 48 300 6 0 0 10 4.2 0 chamaemorus 1 3 2 2 2 8 250 9 0 0 2 0.7 0 chingii 2 3 2 2 90 50 55 420 8 1 0 9 9.4 0 corchorifolius 2 2 2 2 85 69 37 460 13 0 0 10 3.6 0 coreanus 2 3 2 3 102 71 49 440 9 0 0 10 10.0 0 fruticosus diam. 3 mm 2 2 3 72 85 42 300 8 0 0 12 17.0 0 diam.12 mm 2 2 3 150 70 32 370 12 0 0 5 4.5 0 CAFw 5012 3 2 3 85 38 60 310 5 0 0 15 3.5 0 idaeus 2 2 3 140 70 30 I 0 5 5.5 0 saxatilis 2 2 3 0 0 swinhoei I 2 2 2 128 56 36 670 19 0 0 9 15.0 0 trianthus 2 2 2 2 84 46 46 420 9 0 0 9 14.1

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(Tab1e 1 continued) Genus/ species/ 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sampie Sarcopoterium spinosum Israel 2 2 3 225 12 41 250 6 1 0 12 1.0 Groece 2 2 2 160 30 32 0 0 8 0.6 Cyprus 2 2 3 310 28 36 0 0 7 1.1 Sibbaldia procumbens 3 2 2 450 65 20 140 7 0 0 0 Sibiraea altaensis 2 2 2 0 0 laevigata Zürich 2 2 97 170 0 0 4 1.1 0 Innsbruck 2 89 180 0 0 4 1.2 0 Sorbaria arborea Vl!r. subtomentosa 2 3 2 2 32 77 73 410 6 0 0 5 0.8 3 0 kirilowii 2 3 60 85 47 370 8 0 0 9 0.4 3 0 sorbifolia 2 3 83 84 45 370 8 0 9 0.6 3 0 Sorbus amabilis 2 3 2 2 66 380 0 2 0.2 3 aria 4348 3 2 3 176 92 37 500 14 0 2 0.2 3 0 Gesau 2 2 3 150 90 32 0 2 0.2 3 0 aucuparia 4327 2 2 2 400 62 28 380 14 2 0.2 3 0 67 2 2 3 128 87 46 450 10 1 3 0.2 3 0 Switzerland 2 3 2 2 0 CAFw 4202 2 2 2 3 240 70 42 410 10 3 0.3 3 0 coronata HEFw 1187 2 3 3 2 3 161 64 46 610 12 3 0.2 3 0 CAFw 7601 2 3 3 2 3 171 80 34 550 16 1 2 0.2 3 1 chamaemespilus 3 2 2 150 80 35 0 2 0.2 3 0 discolor HEFw 139 1 2 3 2 3 216 74 32 470 15 0 3 0.3 3 0 CAFw 5400 1 3 2 2 233 57 29 420 15 1 3 0.2 3 I domestica 2 3 2 3 175 85 40 0 3 0.3 3 0 koehneana HEFw 141 I 2 2 2 2 263 62 30 420 14 2 0.2 3 I CAFw 509 I 1 2 2 2 232 77 30 430 14 2 0.2 3 0 microcarpa 2 2 3 2 3 183 89 32 590 18 4 0.3 3 oligodonta 2 3 2 2 3 64 640 2 0.2 3 pohuashanensis CAFw 5317 3 2 2 215 63 32 440 14 I 3 0.3 3 0 FHOw 11046 3 2 3 240 75 35 370 10 0 3 0.2 3 0 prattii Yunnan 3 2 2 3 208 90 28 430 15 1 2 0.2 3 0 CAFw 7622 3 2 1 2 3 199 63 36 610 17 0 2 0.2 3 0 CAFw 19321 2 3 2 2 2 330 68 24 590 25 3 0.3 3 0 prattii var. tatsiensis 2 3 2 2 3 189 67 39 350 9 0 4 0.3 3 0 pteridophylla 3 3 1 2 3 175 70 38 550 15 2 0.2 3 I reducta 3 3 1 2 2 218 74 30 420 14 2 0.2 3 0 sargentiana 2 2 3 2 3 150 72 45 670 15 2 0.2 3 1 tianschanica 2 2 3 327 63 31 510 16 2 0.2 3 0

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(Table 1 continued) Genus I speciesl 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 sarnple (Sorbus) vilmorinii 1 2 2 3 127 80 32 580 18 1 2 0.1 3 0 wallichii 3 3 1 2 3 219 65 33 610 18 0 2 0.4 3 0 wilsoniana 2 3 3 2 2 207 63 33 600 18 3 0.2 3 0 Spiraea alpina 1 3 2 2 130 76 23 260 11 0 0 16 1.1 blumei 2 3 2 2 73 99 31 300 10 0 0 6 1.1 cantoniensis 2 2 2 2 90 99 19 290 15 0 0 7 2.0 chamaedryJolia 2 2 2 2 198 71 22 260 12 1 0 6 4.4 chinensis 2 2 2 2 62 91 43 1 0 7 2.6 hypericifolia 2 2 2 0 0 japonica var. Jortunei 2 3 2 2 135 82 21 350 17 0 0 7 2.7 pruniJolia 2 2 2 2 104 92 30 300 10 0 0 6 4.7 prunifolia var. simplicijlora 2 2 2 65 86 25 290 12 0 0 11 2.4 salicifolia Jining 2 2 385 78 24 290 12 1 0 6 1.7 0 FHOw 12694 2 2 240 70 30 270 9 0 0 7 1.0 0 Switzerland 2 2 480 80 24 260 10 0 7 1.5 0 thunbergii Anhui 2 3 2 2 43 97 29 390 13 0 0 7 4.2 0 Liaoning 1 2 2 136 69 24 260 10 0 0 6 3.3 tri/obata Anhui 2 2 2 2 53 98 28 280 10 0 0 6 1.7 1 CAFw 5470 2 2 2 128 95 25 320 13 0 0 6 2.5 0 Stephanandra chinensis diarn. 15 rnrn 2 2 2 3 109 67 40 630 16 0 0 6 2.6 diarn. 12 rnrn 2 3 2 3 125 77 31 540 17 0 0 6 4.1 Stranvaesia davidiana 2 2 2 3 419 77 22 520 24 0 2 0.3 2 Vauquelinia californica 2 2 3 2 200 74 32 430 14 0 4 0.2 2 0

Legend: 1 : Macroclirnate: 1 = ternperate; 2 =subtropics; 3 = tropics. 2: Moisture availability: 1 =dry; 2 = normal; 3 = mesic. 3: Habit: 1 =shrubs; 2 =intermediate between small trees and large shrubs; 3 =trees. 4: Phenology: 1 =evergreen species; 2 =deciduous species. 5: Ring-porosity: 1 =ring-porous; 2 =semi-ring-porous; 3 =diffuse-porous. 6: Vessel frequency (lsq.mm) [not given for ring-porous species]. 7: Percentage of solitary vessels (%). 8: Tangential vessel diameter (flJll) [not given for ring-porous species]. 9: Vessel element length (flJll). 10: LID ratio. 11: Multiple perforations: 0 =absent; 1 =occasionally present. 12: Helical vessel wall thickenings: 0 =absent; I = present. 13: Width of the widest rays (in cells). 14: Multiseriate ray height (mm). 15: Ray composition: 1 =rays composed of square (to weakly procumbent) cells and upright cells; 2 =hetero- geneous III to II (or I); 3 = homogeneous and heterogeneous III; 4 =homogeneous. 16: Crystals: 0 =absent; 1 =present.

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Statistical analyses Path coefficients can be presented in matrix notations as: Correlation analysis - The correlation co­ efficients between all (both non-wood ana­ ...... RlnJ (:,,] = (Ryl] tomical and wood anatomical) variables were ~ll calculated; the correlations between some R ...... R yn R ( nl nn yn wood anatomical characters and non-wood anatomical variables are also shown in fre­ quency distribution diagrams. ~~!A ~PYb Rab Path analysis - The correlation coefficient y. Pyb B provides a measure of association. However, correlation coefficients between variables (e. g., macroclimate, moisture availabiIity, ~ C habit and phenology) and wood anatomical Fig. 1. Path coefficient diagram. characters usually cannot be used to evaluate Figure 1 represents such a system of causal the importance of different variables in influ­ associations. Path coefficients are shown as encing various wood anatomical characters single arrows, correlations as double arrows. properly since these variables are not inde­ In this figure three factors, A, Band C, in­ pendent of one another. The same applies to fluence the dependent variable Y. Two of these the evaluation of mutual correlations among are correlated so that B influences Y not only different wood anatomical characters (Van directly (represented by direct path coefficient den Oever et al. 1981; Dickison & Phend Pyb) but also through the path B --.A --. Y 1985, Zhang & Zhong 1992). The partial re­ (represented by indirect path coefficient Rab. gression coefficient is one of the most impor­ Pya). Similarly, A exerts its influence clirectly tant indices to show the relation between a as weil as indirectly. Genererally, three path variable Xi and Y. However, partial regres­ coefficients can be estimated from a set (lf sion coefficients are expressed in the units three equations: of measurement of the respective parameters. Pya + Rab.Pyb + Rac.Pyc = Rya Therefore, expressed in these units the influ­ Pyb + Rab.Pya + Rbc.Pyc = Ryb ences of Xi are not directly comparable. Par­ Pyc + Rac.Pya + Rbc.Pyb = Ryc tial regression coefficients are directly compar­ The path diagram in Figure I defines Rac = Rbc = O. able only when they are expressed in units of The equation can thus be simplified into: standard deviation of the original measure­ Pya + Rab.Pyb = Rya ments, and are then called path coefficients. Pyb + Rab.Pya = Ryb Path analysis (cf. Pirchner 1969; Takeuchi Pyc = Ryc et al. 1982), as demonstrated by Zhang (1986) In situations in which causal factors (B and C and Zhang and Zhong (1992), is a useful tool for instance) are independent, the path coeffi­ to evaluate complex relations between wood cient (or Pyc) equals the simple correlation anatomical variables and physico-mechanical coefficient (or Ryc) between causal and depen­ properties. Path analysis is essentially based dent variables. This demonstrates further that on aseries of multiple regression analyses the correlation between two variables, Band with the additional assumption of causal rela­ Y for example, is equal to the sum of the con­ tions between the independent and dependent necting path, Ryb = Pyb + Rab.Pya. Here variables. The path coefficient equals the stan­ Rab.Pya is called the inclirect path coefficient dardised partial regression coefficient (Pyi): for the path from B --.A --. Y. Therefore, the Sxi correlation coefficient between Xi and Y in­ Pyi =Bi-- cludes the direct influence of Xi upon Y (or Sy direct path coefficient) as weil as indirect influ­ Where: Pyi = the path coefficient for the path ences of Xi through other variables (indirect from Xi to Y; Bi = the partial regression co­ path coefficients). With direct and indirect path efficient of Y on Xi; Sxi and Sy = standard de­ coefficients, therefore, the influence of a cau­ viations of Xi and Y respectively. sal factor Xi upon Y can be evaluated properly.

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Principal component analysis - The data phenology have been quantified as different set has also been subjected to principal com­ individual variables in the statistical analysis. ponent analysis (PCA). The main idea behind Ideally, systematic affinity should also be this analysis is that the first few principal com­ incorporated as a variable. Unfortunately, it ponents may weIl account for most of the is very difficult to meaningfully quantify sys­ variability in the original data. The aim of tematic affinity. Its possible influence, how­ principal component analysis, therefore, is to ever, will be considered individually. It is to search for the association between variables a certain extent correlated with habit: most and to summarise the co-variation among genera studied in the Spiraeoideae and Ros­ variables as accurately as possible using few oideae are shrubby or even herbaceous, components. The analysis is based on a cor­ while most genera studied in the Maloideae relation coefficient matrix of al1 variables. and Prunoideae are trees, or of intermediate The correlation matrix represents the com­ stature (viz. large shrubs to small trees) mon sources of variance among the variables. (Table I). Therefore, it may be expected that In component analysis, the original variables the correlations of habit with wood structure are transformed to a new set of variables are part1y the result of systematic alliance in which is not correlated with each other, and this family. arranged in order of decreasing variance. The transformation rotates the original axes (vari­ Results and Discussion ates) but maintains the original relationship Descriptive statistics for all sixteen param­ among data points. The new axes define in­ eters are shown in Table 2, and simple corre­ dependent patterns of variation (frequently lation coefficients between these parameters recognised as size- or shape-variables) that are given in Table 3. For each of the 12 wood should typify the sampIe. anatomical characters to be studied below, In the present study, ecology (viz. macro­ the frequency distribution diagrams (Figs. 8- climate and moisture availability), habit, and 27) will be presented first, followed by

Table 2. Descriptive statistics.

Variables Minimum Maximum Mean Standard deviation

Xl 1.00 3.00 1.77 0.68 X2 1.00 3.00 2.08 0.70 X3 1.00 3.00 2.02 0.82 X4 1.00 2.00 1.80 0.40 Y1 1.00 3.00 2.51 0.73 Y2 5.00 650.00 181.87 114.02 Y3 4.00 99.00 63.81 23.14 Y4 16.00 175.00 41.65 25.07 Y5 130.00 930.00 412.66 136.78 Y6 3.00 29.00 11.48 4.59 Y7 0.00 1.00 0.19 0.38 Y8 0.00 1.00 0.67 O.4fi Y9 1.00 16.00 4.57 2.77 Y10 0.10 25.00 0.97 2.01 Yll 1.00 4.00 2.25 0.80 Y12 0.00 1.00 0.45 0.47 Xl = macroclimate; X2 = moisture availability; X3 = habit; X4 = phenology; Yl = ring-por­ osity; Y2 = vessel frequency; Y3 = percentage of solitary vessels; Y4 = vessel diameter; Y5 = vessel element length; Y6 = LID ratio; Y7 = multiple perforations; Y8 = helical vessel wall thickenings; Y9 = ray width; YlO = ray height; Yll = ray composition; Y12 = crystals.

Downloaded from Brill.com10/07/2021 07:51:36AM via free access w Table 3. Correlation coefficient matrix between 16 parameters. I~

Xl X2 X3 X4 Yl Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 YI0 Yll Y12

Xl 1.0000* X2 0.4428 * 1. 0000* X3 0.1744* 0.1626* 1.0000* X4 -.5343* -.2305* -.1867* 1.0000* Yl 0.1774* 0.1545* 0.4613* -.1712* 1.0000* Y2 -.2841 * -.2472* -.2445* 0.2425* 1.0000* Y3 -.0384 -.0530 -.3394* 0.0309 -.0635 0.1864* 1.0000* Y4 0.4713* 0.2240* 0.3924* -.4254* -.5591* -.4370* 1.0000* Y5 0.3158* 0.3022* 0.4387* -.2689* 0.4844* -.2535* 0.0680 0.3169* 1.0000* Y6 -.0718 0.0385 -.0207 0.0480 0.3618* 0.4992* -.5295* 0.5253* 1.0000* Y7 -.0332 -.0155 -.0005 0.0376 0.1830* 0.1182 0.2226* -.1414* 0.3004* 0.3534* 1.0000*

Y8 -.0706 0.0529 0.2196* 0.0122 -.0525 0.0518 -.1728* -.2021* 0.1311* 0.2520* -.0220 1.0000* ...... Y9 -.0197 0.0644 -.2330* 0.1327* -.3816* -.3709* -.2436* 0.1573* -.2328* -.3945* -.2436* -.0590 1.0000* > :E YI0 -.0173 0.0690 -.3510* 0.1395* -.2733* -.1714* 0.0011 -.0054 -.0717 -.0939 -.0700 -.1903* 0.5779* 1.0000* > t:d Downloaded fromBrill.com10/07/2021 07:51:36AM Y11 0.0020 -.0177 0.4605* 0.0985 0.4777* 0.0810 0.0339 0.0333 0.3487* 0.1889* 0.2068* 0.2008* -.4612* -.4635* 1.0000* E- 0 Y12 0.1163 0.1036 0.0145 0.0384 -.0861 -.0555 0.1356* -.1945* 0.1252* 0.2487* 0.0811 0.2097* 0.0963 0.0631 -.1164* 1.0000* 5' ? I) * = Correlation coefficients are significant at 0.05 level (> 0.1189); the critical value for the significance at 0.01 level is 0.1557. ~ 2) Some of the results in this table are invalid since some wood anatomical characters (vessel diameter and ray width, for instance) do not show anormal distribution in the -< Rosaceae studied. ?- 3) Xl = macroclimate; X2 = moisture availability; X3 = habit; X4 = phenology; Yl = ring-porosity; Y2 = vessel frequency; Y3 = percentage of solitary vessels; Y4 = vessel w- diameter; Y5 = vessel element length; Y6 = LID ratio; Y7 = multiple perforations; Y8 = helical vessel wall thickenings; Y9 = ray width; YIO = ray height; YII = ray """'w composition; Yl2 = crystals. ~ ...... via freeaccess \Cl \Cl N Zhang, Baas & Zandee -- Wood structure of the Rosaceae 325

% sampies 100,,------, %'=p'" I 90 7°160 80 70 60 50j 50 III 40 :1 I L I 30 2°1 I L! 20 1O~ 10 0: . 01 I.. temperate subtroplCS tropics temperate subtropics tropics Fig. 2. Macroclimate and moisture availabil­ Fig. 4. Macroclimate and phenology (white = ity (white = mesic; black = normal; hatched = deciduous; black = evergreen). dry).

% sampies % sampies 70-'---- 601 i 50' I 40; ! 3°1 20~ 10~

temperate mesic normal dry

Fig. 3. Macroclimate and habit (white = trees; Fig. 5. Moisture availability and habit (white black = intermediate; hatched = shrubs). = trees; black = intermediate; hatched = shrubs).

path analysis results (Tables 4-13), in order percentage of the Rosaceae subjected to dry to test the validity of the ecological trend. conditions gradually increases from tropical, Mutual correlations among wood anatomical via subtropical to temperate regions (Fig. 2). characters (Tab1e 14) and their possib1e ef­ The percentage of trees increases from tem­ fects on eco10gical trends (Tab1e 15) are also perate, subtropical, to tropical regions, while examined. In addition, mutual corre1ations the percentage of shrubs decreases (Fig. 3). among wood anatornical characters are also The differences in habit between temperate explored by principal component analysis and subtropical regions are, however, very (Table 16, Fig. 28). Before dealing with the limited (Fig. 3). The percentage of evergreen relations of each wood anatomical characters species decreases from tropical, via subtropi­ to macroclimate, moisture availability, habit, ca!, to temperate regions, whi1e the percentage and phenology, the mutual correlations be­ of deciduous species increases (Fig. 4). With tween the four non-wood anatomical vari­ increasing moisture availability, the percent­ ables will be explored first. age of trees increases gradually, while the percentage of shrubs decreases (Fig. 5). With Relationships among macroclimate, moisture increasing drought, the percentage of decid­ availability, habit, and phenology uous species increases (Fig. 6). The percent­ Mutual relationships between these four age of deciduous species increases with de­ variables are pictured in Figures 2-7. The creasing plant size (Fig. 7). In summary, in

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%samples % sampies 90 80 70

60j 50 40 n 30 20 10 0 mesic normal dry mesic normal dry Fig. 6. Moisture availability and phenology Fig. 9. Moisture availability and ring-poros­ (white = deciduous; black = evergreen). ity (white = diffuse-porous; black = semi­ ring-porous; hatched = ring-porous).

% sampIes % sampIes 90r- 801 111 80 70i nI I ~.m1 n nI 60~ i i n I I i 501 i I , I I 404 I 1 40 I 1 I I I ' 30~ , I 30 20' 20 10~ 10 O-'-·_-L- 0+--' ---'---" trees intermediate shrubs shrubs intermediate trees

Fig. 7. Habit and pheno1ogy (white = decid­ Fig. 10. Habit and ring-porosity (white = dif­ uous; black = evergreen). fuse-porous; black = semi-ring-porous; hatch­ ed = ring-porous).

% sampies % sampIes 90, ; I 80 1 i I 80 70i I : 60 1 60 50 1 n' I n I 1 I 50 40 :1 11 I1 11 30 ~~j 111 IL I. temperate su btropics tropics deciduous evergreen

Fig. 8. Macroclimate and ring-porosity (white Fig. 11. Phenology and ring-porosity (white = diffuse-porous; black = semi-ring-porous; = diffuse-porous; black = semi-ring-porous; hatched = ring-porous). hatched = ring-porous).

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Table 4. Path analysis of ring-porosity (Yl).

Xl -tYI X2 -tYl X3 -tYl X4-tYl P-value Xl-t 0.0526 0.0216 0.0758 0.0274 0.4485 X2 -t 0.0233 0.0487 0.0707 0.0118 0.4213 X3 -t 0.0092 0.0079 0.4346* 0.0096 0.0000 X4 -t -.0281 -.0112 -.0811 -.0513 0.4250

Xl = macroclimate; X2 = moisture availability;X3 = habit; X4 = phenology. * Direct path coefficient significant if P-value < 0.05. tropical regions, Rosaceae species tend to oc­ deviation increase in habit (cf. Table 2). The cupy more mesic habitats, plant size is usu­ influence of the other three factors actually ally larger, and the species are more often is insignificant although Figures 8, 9 & 11 evergreen than in the temperate regions. Sub­ show elose relations between them and ring­ tropical provenances are usually intermediate. porosity, and their simple correlation coeffi­ cients are all significant (see Table 3). If the W ood anatomical characters in relation to correlation coefficients of these three vari­ ecology, habit and phenology, and their mu­ ables with ring-porosity (0.1774, 0.1545 and tual correlations -0.1712, respectively) are compared with their direct path coefficients (0.0526, 0.0487 Ring-porosity (Yl) and -0.0513, respectively, see Table 4), the Ring-porosity decreases from temperate, respective direct path coefficients are appar­ via subtropical, to tropical regions, while dif­ ently lower than their correlation coefficients, fuse-porosity increases (Fig. 8). Serni-ring­ but the indirect path coefficients of these vari­ porosity shows less change with macrocli­ ables through X3 (habit), or XI (X2 or mate. The Rosaceae are predominantly dif­ X4) -tX3 -tYl, are relatively high (0.0758, fuse-porous. With decreasing moisture avail­ 0.0707 and -0.0811, resp.). This means that ability, diffuse-porosity decreases, while ring­ correlations of these three variables with ring­ porosity increases. Serni-ring-porosity shows porosity include a large indireet influence little variation with moisture availability (Fig. through habit. In other words, the effects of 9). Diffuse-porosity increases appreciably these three variables on ring-porosity can be from shrubs, via intermediate-sized plants to largely explained by their relationships 10 trees, while both serni-ring-porosity and ring­ habit. Consequently, the importance of these porosity decrease (Fig. 10). Furthermore, variables in controlling ring-porosity is exag­ both trees and intermediate-sized plants are gerated if based on their simple correlation predominantly diffuse-porous, while ring­ coefficients. The correlation between habit porosity, serni-ring-porosity and diffuse-por­ and ring-porosity revealed by path analysis is osity are all common in shrubs. From decid­ hardly influenced by systematic affinity. Ring­ uous to evergreen species, diffuse-porosity porosity occurs fairly haphazardly throughout increases significantly, while both ring-por­ the family and does not characterise major osity and serni-ring-porosity show a decrease aIliances (Zhang 1992). (Fig. 11). As shown in Table 14, porosity (YI) is Path analysis (Table 4) reveals that the most closely correlated with vessel element direct path coefficients for the four variables length (Y5): ring-porous Rosaceae tend to to ring-porosity are 0.4346 (habit), 0.0526 have shorter vessel elements. In addition, the (macroclimate), -0.0513 (phenology) and percentage of solitary vessels, helical vessel 0.0487 (moisture availability) in declining wall thickenings, ray width and ray composi­ sequence. This means that the expected in­ tion are also significantly correlated with por­ crease in ring-porosity is 0.4346 standard osity. The associations of diffuse-porosity deviation units of ring-porosity per standard with longer vessel element and lower inci-

Downloaded from Brill.com10/07/2021 07:51:36AM via free access 328 IAWA Bulletin n.s., Vol. 13 (3),1992 dence of vessel wall thickenings in the Rosa­ ingless; only that in this family the correlation ceae fit the Baileyan model, but the other can be explained by the association of habit relations do not. It has been suggested that and phenology (Fig. 7, Table 3), and the over­ some ecological trends may be due to correla­ riding relation between habit and porosity. tive restraints among wood anatornical char­ acters (Baas 1986). In order to test the validi­ Vessel jrequency (Y2) ty of the ecological trends, not only four non­ Vessel frequency decreases from temper­ wood anatornical variables but wood anatorni­ ate, via subtropical to tropical regions (Fig. cal characters themselves are considered as 12). But, the difference in vessel frequency variables for each wood anatornical character between subtropical and temperate regions is studied. The standardised partial regression evidently smaller than the one between sub­ coefficients of each wood anatomical char­ tropical and tropical regions. With decreasing acter on the four non-wood anatomical vari­ moisture availability (viz., from mesic, via ables (the standardised partial regression co­ normal, to dry), vessel frequency increases efficients of each wood anatomical character gradually in this family (Table 3). With in­ on other wood anatomical ones are omitted) creasing plant size, vessel frequency de­ are shown in Table 15. Like earlier results creases appreciably. Meanwhile, the range (Table 4), both macroclimate and moisture of vessel frequency tends to decrease gradual­ availability still do not influence porosity ly. Trees have a narrower range of 5-350/ significantly. It means that the mutual corre­ sq.mm. Shrubs, however, range from 50 to lations of porosity with other wood anatorni­ cal characters do not significantly influence ecological trends revealed by path analysis. % sarnples In addition, the relations of both habit and phenology to porosity are not influenced sig­ 50n45 nificantly, either, although the direct path co­ 40 35 1 efficient from habit to porosity drops dramat­ 30 ically from 0.4346 (see Table 4) to 0.1425 25 (Table 15). 20 15 1 A comparison of the incidence of ring­ 10 porosity in the Rosaceae with data in the liter­ ature yields only few paralleis. The more o5 I IISIEIE}EIIII!,I'CJ[.~~ , 50 100 150200250300350400450500600 common incidence of ring-porosity in tem­ vessel frequency (lsq. rnrn) perate regions than in the tropics is weIl doc: urnented (e.g. Baas et al. 1983; Wheeler & Fig. 12. Macroclimate and vessel frequency Baas 1991), and this can only partly be due (white = temperate; black = subtropics; hatch­ to a general decrease in plant size with higher ed = tropics). latitudes, because some ring-porous temper­ ate species are large trees (e.g.oak, ash, elm). In the flora of the Middle East ring-por­ % sarnples osity increases from dwarf shrubs to large 30r--- trees (Baas et al. 1983), in strong contrast 25 1 with our findings for the Rosaceae. The gen­ 20j eral trend for ring-porosity to be associated 15 with deciduousness has numerous exceptions 1 (cf. Chowdhury 1964). Photinia is an exam­ 10 pIe where both deciduous and evergreen are 5 characterised by diffuse-porosity. The fact 01 1llllllllll1lhlLi. r. n 0 that path analysis does not show a significant 50 100 150 200 250 300350 400 450 500 600 vessel frequency (lsq.rnrn) effect of phenology on porosity in the Rosa­ ceae, does not imply that the simple correla­ Fig. 13. Habit and vessel frequency (white = tion (Fig. 11, Table 3) is biologically mean- shrubs; black = intermediate; hatched = trees).

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Table 5. Path analysis of vessel frequency (Y2).

X1-tY2 X2 -tY2 X3 -tY2 X4-tY2 P-value X1-t -.1381* -.0588 -.0313 -.0559 0.0496 X2 -t -.0612 -.1328* -.0051 -.0241 0.0380 X3 -t -.0241 -.0216 -.1793* -.0195 0.0023 X4 -t 0.0738 0.0306 0.0335 0.1046 0.1234

Xl = macroclimate; X2 = moisture avaiIabiIity; X3 =habit; X4 =phenology. * Direct path coefficient significant if P-value < 0.05.

600/sq.mm (Fig. 13). As shown in Table 3, ray width, which are most closely correlated deciduous species tend to have higher vessel with vessel frequency. The relations of vessel frequencies than evergreen ones. frequency with habit and phenology are, Table 5 indicates that plant habit is the however, not influenced significantIy by the most important factor influencing vessel fre­ mutual wood anatomical correlations. quency (-0.1793). In addition, both macro­ The ecological trends of vessel frequency climate (-0.1381) and moisture availability in this family conforrn to the generaiones (-0.1328) also show a significant effect on established in numerous phylads and regional this character. Phenology, however, does not floras (Baas 1973, 1986; Baas & Carlquist show a significant influence despite its signi­ 1985; Baas et al. 1983; Van den Oever et al. ficant correlation coefficient with vessel fre­ 1981; Carlquist 1977a; Carlquist & Hoekrnan quency (Table 3). The latter includes a compa­ 1985; Wheeler & Baas 1991). Both moisture ratively large indirect influence through ma­ availability and macroclimate show appreci­ croclimate (indirect path coefficient 0.0738, able effects on this character. But it should be see Table 5). kept in mind that habit also has a significant Vessel frequency is mainly correlated with influence. Systematic affinity cannot have LID ratio and vessel element length (Table influenced these results significantly since 14). Multiple regression analysis, however, vessel frequency is of poor systematic value does not reveal a significant correlation be­ in this family (Zhang & Baas 1992; Zhang tween vessel diameter and vessel frequency 1992). although this character has the highest simple correlation coefficient with vessel frequency Percentage 01 solitary vessels (Y3) (Table 3). Van den Oever et al. (1981) also Macroclirnate and moisture availability do found that vessel frequency is significantly not show a significant relation with the per­ correlated with vessel element length, but not centage of solitary vessels (Table 3). How­ with vessel diameter in Symplocos. A signi­ ever, vessel grouping increases gradually ficant and negative correlation of vessel fre­ with increasing plant size in the Rosaceae quency with vessel element length was noted (Fig. 14). High degrees of vessel grouping by Giraud (1980) in Entandrophragma. are somewhat less common in shrubs than As shown in Table 15, the standardised in trees. There is no relation between phe­ partial regression coefficients of vessel fre­ nology and the percentage of solitary vessels quency on both macroclimate and moisture (Table 3). availability drop to a very low value (0.0494 As shown in Table 6, only habit shows and -0.0678 respectively), both of which are a significant influence on the percentage of insignificant. It suggests that the significant solitary vessels (or vessel grouping). As ecological trends found for vessel frequency, pointed out earlier (Zhang & Baas 1992; to a large extent, may result from its mutual Zhang 1992), the percentage of solitary ves­ correlations with some other wood anatomi­ sels is of high systernatic value in this family. cal characters. These wood anatomical char­ The arborescent subfamily Prunoideae is acters mainly include vessel element size and generally characterised by a higher degree of

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% sampies % samPles~ ______i 45~ .--, 40~ ::1 35j ~ 40 n 301 I: 30j35 :i 'I 25 1 201 ;~l' 1 , ' 151 10' ;~~ il ~ ~ 5J 1 I ~ ~1 "ILi ~ ~ ~ ~ ~ ~ o 10 30 50 70 90 10 20 30 40 50 60 70 80 90 lOO llO 120 ISO solitary vessels (%) tangential vessel diameter {j.lm)

Fig. 14. Habit and percentage of solitary ves­ Fig. 16. Habit and vessel diameter (white = sels (white = shrubs; black = interrnediate; shrubs; black = intermediate; hatched = trees). hatched = trees).

% sampies % sampies 45--- 40 1 40j 351 I 351 30' 30j 251 25~ 20 20j 15 15 J 10] 10 5j 5 01 n:' iE!'EI~!_,!",~_~,_~ ~. rs ~ ~ 01 n IIIIIIIIII~~ • I I I 10 20 30 40 50 60 70 80 90 100 llO 120 150 tangential vessel diameter {j.rm) tangential vessel diameter (j.lffi)

Fig. 15. Macroclimate and vessel diameter Fig. 17. Phenology and vessel diameter (white (white = temperate; black = subtropics; hatch­ = deciduous; black = evergreen). ed = tropics). vessel grouping (the percentage of solitary Vessel diameter is not significantly correlated vessels smaller than 60%), while most gen­ with the percentage of solitary vessels despite era of the shrubby Spiraeoideae and Rosoi­ its high simple correlation coefficient with deae are characterised by an appreciably this character (Table 3). It is difficult to inter­ lower degree of vessel grouping (the percent- pret the elose relation between vessel group­ age of solitary vessels mostly larger than ing and LID ratio. However, the Baileyan 60%). Therefore, it is expected that the signi­ model considering solitary vessels and rela­ ficant and negative correlation between habit tively long and slender vessel elements to be and the percentage of solitary vessels reveal­ associated with the primitive wood syndrome ed by path analysis mainly results from sys­ fits the Rosaceae. Like in porosity, the mutual tematic differences. Path analysis did not correlations of vessel grouping with other reveal any significant correlations of vessel wood anatomical characters do not influence grouping with ecology (e.g. macroelimate its ecological trends significantly (Table 15), and moisture availability) and phenology. but phenology in this case (Table 5), shows a The percentage of solitary vessels increases significant (but very weak) correlation with significantly with increasing LID ratio (Table vessel grouping. 14). In addition, several other characters like Van der Graaff and Baas (1974) did not helical vessel wall thickenings, vessel ele­ find any effects of macroclimate on vessel ment length and vessel frequency also show grouping. An analysis of the European flora a significant correlation with this character. by Baas and Schweingruber (1987) did not

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Table 6. Path analysis of solitary vessels (Y3).

Xl~Y3 X2~Y3 X3~Y3 X4~Y3 P-value

X1~ 0.0090 -.0035 -.0602 0.0163 0.9039 X2 ~ 0.0040 -.0079 -.0562 0.0071 0.9029 X3 ~ 0.0016 -.0129 -.3454* 0.0057 0.0000 X4 ~ -.0048 0.0018 0.0645 -.0306 0.6561

Tab1e 7. Path analysis of vesse1 diameter (Y 4).

Xl ~Y4 X2~Y4 X3~Y4 X4~Y4 P-value

X1~ 0.3078* -.0050 0.0523 0.1163 0.0000 X2 ~ 0.1363 -.0112 0.0488 0.0502 0.8396 X3 ~ 0.0537 -.0182 0.3000* 0.0406 0.0000 X4 ~ -.1645 0.0026 -.0560 -.2176* 0.0003

Xl = macroclimate; X2 = moisture availability; X3 = habit; X4 = phenology. * Direct path coefficient significant if P-value < 0.05. reveal a correlation between vessel grouping decrease with decreasing moisture availabili­ and moisture availability. Instead, they no­ ty. The influence of moisture availability on ticed that the percentage of the species with vessel diameter, however, is smaller than almost exclusively solitary vessels (over that of macroclimate in this farnily, as shown c. 80% of all individual vessels) in cool tem­ in Table 3. Vessel diameter increases with perate to boreal elements is much higher than increasing plant size (Fig. 16). As shown in in the mediterrane an and warm subtropical Figure 17, evergreen species tend to have floras. In the flora of the Middle East (Baas wider vessels than deciduous ones. Again, et al. 1983), vessel grouping shows a slight this is mainly caused by evergreen Pygeum increase in arid habitats over the mediter­ with its large vessel diameters. ranean and more mesic habitats. Carlquist Path analysis (Table 7) shows that macro­ (1984a, 1988) noted that vessel grouping climate, habit, and phenology show a sig­ may increase with increasing drought in nificant effect on vessel diameter. Moisture some phylads, but that no vessel grouping availability, however, does not show a signi­ occurs even though habitats may be very dry ficant effect despite a significant correlation if imperforate tracheary elements with large coefficient (Table 3). This correlation actually bordered pits constitute the ground tissue. In includes an indirect effect through macrocli­ the Rosaceae, relatively high degrees of ves­ mate, the indirect path coefficient for the path seI grouping are also related to areduction in from X2~X1 ~Y4 is as high as 0.1363 size and number of bordered pits in the walls (Table 7). The same applies to phenology. of the imperforate tracheary elements (Zhang Although its correlation coefficient with ves­ 1992). seI diameter (-0.4252) is highest among the four variables, its influence on vessel diam­ Vessel diameter (Y4) eter (direct path coefficient -0.2176) is ac­ Tangential vessel diameter tends to in­ tually smaller than those of macroclimate crease from temperate, via subtropical to (0.3078) and habit (direct path coefficient tropical regions (Fig. 15). Vessel diameter 0.3000) since its correlation with vessel distribution in the tropics is bimodal due to diameter also includes a large indirect effect large vessel diameters in Pygeum. It tends to through macroclimate as weil as habit.

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% sampies Vessel diameter is mainly correlated with vessel element length and of course with 35 n 1 n 30 LID ratio (Table 14). It increases significant­ ly with increasing vessel element length. In 25 Symplocos (V an den Oever er al. 1981), ves­ 20 seI diameter was not significantly correlated 15 with either vessel element length or vessel 10 frequency. Giraud (1980), however, noted a 5 significant correlation of vessel diameter with 01 r§ 11 111 1E 111,1 11 rE,"" rw 100 200 300 400 500 600 700 800 900 vessel element length in Enrandrophragma. vessel element length üun) The mutual correlations of vessel diameter with other wood anatomical characters do not Fig. 18. Macroclimate and vessel element significantly influence its macroclimatic trend length (white = temperate; black = subtropics; as weIl as its relations with habit and phe­ hatched = tropics). nology although the standardised partial re­ gression coefficients of vessel diameter on macroclimate, habit and phenology all drop moderately (cf. Tables 7 & 15). The significant macroclimatic trend for vessel diameter in this family is similar to the % sampies general one found in many phylads (Baas 40, 1973; Baas & Zhang 1986; Baas et al. 1988; 35 30 Carlquist 1977a; VanderGraaff & Baas 1974; 25 Van den Oever et al. 1981; Wheeler & Baas 20 1991). Although a significant and positive 15 correlation between vessel diameter and habit 10 found in this family may include some sys­ 5 tematic differences, the positive correlation 0\ 1\ \-i\~i\_\_-\_~!W;i WN - between the two factors is probably of gen­ vessel element length (11m) eral validity. Significantly wider vessels in evergreen species than deciduous ones in this Fig. 19. Habit and vessel element length family as revealed by path analysis may be (white =shrubs; black =intennediate; hatch­ largely due to the overriding effects of the ed = trees). large number of evergreen Pygeum species (Fig. 17). Within the genus Photinia, the sit­ uation is reversed: the deciduous species have wider vessel elements than the evergreen species (Zhang & Baas 1992; Zhang 1992).

% sampies Vessel element length (Y5) 40.,--- Like vessel diameter, vessel element length 35 decreases significantly from tropical, via sub­ 30 25 tropical to temperate regions (Fig. 18). Vessel 20 element length also decreases with decreasing 15 moisture availability (Table 3) or decreasing 10 plant size (Fig. 19). Evergreen species have 5 longer vessel elements than deciduous ones 01 Cl 'l'III'I'I'lcI- (Fig. 20). All 4 variables, as shown in Table 100 200 300 400 500 600 700 800 900 vessel element length (Ilffi) 3, have a significant correlation coefficient with vessel element length. Fig. 20. Phenology and vessel element length Path analysis (Table 8), however, reveals (white =deciduous; black =evergreen). that vessel element length in this family is

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Table 8. Path analysis of vessel element length (Y5).

Xl~Y5 X2~Y5 X3~Y5 X4~Y5 P-value

Xl~ 0.1290 0.0722 0.0649 0.0496 0.0550 X2 ~ 0.0571 0.1631* 0.0605 0.0214 0.0056 X3 ~ 0.0225 0.0265 0.3723* 0.0173 0.0000 X4~ -.0689 -.0376 -.0695 -.0929 0.1354

Xl = macroclimate; X2 = moisture availability; X3 = habit; X4 = phenology. * Direct path coefficient significant if P-value < 0.05. mainly influenced by habit, and to a lesser is much lower (-0.0184). As revealed ear­ extent by moisture availability. The effects of lier, habit still shows a significant correlation the two factors are statistically significant. with vessel element length and phenology Macroclimate shows a statistically insignifi­ does not. cant effect on vessel element length (0.1290) Vessel element length variation with ecol­ although its simple correlation coefficient ogy in this family conforms to general trends (0.3158, see Table 3) with vessel element (Baas 1976, 1982, 1986; Carlquist & Hoek­ length is even higher than that of moisture man 1985; Carlquist 1988). It decreases ap­ availability (0.3022). Macroclimate (shown preciably either with decreasing moisture in Table 8), has a large indirect effect on ves­ availability, or from tropical, via subtropical seI element length through moisture availabil­ to temperate regions. The elose relations of ity and habit. Therefore, moisture availability vessel element length with latitude found in is more important in influencing vessel ele­ some phylads (Baas 1973; Dickison & Phend ment length than macroclimate, which is dif­ 1985; Van der Graaff & Baas 1974; Van den ferent from the case in vessel diameter. Phe­ Oever et al. 1981) may partly result from dif­ nology, however, shows little influence on ferences in moisture availability. Although a vessel element length. The trend that ever­ significant and positive correlation between green species have longer vessel elements as habit and vessel element length in the Rosa­ shown in Fig. 20 results from a elose relation ceae may inelude some systematic differ­ of phenology to habit and macroclimate, and ences, this positive trend seems to be univer­ its correlation coefficient with vessel element sal. A similar reduction of vessel element length, as shown in Table 8, ineludes a com­ length with decreasing plant size was also paratively large indirect effect through habit noted in the flora of southem Califomia and macroclimate. As was the case for vessel (Carlquist & Hoekman 1985); however, their diameter, the significant relation between herbs had Ion ger vessel elements than shrubs. habit and vessel element length as revealed A elose and positive correlation between by path analysis mayaiso inelude some sys­ habit and vessel element length occurs in all tematic differences (Zhang & Baas 1992). ecological categories of the Middle East Vessel diameter and (of course) LID ratio (Baas et al. 1983). are the two characters which are most signi­ ficantly correlated with vessel element length LID ratio (Y6) (Table 14). Manyothercharacters show weak, There are no significant relations between yet significant correlations with it as weil. As length/diameter (LID) ratio of vessel element shown in Table 15, the mutual correlations of and macroclimate, moisture availability, habit vessel element length with other wood ana­ or phenology (Table 3). Path analysis con­ tomical characters do not infIuence its relation firms this (data not shown). In other words, with moisture availability significantly, but the ratio is statistically independent of ecol­ the standardised partial regression coefficient ogy in this family. So far no other ecological of vessel element length on macroclimate, analysis of this ratio has, to our knowledge, compared with the earlier result (Table 8), been carried out.

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Table 9. Path analysis of helical vessel wall thickenings (Y8).

Xl ~Y8 X2~Y8 X3~Y8 X4~Y8 P-value

X1~ -.1498 0.0355 0.0404 0.0033 0.0503 X2 ~ -.0663 0.0802 0.0377 0.0014 0.2286 X3 ~ -.0261 0.0130 0.2316* 0.0011 0.0018 X4 ~ 0.0800 -.0185 -.0432 -.0061 0.9308

Xl = macroclimate; X2 = moisture availability; X3 = habit; X4 = phenology. * Direct path coefficient significant if P-value < 0.05.

Multiple perforations (Y7) significant correlation with the incidence of The Rosaceae are characterised by almost multiple perforations (Table 15). exclusively simple perforations (Zhang & Baas 1992; Zhang 1992). Multiple perfora­ Helical vessel wall thickenings (Y8) tions were found in very limited specimens Helical vessel wall thickenings are of com­ and are usually restricted to a very low pro­ mon occurrence in this family, but often vary portion of the vessel perforations if they occur. within genera or even species. They may be Therefore, one may doubt the value of analys­ well developed or restricted to narrow vessel ing any possible relations of the incidence of elements or to the tails only. No attempt was the multiple perforations to ecology, habit or made to quantify these differences for the phenology in this family. Actually, no con­ present statistical analysis; we onl y discrimi­ sistent relations of this character to the four nated between presence or absence of any variables were found (Table 3). Path analysis expression of helical vessel wall thickenings. also confirms that none of the four factors Their incidence in subtropical and temper­ shows a significant effect (data not shown) ate species is slightly higher than in tropical on the incidence of multiple perforations. In species, but this difference is not significant Myrtaceae Schmid and Baas (1984) found a (Table 3). Moisture availability has no sig­ weak tendency for species with mixed simple nificant influence on this character, either and scalariform perforations to favour cool (Table 3). Habit, however, has a significant mesic habitats. For woods with exclusively effect (Tab1e 3). Shrubs have a significantly or predominantly scalariform perforations lower incidence of helical vessel wall thick­ strong ecological trends were reported in enings than either intermediate-sized species several floristic surveys (Baas 1976, 1982, or trees (Fig. 21), but the difference between 1986; Carlquist 1988). A fossil wood survey trees and intermediate-sized species is re- (Wheeler & Baas 1991) also found distinct ecological trends in the incidence of scalari­ form perforations throughout fossil record from the Cretaceous to the modem flora. % sampies Multiple regression analysis (Table 14) re­ 90r'------r~------~ veals that incidence of multiple perforation is 80 only significantly and positively correlated 70 with vesse1 element length. Bailey and Tupper 60 50 (1918) already clearly showed that multiple 40 perforations are associated with longer vessel 30 I elements; but to our knowledge this is the 20i 1Q! first report where even the incidence of spo­ I radic multiple perforations is associated with O'-'--~­ shrubs trees longer vessel elements. When the mutual cor­ relations are considered, none of the four non­ Fig. 21. Habit and vesse1 wall thickenings anatomical variables, like earlier, shows a (white = present; black = absent).

Downloaded from Brill.com10/07/2021 07:51:36AM via free access Zhang, Baas & Zandee - Wood structure of the Rosaceae 335 latively small. No differences were found Van den Oever et al. 1981, Wheeler & Baas between evergreen and deciduous species 1991). The statistically insignificant correla­ (Table 3). tion between macroclimate and helical vessel Path analysis (Table 9) confums that only wall thickenings in the Rosaceae as revealed habit shows a significant and positive effect by path analysis may be related to the fact that on the incidence of helical vessel wall thicken­ much fewer tropical elements were included ings. In addition, macroclimate has an almost in the present study than subtropical and tem­ significant (direct path coefficient -0.1498) perate ones. If more tropical elements had and negative correlation with this character. been included, the correlation would probably As recorded before (Zhang & Baas 1992; have been significant. Some studies (Carlquist Zhang 1992), the incidence of helical vessel & Hoekman 1985; Webber 1936) also noted wall thickenings is of relatively high system­ an appreciably higher incidence of vessel atic value in the Rosaceae. Vessel wall thick­ wall thickenings in arid habitats than mesic enings are absent in most shrubby Spiraeoi­ habitats, but many exceptions exist (Baas deae and Rosoideae, whereas most arbores­ 1986; Baas et al. 1983). Moisture availability, cent Prunoideae are characterised by weil as shown by path analysis, actually shows developed helical vessel wall thickenings. little influence on the incidence of helical Therefore, it is expected that the significant vessel wall thickenings in the Rosaceae. As correlation between the incidence of helical Carlquist (1988) pointed out, if one assumes vessel wall thickenings and habit to a large that genetic information for some evolution­ extent results from systematic differences in ary changes is easier to acquire, one must helical vessel wall thickenings between sub­ conclude that vessel wall thickenings are families, rather than that it reflects an intrinsic more difficult to develop than some charac­ relation between habit and helical vessel wall ters like growth rings and changes in vessel thickenings. element size, and some groups evidently The characters which are most closely cor­ have been unable to develop vessel wall related with helical vessel wall thickenings thickenings. The incidence of vessel wall are the percentage of solitary vessels, LID thickenings was reported to be independent of ratio and vessel diameter (Table 14). In ad­ habit in the European flora (Baas & Schwein­ dition, several other characters also show gruber 1987), and no consistent trend was some weak correlations with this character. noted in the flora of the Middle East (Baas The incidence of helical vessel wall thicken­ et al. 1983). The same applies to the flora of ings increases significantly with increasing southern California (Carlquist & Hoekman vessel grouping and with more slender and 1985). narrower vessel elements. The latter is in agreement with general trends (Van der Graaff Ray width (y9) & Baas 1979). As shown in Table 15, the There are no consistent or significant rela­ mutual correlations among wood anatomical tions between ray width and macroclimate characters do not influence the ecological or moisture availability (Table 3). There are, trends significantly, but the standardised par­ however, some differences in ray width tial regression coefficient of helical vessel among trees, intermediate-sized plants, and wall thickenings on habit drops from an ear­ shrubs (Fig. 22). Trees tend to have slightly lier significant level (0.2316) to insignificant wider rays than intermediate-sized species. (0.1058), whereas the effect of phenology on Shrubs, however, showabimodal distribu­ helical vessel wall thickenings has risen to a tion and are, on the whole, characterised by significant level. wider rays than trees. As shown in Table 3, Strong correlations of helical vessel wall deciduous species have significantly wider thickenings with macroclimate were reported rays than evergreen ones in this farnily. in many phylads and floristic surveys (Baas Path analysis (Table 10) shows that ray 1973, 1986; Baas & Schweingruber 1987; width is significantly influenced by habit and Baas et al. 1983; Carlquist 1988; Carlquist & to a lesser extent by phenology. Ray width Hoekman 1985; Van der Graaff & Baas 1974; increases either with decreasing plant size, or

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% sampIes Maloideae, composed mostly of trees, or tree 35 to shrubs, are usually characterised by 1-3- 30 1 seriate rays; while most arborescent Prunoi­ 251 deae have rays over 4-seriate. Thus the rela­ I tionships between ray widtli and habit are complicated by these systematic differences ~~jI~ ~ n and partly explain the bimodal distribution for shrubs shown in Figure 22. Photinia ': n I ~i~,I!nn. ,L ~ fonns a major exception to the general trend 0' J 2 3 4 5 6 7 8 9 10 II 12 15 that deciduous species tend to have narrower width of rays (in cells) rays than evergreen ones in the Rosaceae; in Fig. 22. Habit and ray width (white = shrubs; this genus deciduous species have appreciably black = intennediate; hatched = trees). wider rays. Ray width is most elosely and positively % sampIes correlated with ray height (Table 14). In ad­ 80r- dition, a few vessel characters also show a 701 significant correlation with ray width. The 1 60 elose correlation of ray width with its height 50j seems logical. The two characters can, how­ 40j ever, sometimes vary independently in this 30 J ! family. Sorbaria, for instance, has wider 2°i (5-13-seriate) but lower (0.4-0.8 mm) rays, 101 lEIErEi' r r o i i ! I L..;, f' I i ~ I! .0 C compared with, for instance, Spiraea (Zhang 0.20.5 0.8 1.1 2 4 5 10 15 & Baas 1992; Zhang 1992). When the mutual ray height (mm) correlations among wood anatomical char­ Fig. 23. Habit and ray height (white = shrubs; acters are considered, a significant correlation black = intennediate; hatched = trees). between ray width and habit (Table 10) does not exist anymore (Table 15), but phenology still maintains a significant correlation with ray width. Ecological trends revealed by path from evergreen to deciduous species. Ray analysis for ray width are not affected signi­ width expressed by the number of cell rows ficantly by the mutual wood anatomical cor­ of the widest rays, varies greatly in this fam­ relations. ily (Zhang & Baas 1992; Zhang 1992), from In the literature, much less attention has exelusively uniseriate to 16-seriate, and is of been paid to ray than to vessel characters. great systematic value. Some genera in the Ontogenetic changes in ray size, however, shrubby Spiraeoideae and Rosoideae are are weIl documented (Carlquist 1988), and characterised by narrower than 4-seriate rays, run parallel with the trends for plant size but the remaining taxa have wider rays; the found in the Rosaceae.

Table 10. Path analysis of ray width (Y9).

X1~Y9 X2~Y9 X3~Y9 X4~Y9 P-value

X1~ 0.0447 0.0508 -.0407 -.0745 0.5552 X2 ~ 0.0198 0.1147 -.0380 -.0321 0.0831 X3 ~ 0.0078 0.0187 -.2334* -.0260 0.0001 X4 ~ -.0239 -.0264 0.0436 0.1394* 0.0475

Xl = macroclimate; X2 = moisture availability; X3 = habit; X4 = phenology. * Direct path coefficient significant if P-value < 0.05.

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Table 11. Path analysis of ray height (YlO).

Xl~YlO X2 ~YI0 X3~YlO X4 ~YlO P-value

Xl~ 0.0582 0.0586 -.0624 -.0718 0.4228 X2 ~ 0.0258 0.1323* -.0581 -.0310 0.0374 X3 ~ 0.0102 0.0215 -.3576* -.0251 0.0000 X4 ~ -.0311 -.0305 0.0668 0.1344* 0.0466

Table 12. Path analysis of ray composition (Yl1).

Xl ~Y11 X2~Yll X3~Yll X4~Y11 P-value

X1~ 0.0590 -.0345 0.0874 -.1099 0.3873 X2 ~ 0.0261 -.0779 0.0815 -.0474 0.1908 X3 ~ 0.0103 -.0127 0.5012* -.0384 0.0000 X4 ~ -.0315 0.0180 -.0936 0.2056* 0.0013

Xl = macroclimate; X2 = moisture availability; X3 = habit; X4 = phenology. * Direct path coefficient significant if P-value < 0.05.

Ray height (YlO) element length, as weil as with vessel diam­ Ray height is not significantly correlated eter. A significant correlation between ray with macroclimate or moisture availability height and vessel element length was also (Table 3), but increases significantly with recorded by Ferreirinha (1965) and Giraud decreasing plant size (Fig. 23, Table 3). In (1980), and the correlation is understandable addition, evergreen species tend to have sig­ (Carlquist 1988). Table 15 indicates that the nificantly lower rays than deciduous species significant ecological trend for ray height (Table 3). with moisture availability has to be ascribed In path analysis, ray height, like ray width, to its mutual correlation with some wood is influenced mainly by habit and phenology anatomical characters (mainly ray width and (Table 11). In addition, moisture availability vessel element length). Its relations with the also shows a significant effect on ray height other three variables, however, are not influ­ although its simple correlation coefficient enced markedly by the mutual correlations with ray height is insignificant (Tab1e 3). Ray among wood anatornical characters. height tends to decrease with decreasing mois­ Baas (1973), Van der Graaff and Baas ture availability in the Rosaceae. More or less (1974) and Van den Oever et al. (1981) re­ like for ray width, the significant relation of ported a negative correlation between ray ray height to habit may include an effect of height and latitude. This may have been caus­ systematic position. However, the decrease ed by decreasing plant size with increasing in ray height with increasing plant size is latitude in the taxa analysed by these authors. probably a generally valid trend. Ray height is most clos~ly correlated with Ray composition (Yll) ray width (Table 14). In addition, ray com­ As shown in Figure 24, the incidence of position is significantly correlated with ray juvenilistic (SU) and weakly heterogeneous height as well: with decreasing ray homogene­ (HH) rays decreases from temperate to tropi­ ity, ray height increases significantly. Mul­ cal regions, whereas the incidence of hetero­ tiple regression analysis also shows that ray geneous rays (HE) increases. The occurrence height is significantly correlated with vessel of homogeneous rays (HO) varies very litde

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ray types as SU and HH (Fig. 24). The same applies more or less to the relations of ray composition to moisture availability (Fig. 25, Table 3). The relations between habit and ray composition are much less ambiguous (Fig. 26, Table 3). Phenology does not affect ray composition significantly (Table 3). Path analysis (Table 12) indicates that habit is the most significant factor influencing ray composition. This certainly includes an im­ temperate subtropics tropics portant effect of systematic affinity because Fig. 24. Macroclimate and ray composition many shrubby Spiraeoideae and Rosoideae (white = SU; black = HE; hatched = HH; are characterised by juvenilistic (SU) or cross-hatched = HO). strongly heterogeneous (HE) rays. However, the tendency for rays to be more heterogene­ ous with decreasing plant size is probably %samples also generally valid. In contrast to the simple 60 correlation analysis, path analysis shows a 50 J significant effect of phenology on ray com­ 40 · position: evergreen species tend to have more 301 heterogenous rays than deciduous ones. Ray composition in this farnily is more 10' correlated with vessel element size (particular­ 10· ly with vessel element length) than with ray size (Table 14). The tendency in thls farnily is mesic nonnal dry for homogeneous rays to be associated with longer vessel elements. This runs counter to Fig. 25. Moisture availability and ray compo­ the Baileyan trends of xylem evolution (cf. sition (white = SU; black = HE; hatched = Carlquist 1988). Ray height is also signi­ HH; cross-hatched = HO). ficantly correlated, whereas ray width is not significantly correlated with ray composition % sampIes despite its very high simple correlation coeffi­ 30Irl ------, cient (-0.4612, Table 3). Multiple regression 15 analysis (Table 15) indicates that the correla­ 20 tions of ray composition with other wood 15] anatomical characters do not influence its ecological trends significantly, and both habit I~ j and phenology still show a significant influ­ ence on ray composition. 0 1 Baas (1986) did not find clear ecological SI,; HE HH HO trends for ray composition. Wheeler and Baas ray composltlon (1991) also showed that there is no appreci­ Fig. 26. Habit and ray composition (white = able and consistent difference in ray compo­ shrubs; black =intermediate; hatched = trees). sition between tropical and temperate floras. Shrubby and herbaceous species tend to have juvenilistic rays (Le., composed largely of with macroclimate. With the qllantification ap­ square and upright cells) (Carlquist 1988). plied for ray types (see legend of Table 1), About two thirds of the shrubby to herbace­ ray composition is on the whole not signi­ ous genera in the Spiraeoideae and Rosoideae ficantly correlated with macroclimate (Table are characterised by juvenilistic rays; in the 3), but this may be a statistical artefact be­ remaining genera there are tendencies for less cause of the parallel trends for such different heterogeneous rays.

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Table 13. Path analysis of crystals (Y12).

Xl ~Y12 X2 ~Y12 X3 ~Y12 X4 ~Y12 P-value

X1~ 0.1628* 0.0282 0.0003 -.0750 0.0367 X2 ~ 0.0721 0.0636 0.0003 -.0324 0.3483 X3 ~ 0.0284 0.0103 0.0019 -.0262 0.9749 X4 ~ -.0870 -.0147 -.0004 0.1404 0.0518

Xl = macroclimate; X2 = moisture availability; X3 = habit; X4 = phenology. * Direct path coefficient significant if P-value < 0.05.

Crystals (Y12) in temperate regions seems to be a general As reported earlier by Zhang and Baas phenomenon. (1992), crystals in the Rosaceae vary in type, The occurrence of crystals in this farnily frequency, size and the type of crystal-con­ is most cIosely related to ray composition taining cells. These aspects were not consid­ (Table 14): the incidence of crystals slightly ered in this study; only presence or absence increases with ray heterogeneity. In addition, of crystals was analysed. it is also significantly related to helical ves­ Macroclimate and habit do not show a sei wall thickenings. The mutual correlations significant correlation with the incidence of between crystals and other wood anatornical crystals (Table 3). The Rosaceae from dry characters do not influence its significant habitats have an appreciably lower incidence macroclimatic trend. However, its relation to of crystals than from either mesic or normal habit rises to a significant level, as shown in habitats. The incidence of crystals in normal Table 15. and mesic habitats is quite similar (Fig. 27). But the differences among the three levels Relative importance 0/ ecological trends of moisture availability are still insignificant Although ecology and habit are arbitrarily (Tabie 3). and very coarsely categorised in the present Unlike simple correlation analysis, path study, the above statistical analyses cIearly analysis reveals that macroclimate has a sig­ reveal significant ecological trends for certain nificant effect on the incidence of crystals wood anatornical characters within the Rosa­ (Table 13), viz., the incidence of crystals ceae. However, the percentage of explained increases significantly from temperate to variance by individual ecological factors is tropical regions. The three other factors do very low (usually 2-10%) despite a some­ not affect the incidence of crystals. Only a times highly significant correlation. The re­ few studies on the relations of crystals to maining variance may result mainly from ecology have been reported so far, but the systematic alliance, random 'noise', habit and higher incidence of crystals in tropical than in phenology. The percentage of explained vari­ ance by macroclimatic factors (latitude) in the % samples _ Rosaceae is appreciably lower than in Sym­ 70 i plocos (V an den Oever et al. 1981). 60

50 ~ Principal component analysis 40 ! - A principal component analysis of 11 30 standardised (z-score) wood anatornical char­ 20 acters (Table 16) shows that the first 5 com­ 10 ponents explain over 75% of the variance. o I '-- For the first principal component, ray char­ mesic normal dry acters (ray width, ray composition and ray Fig. 27. Moisture availability and crystals height), ring-porosity and vessel element (white = present; black ;: absent). iength have an appreciably higher loading

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Table 14. Standardised partial regression coefficients (or direct path coefficients) of each wood anatomical character ~ on other wood anatomical characters.

Yl Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 YlO Y11 Yl2 Yl -) -.1346* 0.1060* 0.0213 -.2081 * -.2000* -.0252 0.2621 * -.0109 Y2 -) -.2761 * -.0318 -.2013* 0.1884* 0.0601 -.1658* -.2473* 0.0225 0.1215 -.1361 Y3 -) -.1390* -.2425* -.0481 -.0870* 0.1664* 0.0543 -.4417* -.1261* 0.0359 0.1124 0.0740 Y4 -) -.0738 -.1269 0.6312* -.5569* -.2117 -.2559* -.0869 -.2246* -.3228* -.2434 Y5 -) 0.3848* -.6213* -.3055* 0.8399* 0.7643* 0.3399* 0.0407 0.0206 0.2994* 0.5417* 0.1959 Y6 -) 0.6914* 0.6951* -.8813* 0.9089* -.0131 0.3681 * -.2291 * -.0867 -.5137* 0.0591 Y7 -) 0.0147 0.0354 0.0364 -.0537 0.0648* -.0021 -.1015 -.0427 0.0195 0.0575 0.0413 Y8 -) -.1757* -.1191 * -.3611 * -.0792* 0.0095 0.0720* -.1239 0.0409 -.1520* 0.1903* 0.1707* Y9 -) -.2613* -.2747* -.1594* -.0416 0.0074 -.0694* -.0805 0.0633 0.5332* -.1266 0.1483 YI0 -) -.0255 0.0194 0.0352 -.0835 0.0836* -.0204 0.0286 -.1824* 0.4138* -.2613* -.0817 Y11 -) 0.2734* 0.1078 0.1135 -.1234* 0.1557* -.1242* 0.0867 0.2350* -.1011 -.2690* -.1863* Y12 -) 0.0074 -.0785 0.0485 -.0605 0.0366 0.0093 0.0404 0.1371* 0.0770 -.0547 -.1211*

The standardised partial regression coefficients of each wood anatomical characters on the others should be read in columns (from top to bottom, not from left to right). IA

Table 15. Standardised partial regression coefficients (or direct path coefficients) of each wood anatomical character on the non-anatomical WA variables, taking into account mutual correlations between all wood anatomical variables (cf. Table 14). Bulletin Y4 Y5 Y7 Y8 Y9 YlO Yll Y12 Downloaded fromBrill.com10/07/2021 07:51:36AM Y1 Y2 Y3 Xl -) -.0232 0.0494 0.0765 0.2272* -.0184 -.0471 -.0458 -.0346 0.0371 0.0884 0.2769*

X2 -) 0.0573 -.0678 -.0209 -.0562 0.1231 * -.0380 0.0489 0.0378 0.0247 -.0632 -.0217 n.

X3 -) 0.1425* -.1295* -.3110* 0.1043* 0.2048* -.1392 0.1058 -.0857 -.1673* 0.2511 * 0.1722* s.,

X4 -) -.0442 0.0360 -.1353* -.1709* -.0614 0.0116 -.1686* 0.1358* 0.1294* 0.3065* 0.1281 Vol. ------.. _------~-~-- 13 Xl = macroclimate; X2 = moisture availability; X3 = habit; X4 = phenology; Yl = ring-porosity; Y2 = vessel frcquency; Y3 = percentage of solitary vessels; Y4 = vessel (3), diameter; Y5 = vessel element length; Y6 = LID ratio; Y7 = multiple perforations; Y8 = helical vessel wall thickenings; Y9 = ray width; YI0 = ray height; Y11 = ray

composition; Y12 = crystals. 1992 via freeaccess * Significant at 0.05 level. Baas & Zandee - Wood structure of the Rosaceae 341

Table 16. Principal component analysis of wood anatomical variables: loading value.

1st 2st 3st 4st 5st Variables~ Y1 0.668 0.431 0.045 0.145 -.047 Y2 0.207 -.753 -.272 0.057 0.219 Y3 0.182 -.530 0.440 0.400 -.365 Y4 -.015 0.884 -.114 0.105 -.063 Y5 0.540 0.451 0.505 -.041 0.050 Y7 0.432 -.152 0.491 0.234 0.559 Y8 0.189 -.114 0.024 -.872 0.206 Y9 -.796 0.264 0.177 -.117 0.157 YlO -.666 0.087 0.401 0.196 0.293 Yll -.778 0.100 -.124 -.111 0.055 Y12 0.063 -.170 0.643 -.466 -.354

% of explained variance 24.7% 19.8% 12.7% 11.8% 7.1%

accumulative % 24.7% 44.5% 57.2% 69.0% 76.1% value than the other characters; for the second, or weakly heterogeneous ray composition, vessel diameter and vessel frequency contrib­ high incidence of multiple perforations and ute most; for the third, vessel element length, helical vessel wall thickenings; the Spiraeoi­ percentage of solitary vessels and multiple deae p. p. and Rosoideae group into a broad­ perforations have a higher loading value than ly scattered alliance based mainly on short the others; for the fourth, helical vessel wall vessel elements, and tall and wide rays. Cor­ thickenings have the highest loading; for the relation coefficients (r) between any two vari­ fifth, multiple perforations playamore im­ ables are accounted for in the respective prin­ portant role. The relative importance of each cipal components and are equal to the value variable is also indicated by the length of the of cos e (angle between the two variables). arrows representing the variables (Fig. 28). Ray characters and vessel element size, there­ Summary of statistical analyses fore, are the most important wood anatomical variables in this family. As shown in Fig. 28, 1) The above comparisons between path the first two components based on these 11 analysis (Tables 4-13) and simple cor­ wood anatomical characters produce three relation analysis (Figs. 8-27, Table 3) more or less recognisable groups: the Maloi­ clearly show that the latter usually cannot deae, the Spiraeoideae p.p. together with the exact1y reflect intrinsic relations between Rosoideae, and the Prunoideae, but excep­ wood anatomical characters and ecological tional cases still exist (a few taxa in the Ros­ factors, habit, and phenology, and some­ oideae extend into the Maloideae group for times even can be misleading (like in ring­ instance). The tribe Quillajeae do not gather porosity, vessel diameter, vessel element into an alliance, but instead scatter into the length, ray composition and crystals) since Prunoideae and the Maloideae near the centre. the four variables show close mutual cor­ In the Prunoideae the tropical tree genus relations with one another. For the validity Pygeum is represented by a cluster of the of any ecological trends, therefore, suit­ most outlying points mainly on account of able statistical analysis (multiple regres­ large vessel diameter and low vessel frequen­ ~ion analysis for instance rather than sim­ cy; the Maloideae form a tight group on ac­ ple correlation analysis) must be carried count of narrow and low rays, homogeneous out in ecological wood anatomy.

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Component 2

,----, -, ,~--,- '----,----r ,-----,---,----~- ~' I ~ Vessel diameter I I 5 -,

o 0 00 p Vessel 3 Ring-porosity element length

Ray width •• 1.-. l

, ~ :'-~'1 , ...... 00 0 o -1 ... o ,. Mu~rle perforations ~ o o

• 0 o 0 / j

S+R 00 -3 ~

-5

-5 -3 -1 3 Component

Fig. 28. Biplot for first two principal components. P = Prunoideae; M = Maloideae; S + R = Spiraeoideae + Rosoideae.

2) Most ecological trends revealed by path anatomical characters. Some characters analysis are in agreement with the general (viz. vessel diameter and helical vessel trends found in other phylads or regional wall thickenings) are more dependent on floras, and are a reflection of intrinsic re­ macrodimate, while others (viz. vessel lations between wood anatomical charac­ element length and ray height) are more ters and ecology. The ecological trends dependent on moisture availability. for vessel frequency and ray height, how­ 4) Quantitative characters such as vessel ele­ ever, have to be ascribed to their correla­ ment size and vessel frequency show eco­ tion with other wood anatomical charac­ logical trends more dearly than qualitative ters. ones (ring-porosity, helical vessel wall 3) Macroclimate and moisture availability thickenings, vessel grouping, ray com­ show very different effects on some wood position and crystals). Vessel characters

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show stronger ecological trends than ray and fibre characters related to mechanical characters. Both vessel diameter and ves­ support were left out of this analysis. We are seI element length show significant eco­ fully aware that any functional interpretations logical trends, but the LID ratio is inde­ without experiments are highly speculative. pendent of ecology. Ray height shows Dur interpretations are based mainly on the more appreciable ecological trends than generally accepted theories on water transport ray width, as weIl as ray composition. (Milburn 1979; Zimmermann 1983; Zimmer­ 5) Habit has a significant relation with most mann & Brown 1971). wood anatomical characters in the Rosa­ From tropical, via subtropical to temperate ceae. But the relation, to differing extent, regions, or with decreasing moisture avail­ includes systematic differences since habit ability, the Rosaceae tend to size reduction is closely related to systematic differences (from tall trees to shrubs or herbs), and to at the subfarnily level in Rosaceae. deciduousness. Dwarfing (Aloni 1991) and 6) Phenology does not influence any vessel deciduousness (Carlquist 1988) are also ways related characters except vessel diameter, of adapting to drought and freezing. These but ray characters are all significantly in­ adaptations may be more imponant than fluenced. wood anatornical adaptation (Carlquist 1988), 7) LID ratio is most closely correlated with and may have reduced adaptive pressure on most vessel characters (viz. vessel element wood structure. As stressed by Baas et al. length, vessel diameter, vessel frequency (1983) and Carlquist (1988), therefore, eco­ and the percentage of solitary vessels). logical trends in wood structure should be Next is vessel element length which is also viewed in combination with other aspects of most closely correlated with the incidence plant biology. of multiple perforations, vessel frequency, Vessel diameter is probably the most im­ ring-porosity and vessel diameter. Ray portant variable for the efficiency of water characters are mainly correlated among conduction (Baas 1976, 1986; Carlquist themselves, but some correlations between 1988; Zimmermann 1978,1983). Largerves­ ray characters and vessel characters were seI diameter contributes to much greater con­ also found. Principal component analysis ductive efficiency, but at the same time de­ shows sirnilar relations among wood ana­ creases the safety due to its inverse relation to tornical characters and produces three more vessel frequency (Zimmermann 1983). The or less recognisable groups. tropical genus Pygeum in this farnily can 8) The differences in vessel element size and exemplify this. Wide vessels apparently adapt ray size recognised by Zhang and Baas to conduction of large volumes of water. Al­ (1992) between deciduous and evergreen though vessel diameter is cIosely related to groups of Photinia should be considered the efficiency and safety of water transport as systematically highly relevant, since (Baas 1986; Carlquist 1988; Zimmermann they ron counter to the general trends in 1983), vessel diameter itself actually is not the Rosaceae. deterrnined by water availability in the Rosa­ ceae. Instead, it is mainly controlled by ma­ Functional, developmental and systematic croclimate which incIudes temperature, light considerations intensity and seasonality. It suggests that these aspects are more important in control­ Functional aspects ling vessel diameter than moisture availabil­ The ecological trends, to differing extent, ity. Temperature and light intensity are cIose­ have been interpreted as the results of func­ ly related to transpiration rate, as weH as tional adaptation to environmental factors to freezing (Carlquist 1988; Zimmermann (Baas 1986; Baas & Schweingruber 1987; 1983). A high transpiration rate in conditions Carlquist 1975, 1988). of high temperature and light intensity (tropi­ Water transport through vessels is one callowland for instance) requires the conduc­ main function of secondary xylem. Therefore, tion of large amounts of water, which needs vessel-related characters were emphasised highly efficient conduits, or wide vessels.

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Risks imparted by frosts are absent. There­ increases, while vessel diameter decreases, fore, the need for high conductive efficiency just as found in the Rosaceae. in such a macroclimate constitutes a primary Ring-porosity is of importance for the adaptive press ure, while the safety of water combined efficiency and safety of sap trans­ transport is of secondary importance. In a port (Zimmermann & Brown 1971). There­ low temperature macroclimate, however, the fore, it is understandable that the develop­ xylem sap can freeze in winter, and a rela­ ment of ring-porosity is the result of adapta­ tively low transpiration rate in summer and tion to seleetive pressures (Aloni 1991; Carl­ spring does not require highly efficient con­ quist 1988; Wheeler & Baas 1991). Path anal­ duits for water transport. Therefore, the safe­ ysis, however, reveals that both macroclimate ty of water transport constitutes a primary and moisture availability themselves do not adaptive pressure. Narrowing of vessels show significant direct effeets on ring-poros­ from tropical to temperate regions may thus ity in the Rosaceae. Their effects are largely be the result of functional adaption for higher indireet, mainly through plant habit (or plant safety of water transport (Baas 1986; Carl­ height) sinee unfavourable ecologieal condi­ quist 1988; Zimmermann 1983). Vessel fre­ tions result in the reduction of plant height. quency was considered to be of primary im­ As shown in Table 4, with deereasing plant portance in the safety of water transport height, plants tend to be ring-porous. In ring­ (Baas 1986; Carlquist 1988; Zimmermann porous species, extension growth frequently 1983). Significant correlations of vessel fre­ stops early in the growing season while eam­ quency with ecology, however, actually re­ bial activity continues fur a long period sult to a large extent from its correlative con­ (Aloni 1991; Savidge & Wareing 1981). In straints imposed by vessel size in the farnily. other words, ring-porous speeies generally Therefore, vessel frequency may play an ap­ show smaller growth intensity than diffuse­ preciably smaller role in functional adaptation porous speeies (Lode wiek 1928). The dose than vessel size. Carlquist (1980) and Zim­ relation between habit (or plant height) and mermann (1978) considered greater vessel ring-porosity found in this farnily ean thus be frequency as a potential advantage of greater well explained. Digby & Wareing (1966) and redundancy. Wareing (1951) also found that the cessation of extension growth is eorrelated with the Developmental aspects transition from earlywood to latewood. Ring­ The effects of environmental factors on porosity associated with limited plant growth wood differentiation are complex, involving was reported by Lipschitz and Waisel (1970a, direct and indirect aspects. Environment might 1970b) in Populus euphratica where vigorous affect wood differentiation through shoot tree growth is assoeiated with the formation growth (Denne & Dodd 1981). Aloni (1987) of diffuse-porous wood, while the limitation also suggested that environment influences of height growth under unfavourable condi­ vessel size partly through plant height and as­ tions results in the formation of ring-porous sociated auxin gradients along the plant axis. wood. Adesmia horrida (Roig 1986) was These gradients are critical for vessel differ­ also reported to vary from semi-ring-porous entiation (Aloni 1987, 1991; Sachs & Cohen wood formed in favourable conditions to 1982). A high auxin level, whieh aeeelerates ring-porous wood when limited by water vessel differentiation, results in the formation stress and higher altitude. of numerous narrow vessel elements (Aloni & Zimmermann 1983). This hypothesis may Systematic considerations weIl explain the eorrelations between plant The evaluation of ecological trends also habit and vessel size in this farnily revealed helps to assess the systematie value of vari­ by path analysis. The deerease in plant height ous wood anatomical characters. Any appre­ reduces the distanee of basipetal auxin trans­ eiable eeologieal trends would more or less port from young leaves. Auxin levels may, reduce the systematie value of wood anatom­ therefore, be relatively high. In other words, ical characters (Carlquist 1988). However, with decreasing plant height, vessel frequency this does not necessarily mean that wood ana-

Downloaded from Brill.com10/07/2021 07:51:36AM via free access Zhang, Baas & Zandee - Wood structure of the Rosaceae 345 tomical characters which do not show eco­ to result in a very tentative wood evolutionary logical trends are of high systematic value. scenario for the farnily. This scenario is far Ring-porosity in the Rosaceae is not sig­ from complete and is here only presented as a nificantly influenced by ecology. It rarely oc­ speculative hypothesis to be tested in future curs in Rosaceae and is generally of system­ studies. atic value only at or below the genus level The ancestral 'Proto-Rosaceae' were pre­ (Zhang & Baas 1992; Zhang 1992). Amyg­ sumably characterised by diffuse-porosity; dalus and Armeniaca can be distinguished almost exclusively solitary, narrow and num­ from other members of the Prunus s.l. alli­ erous vessels; absence of helical vessel wall ance on account of this character. thickenings; fibres with distinctly bordered Significant ecological trends of vessel fre­ pits in both the radial and tangential walls; quency, although caused by mutual correla­ scanty axial parenchyma, and strongly het­ tions with vessel size, remove it from the list erogeneous rays. They were diploid shrubs of systematically relevant characters in this with dry dehiscent fruits. In modern Rosa­ farnily. The fact that there are no appreciable ceae many of the wood anatornical features of ecological trends for vessel grouping confirms these Proto-Rosaceae still persist in the tem­ our earlier evaluation that percentage of soli­ perate to subtropical (sometimes tropical mon­ tary vessels has a high value at the subfarnily tane) Rosoideae and Spiraeoideae. Within the level in the Rosaceae (Zhang & Baas 1992; forerunners of these subfarnilies only Iirnited Zhang 1992). Apparently, both vessel diam­ wood anatornical diversification occurred: ad­ eter and vessel element length are very sensi­ justments in vessel diameter, origin of ring­ tive to ecology so that they are of litde sys­ porosity, helical vessel wall thickenings, libri­ tematic value. However, LID ratio is more form fibres, and some degree of vessel group­ meaningful systematically than either vessel ing arose independently from each other in diameter or vessel element length because a lirnited number of taxa, sometimes in paral­ this ratio is independent of ecology. Due to lel development, and possibly in response to the very sporadic occurrence of multiple per­ adaptive pressures brought about by climatic forations in the Rosaceae, this character is of changes or relating to habit and phenology. no systematic value despite its independence Since the timing of such changes is unknown, of ecology. Helical vessel wall thickenings and thus cannot be related to palaeoclimatic show only weak ecological trends and remain events it is impossible to give a more detailed of considerable systematic value (Zhang & and meaningful interpretation. Baas 1992; Zhang 1992). Both ray width and The origin of the Maloideae, presumably ray composition are independent of ecology, through alloploidy, was associated with re­ and are more useful for systematic purposes duction in ray size, an increase in parenchy­ than ray height in Rosaceae. A weak but sig­ ma abundance and ray homogeneity, and nificant macroclimatic trend for incidence of attaining tree stature. Ecological explanations crystals hardly affects the diagnostic value to account for these changes are redundant, of crystals. Especially the different types of because the Maloideae did not enter ecologi­ crystals and different cell types in which they cal ranges different from those of the Spi­ are deposited is of great taxonomic signifi­ raeoideae and Rosoideae. The predorninance cance (Zhang & Baas 1992; Zhang 1992). of helical thickenings in the Maloideae may In summary, the relations of wood ana­ point to (a) diploid ancestor(s) which had tomical characters to ecology confirm previ­ already acquired this feature. ous evaluations of the systematic value of The Quillajeae with their presumably prim­ these characters. itive floral and fruit morphology, but high, and possibly derived chromosome numbers, A tentative wood evolutionary scenario were probably an early off-shoot from the Proto-Rosaceae with as specialisation helical The weak, but yet significant ecological thickenings, and relatively abundant paren­ trends in the Rosaceae can be combined with chyma. The former features points to a sea­ the earlier phylogenetic analysis (Zhang 1992) sonal climate for the early Quillajeae, despite

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the present extension into tropical regions of distribution area of the Angiosperms in the some of its genera. early Tertiary. The arborescent Prunoideae acquired the most derived and diverse wood anatomical Acknowledgements attributes. Vessel grouping (in response to The authors would like to thank Prof. Dr. demands for increased hydraulic safety or as C. Kalkrnan for his helpful comments on the an autonomous specialisation associated with evolutionary scenario of the Rosaceae. Thanks changes in fibre pitting, cf. Carlquist 1984a), are also due to al! who kindly provided this and reduction in size and distribution of bor­ study with the sampIes or rnicroscopic slides dered fibre pits are common to the entire sub­ (see Zhang & Baas 1992; Zhang 1992). This family. Radiation into tropicallowland habi­ study was supponed by a grant to the first tats resulted in increased vessel diameter and author from the Royal Dutch Academy of reduced vessel frequency in Pygeum and Science (KNA W). Laurocerasus B. The associated increase in vessel element length implied areversal from References the general evolutionary trend (Bailey & Tup­ Aloni, R. 1987. Differentiation of vascular per 1918). Ring-porosity evolved in the tem­ tissues. Ann. Rev. Plant Physiol. 38: perate to mediterranean Amygdalus and Ar­ 179-204. meniaca as a strategy for combined hydraulic Aloni, R. 1991. Wood formation in decidu­ efficiency and safety. ous hardwood trees. In: A. S. Raghaven­ The above scenario tacitly assumes a dra (ed.), Physiology of trees: 175-197. Laurasian origin of the Rosaceae and subse­ John Wiley & Sons, New York. quent radiation into different (now) tropical Aloni, R. & M. H. Zimmermann. 1983. The regions. Such an origin has, however, been control of vessel size and density along rejected by Kalkman (1988) and several other the plant axis - a new hypothesis. Differ­ authors. Instead an early Gondwanan origin entiation 24: 203-208. has been advocated on the basis of some Baas, P. 1973. The wood anatornical range otherwise inexplicable distribution pattern of in Ilex (Aquifoliaceae) and its ecological extant genera. A Gondwanan origin would and phylogenetic significance. Blumea 21: imply that the tropical character syndrome of 193-258. wide, long vessel elements might have origi­ Baas, P. 1976. Some functional and adaptive nated very early in the evolutionary history of aspects of vessel member morphology. the Rosaceae, and that the predominance of In: P. Baas, A.J. Bolton & D.M. Catiing extant Northern Hemisphere representatives (eds.), Wood structure in biological and with numerous, narrow vessels represent a technological research: 157-181. Leiden later adaptation for greater hydraulic safety in Botanical Series No. 3, Leiden University the temperate seasonal climate. Press, Leiden. Since the Rosaceae are doubtlessly an old Baas, P. 1982. Systematic, phylogenetic and family (wel!-recognisable Prunus wood has ecological wood anatomy - history and been reported from the Eocene by Cevallos­ perspective. In: P. Baas (ed.), New per­ Ferriz and Stockey, 1990), the wood ana­ spectives in wood anatorny: 23-58. Mar­ tomical scenario based on an analysis of ex­ tinus Nijhoff / Dr. W. Junk Publishers, tant diversity pattern cannot shed light on the The Hague. alternatives for a Laurasian or Gondwanan Baas, P. 1986. Ecological patterns in xylem origin. In the Cretaceous and early Tertiary anatomy. In: T.J. Givnish (ed.), On the tropical conditions extended over a much economy ofplant form and function: 327- wider latitudinal range, and specialisations 349. Cambridge University Press, Cam­ like ring-porosity, helical vessel wall thick­ bridge. enings, and elaborate vessel grouping were Baas, P. & S. Carlquist. 1985. A compari­ exceedingly rare (Wheeler & Baas 1991). son of the ecological wood anatomy of the The Proto-Rosaceae wood type must have floras of southern California and Israel. been fairly common throughout the entire IAWA Bul!. n. s. 6: 349-353.

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