IAWA Bulletin n.s., Vol. 8 (3),1987 245
ECOLOGICAL TRENDS IN THE WOOD ANATOMY OF TREES, SHRUBS AND CLIMBERS FROM EUROPE
by
Pieter Baas and Fritz H. Schweingruber Rijksherbarium, P.O. Box 9514, 2300 RA Leiden, The Netherlands and Eidgenössische Anstalt für das forstliche Versuchswesen, CH-8903 Birmensdorf, Switzerland
Summary Ecological trends for occurrence of certain established on a floristic basis. It is suggested vessel, tracheid and fibre characteristics. have that the ecological trends are the result of se been analysed for 505 species (belonging to lection for specialised wood anatomical fea 221 genera and 71 families) from Europe, Cy tures such as simple perforation plates, vascular prus, and Madeira. Macroclimatic gradients tracheids, and different vessel size classes in the from boreal, via temperate to mediterranean mediterranean region and dry and warm sites in are strongly related with a decreasing incidence general, and that primitive features such as scala of scalariform perforations, (almost) exclusively riform perforations, solitary vessels, and fibre solitary vessels, and fibre-tracheids (i. e., fibres tracheids are not selected against in cool boreal with distinctly bordered pits). In this sequence and mesic habitats. For some characters macro the incidence of different vessel size classes climatic factors (chiefly temperature) seem more (vessel dimorphism) and vascular tracheids in important than moisture availability, for others creases. Ring-porous tendencies and spiral ves moisture availability seems equally important. sei thickenings have their peaks in the temper The biological significance of the reported ate zone. The subtropical flora of Madeira trends is discussed in terms of safety and effi shows low values for the percentage of species ciency of xylem sap transport, and of evolution with any of the above attributes. ary correlative constraints. In the graded series from dry (including wet Key words: Vessel perforations, vessel distribu saline), via normal to mesic, the incidence of tion, tracheids, fibres, ecology, Europe. scalariform perforations strongly increases and that of vascular tracheids decreases. Other at Introduction tributes show a weaker or ambiguous relation In the final stages of the preparation of an ship with moisture availability: incidence of extensive atlas of the wood anatomy of trees, different vessel size classes and spiral vessel shrubs, and climbers from Europe, Cyprus, and thickenings decreases; incidence of fibre-tra Madeira (Schweingruber, in preparation) de cheids increase in dwarf shrubs and normal scribing and picturing c. 600 species of woody shrubs, but decreases in trees; ring-porosity and gymnosperms and angiosperms, an analysis of (alm ost) exclusively solitary vessels are inde ecological trends in the wood anatomy of the pendent of moisture availability. 505 species of native dicotyledonous trees, There is also a relationship of some of these shrubs, and climbers described has been carried wood anatomical attributes with plant habit. out to be incorporated as a special chapter The incidence of species with exclusively scala (Baas, in Schweingruber, in preparation). These riform perforations, ring-porosity, and (alm ost) species represent 221 genera and 71 families. exclusively solitary vessels, decreases gradually The results of this analysis seemed to justify a in the series from trees via shrubs to dwarf precursory publication in this Bulletin. shrubs, while the reverse is true for species with The analysis of wood anatomical trends in different vessel size classes, and vascular tra the ecologically and taxonomically diverse cheids. Fibre-tracheids show no clear relation European flora is a complement to recent anal ship with plant habit. Climbers in the European yses of local or regional floras from Israel (Baas woody flora score relatively low for incidence et al., 1983; Fahn et al., 1986; Baas &Carlquist, of scalariform perforations and solitary vessels, 1985), southern California (Carlquist & Hoek but high for ring-porous tendencies, different man, 1985), and Australia (Carlquist, 1977). vessel size classes, and spiral thickenings. Inci The present analysis is based on many more dence of fibre-tracheids and vascular tracheids species than these earlier studies, but is limited is more or less similar to that in erect shrubs. in its scope to qualitative characters of per Within ecologically diverse genera or families forate and imperforate tracheary elements. very little can be traced of these salient trends (text continued on page 259)
Downloaded from Brill.com10/09/2021 04:50:05AM via free access 246 IAWA Bulletin n.s., Val. 8 (3),1987
Table 1. Species studied and their ecological and wood anatomical attributes.
Legend: Macroclimate: b = boreal; t = temperate; m = mediterranean; s = subtropical oceanic (i.e., from Madeira); * = montane (j.e., highest localities at or above the timberline). See text for the classification of species with altitudinal or latitudinal ranges overlapping several categories. Moisture availability: d = dry; dh = saline (i.e., physiologically dry); n = normal; m = mesic. See text for classification of species covering several ecological categories. Habit: ds = dwarf shrub; s = shrub; t = tree; cl = climber, liana or scrambling shrub; ** = stern parasite. See text for classification of species with intermediate habit or covering more than one habit category. + = character present; ± = character intermediate or poorly developed (in case of perforation plates: mixed simple and scalariform perforations present; in case of ring-porosity: wood semi-ring-porous or semi-ring- to diffuse-porous); +/- = fibre-tracheids and libriform fibres present; - = character absent.
-0 >, ~ '" & .... .~ '(j) -0'" os '" Ol '(j) -5 ~ Z' ~ "i ~ os Q) .; '" 0 '" -0'" -5 .... +' o '" '" Q) '0) os +' os Ei>, ~ Ei ~ t> ~ '" bD ..<:: .b .... 0 'U) ca Q) ~ " Q) o·~ '"Q).~ I::: "~ E <.:;+' o '-"> ~C/) E .-4 I::: .... .~ os o-... _rn •U'l ,...Q.) Q)cn > a c "o E ...... Q) ~ '3 Q) .... ~ Q) '" ;<;:l ~~ 0..Q)::l~", os .~ Species "os '0 os .... • .....-4 ...... " ,,0..... " ~ " Q) ~ ~] ~~ '"os '"os Ei Ei ..<:: "'0.. .~ > (1) '"C1 ~-:5 t;: > > Aceraceae Acer campestre t d t + Acer granatense m* n + Acer heldreichii m n t + Acer hycranum m n t + Acer monspessulanum m n t + Acer obtusatum m n t + Acer opalus t n t + Acer platanoides m t + Acer pseudoplatanus m + Acer sempervirens m n + Acer tataricum m n t ± ± + Amaranthaceae Bosea cyprea m m cl Anacardiaceae Cotinus coggygria m d s + + + + Pistacia atlantica m d + + + + Pistacia lentiscus m d t ± + + + Pistacia terebinthus m d t + + + + Rhus coriaria m d s + + + + Apocynaceae Nerium oleander m m ± Aquifoliaceae Ilex aquifolium m + + + Araliaceae Hedera helix t n cl ± ± ± + Asc1epiadaceae Periploca graeca m n cl + + ± Periploca laevigata m d s ± ± ± ±
Downloaded from Brill.com10/09/2021 04:50:05AM via free access IAWA Bulletin nos"~ Vol. 8 (3),1987 247
(Table 1 continued) VI "d & ~ ,~ VI 'S os VI "d 'S -5 ~ ~~ ~ ; VI os "' 0 VI '~ o VI VI "d -5 .b ~ S VI ßS>.Q) Q) 'S ..... r;- > VI b.O ..s:: <.> ... § VI I':: <.> 1: ''; Q) O'~ ..., E ~ ~ (1)..... ~ ..., ""...,,~ --00· .... <.> os ~ I':: VI > I':: ... ta o ...... Q) Q) ...... Q) ~ E Q) ... VI ~ t; VI ~ & ~ os ....: Q) '3 <.> b.O 'fjJ Species os '0 .;~ :"ü ~gj '1""4...... " ..0... VI ~ <.> Q) I':: Q) >< "os S S ..s:: VlI'l. 'i: > Q) :.s'ü ~.s t-+= > ~ Berberidaceae Berberis aetnensis m* n s + + + + Berberis cretica m d s + + + + Berberis hispanica m m s + + + + Berberis vulgaris t d s + + + + Betulaceae Alnus cordata m m + Alnus glutinosa t m + ± ± Alnus incana t m t + ± ± Alnus orientalis m* m t + ± ± Alnus viridis t* m s + Betula etnensis m* n + Betula humilis b m ds + Betula nana b m ds + Betula pendula b n t + Betula pubescens b m t + Boraginaceae Echium angustifolium m n ds Echium nervosum s d s Lithodora fruticosa m d ds ± + + + Lithodora hispidula m d ds ± + + ± Moltkia petraea m d ds ± + + + Onosma erecta m d ds ± + ± Onosma fruticosa m d ds + + + Onosma graeca m d ds ± + ± Buxaceae Buxus balearica s d t + + + Buxus sempervirens t d t + + + Capparidaceae Capparis spinosa m d ds + ± Caprnoliaceae Lonicera alpigena n s ± ± ± ± + + Lonicera caerulea t* m s ± ± ± ± + + Lonicera caprifolium t m cl ± ± ± ± + + Lonicera etrusca m n cl ± ± ± ± + + Lonicera implexa m n cl ± ± ± ± + + Lonicera nigra t n s ± ± ± ± + + Lonicera periclymenum m cl ± + + Lonicera pyrenaica m* d ds ± ± ± ± + + Lonicera xylosteum t n s ± ± ± ± + + Sambucus maderensis s m Sambucus nigra m s ± ± ± Sambucus racemosa t m s ± ± ± Viburnum lantana t d cl + + + + Viburnum opulus n s + + + +
Downloaded from Brill.com10/09/2021 04:50:05AM via free access 248 IAWA Bulletin n.s., Vol. 8 (3),1987
(Table 1 continued) Vl "CI ~ ~ ~ Vl .Ci) :Ei ",.~ - "CI ,.c: 'Z' ~.: ca .Ci) <> .0; 00'0 ~ ~ Vl ,.c: ...,Q) '" o rn rn _ "CI <> ...,... > .Ci) '" e ;g E .5;... Q) ~b/) ,.c: ...,... <> ... 0 Vl ~- > rnc:;:: <> '" ·C '" Q) o·~ 0 ..., ] '" ...... , ... -- ~...:. Q,).~ ... 0 00· .... c:: eil > c:: ... a .: <> ..., Q) 0 ....~ '"... ~ '" E ..., d, '"5 <> ... Vl .~ <> b/) ~ ~ ~ ~ ca~ <> Species ·0 .!~ tfJ 'ü if: ~ .~.~ ... Vl Vl .: Q) ~ .~_ ~,.c: .J:J ~ '" Q) e'" e ,.c: ~~ ·C > (1) ""C:j u rn~ t+= '"> '"> (Caprifoliaceae) Viburnum tinus m n s + + + + Caryophyllaceae Arenaria ciliata b* n ds + Dianthus hispanicus m d ds ± ± + Dianthus rupicola m d ds ± ± + Silene pseudovelutina m n ds + Celastraceae Euonymus europaeus t m s ± + ± + +/- Euonymus latifolius t m s ± + ± + +/- Euonymus verrucosus m d s ± + ± + +/- Maytenus dyandri s n +/- Chenopodiaceae Arthrocnemum fruticosum m dh ds + + Arthrocnemum glaucum m dh ds + + Arthrocnemum perenne m dh ds + + Atriplex glauca m dh ds + + Atriplex halimus m dh s + + Chenopodium vulvaria m dh ds + + Halimione portulacoides m dh ds + + Halocnemum strobilaceum m d ds + + + Haloxylon articulatum m dh ds + + Noaea mucronata m d ds + + Salsola genistoides m d ds + + + Salsola verticillata m n ds + + + Suaeda pruinosa m dh ds + ± + Suaeda vera m dh ds + + + Cistaceae Cistus albidus m d ds + + + Cistus crispus m d ds + + + Cistus ladanifer m n ds ± + ± + + Cistus laurifolius m n ds ± + ± + + Cistus monspeliensis m d ds + + + Cistus salvifolius m d ds + + + Fumana ericoides m d ds ± + ± + + Fumana procumbens m d ds ± + ± + + Halimium atriplicifolium m d ds ± + ± + + Halimium ocymoides m d ds ± + ± + + Halimium viscosum m d ds ± + ± + + Helianthemum lavandulifolium t d ds ± + ± + Helianthemum nummularium d ds ± + ± + + Heliantliemum oelandicum t d ds ± + ± + Helianthemum squamatum t d ds + + Cneoraceae Cneorum tricoccon m d ds ± + + +
Downloaded from Brill.com10/09/2021 04:50:05AM via free access IAWA Bulletin n.s., Vol. 8 (3),1987 249
(Table 1 continued) '"C.:;;'" & c:s~ _M~ _ '"C'" ..<:: :.c ~~:. '; .:;; ~
Downloaded from Brill.com10/09/2021 04:50:05AM via free access 250 IAWA Bulletin nos"~ Vol. 8 (3),1987
(Table 1 continued) ~ "C'" ;.:::: Q ~ '0; :.a <1S'~ ~ "C'" ..c <1S -;;-~ ~ ~ '0; <> ~ <1S ., '~ 00'0 ~ ~ "C ..c .., >, 0 rJ'J. rJ'J ...... ,~'" +' <1S +' <1S > ., " <1S S ~ :;:..§»~ ~bIi .b <> .., 0 cJ'J a:s ,...... 00 c ..c '':: ., O'~ e,,-,,~~ Q) ...... , ] .., <.:;+' "<1S +' ,~ <1S o cn· .... cr/l >c <1S I:: .., .., ~ ...... tI.I <1)<1) ...... <1) .b ., "..,0 .B Q, '3 ,~ bl) ~E ~ ~ ~~ .., 0 ~~ cf/Jufeo:S· .... · .... '
Downloaded from Brill.com10/09/2021 04:50:05AM via free access IAWA Bulletin n.s., Vol. 8 (3),1987 251
(Table 1 continued) ...,., & ~ ~ ., '$ ",.~ - ..., ~ Z'~ ~ Qi ., '$ -5 Q) ~ö ~ ~ ..<:: ..., 'e; ..., (,) .,., - '$ ., .b'" ~ S ~ E .5» ~ ~b11 (,) '" ... 0 .,- "c:: .b Q) 0 -5 '0:: ~ O'~ '"... ~~ ~ Q) ...... , ..., (,) ... ""..., 0 r/l'1""'I C CIl > c:: ta c:: 0 ...,::l ,~...... '" 0. .b Q) ..., (,) ... ., ., "3(,) (,) bII ~ ~ ~ ~ ~~ ';J '0 ~'t: tf.I 'ü ~ ~ .=:.~ ... ., Species ~ ~ Q) ,S ..0 ., ., S'" S ..<:: .,0. ... ~ ~ ;a'ü ~Z t;:l > > (Euphorbiaceae) Euphorbia squamigera m d ds Fagaceae Castanea sativa t n t ± + ± + + Fagus orientalis m n t ± ± ± +/- Fagus sylvatica t n t ± ± ± +/- Quercus alnifolia m* d t + ± + Quercus cerris m n t + + + + Quercus coccifera m d t + ± + Quercus congesta m n t + + + + Quercus faginea m n t + + + + Quercus frainetto m n t + + + + Quercus fruticosa m d t + + + + Quercus ilex m d t + + Quercus infectoria m m t ± + + + Quercus petraea n t + + + + Quercus pubescens m d + + +. + Quercus pyrenaica m n t + + + + Quercus robur t n t + + + + Quercus suber m m t + ± + Quercus trojana m d t + + + + Frankeniaceae Frankenia laevis m dh ds + + + Frankenia thymifolia m dh ds ± + + Globulariaceae Globularia alypum m d ds ± ± ± + + ± Glob ularia cordifolia t d ds ± + ± + + ± Globularia nudicaulis t* d ds ± + ± + + ± Lytanthus salicinus s n ds ± ± ± + + ± Grossulariaceae Ribes alpinum t* m s + ± ± +/- Ribes petraeum t* m s + ± ± ± ±/- Ribes uva-crispa t n s + ± +/- Hippocastaneaceae Aesculus hippocastanum m m + Hypericaceae Hypericum androsaemum m m ds ± +/- Hypericum balearicum m d s ± ± +/- Hypericum empetrifolium m d ds ± ± +/- Hypericum foliosum s n ds ± ± +/- Hypericum perforatum n ds ± ± +/- Juglandaceae Juglans regia t n ± ± Labiatae Ballota hirsuta m n ds ± ± + +
Downloaded from Brill.com10/09/2021 04:50:05AM via free access 252 IAWA Bulletin n.s., Vol. 8 (3), 1987
(Table 1 continued) "1:1'" & ~ .~ '03 ,g '" "1:1'" ..<:: Z;.=: 'Q) 'öl '03 <.> ~ ~ «I '0; '" 0 '" "1:1 {l 0", '" '" .h -Cl) .~Cl) «I ~ ß e >. ~ <.> ~ e.. §'" 0; ta Q) ~ '" bD ..<:: .h Cl) o·~ '"Q)...... I:l <.>~ ] <,;;,+> o --> .. E<.> =C/J > I:l .. «I I:l o 6 $ 0; ~ ~ ,..... Q) -+f Cl) E '5 ~ «I.>: Cl) :; t; .. <.> .. <.> .~ Species «I '0'" ,d~ ~ ~~ ~ ~ ...... c ~ <.>Cl) = Q) ~ ...... () '"«I '"«I e e ..<:: ",p. 0;:::: > Cl.) "'t:S ~.z t;: > > (Labiatae) Ballota integrifolia m n ds ± ± + + Hyssopus officinalis m n ds + + + Lavandula angustifolia m d ds ± ± + + Lavandula dentata m d ds ± ± + + Lavandula lanata m d ds ± ± + + Lavandula multifida m d ds ± ± + + Lavandula stoechas m d ds ± ± + + Marrubium supinum m m ds + + + Marrubium vulgare m d ds ± + + + Micromeria sp. m d ds + + + Origanum syriacum m d ds ± + + Origanum vulgare t d ds ± ± + + Phlomis fruticosa m d s ± ± ± + Phlomis lychnitis m d ds ± ± ± + Phlomis purpurea m d ds ± ± ± + Phlomis samia m d ds ± + + Prasium majus m n cl ± ± + Rosmarinus officinalis m d ds ± ± + + Salvia argentea m d ds ± + + Salvia cypria m d ds ± + + Salvia glutinosa t m ds ± + + Salvia lavandulifolia m d ds ± + + Satureja obovata m d ds ± ± ± + Sideritis hyssopifolia m d ds + + Sideritis linearifolia m d ds ± ± + Sideritis massoniana s n ds + + Sideritis spinulosa m d ds ± + ± + Teucrium betonicum s n ds ± + + Teucrium chamaedrys d ds ± ± + ± + Teucrium creticum m d ds ± + + + Teucrium divaricatum m d ds ± + + + Teucrium fruticans m n s ± + + Teucrium montanum t d ds ± ± + ± + Teucrium polium m d ds ± ± + Thymus capitatis m d ds ± + + + Thymus mastichina m d ds ± + ± + Thymus membranaceus m d ds ± + + + Thymus serpyllum t* d ds ± + ± + Thymus tomentosus m d ds ± ± + Thymus villosus m d ds ± + ± + Thymus vulgaris m d ds ± + ± + Thymus zygis m d ds ± + ± + Lauraceae Laurus azorica s m t ±
Downloaded from Brill.com10/09/2021 04:50:05AM via free access IAWA Bulletin n.s., Vol. 8 (3),1987 253
(Table 1 continued) UJ ~ c .~ UJ "".e;; ~ UJ ~ .e;; ..<:: Z'~ Q) UJ "" ~ UJ 0 UJ ~ " o UJ UJ -5 Jl .~ ~ II ~ Q) ""'S =.... §UJ t> =>. ~ UJ bIi ..<:: b .~ :§~ UJ " o·~ +' Q) .~I': "o:s E ~ ",,+' E .~ ~ '{j} UJ _ ;> I':
Downloaded from Brill.com10/09/2021 04:50:05AM via free access 254 IAWA Bulletin nO SO, Vol. 8 (3),1987
(Tab1e 1 continued) >. 'tl'" ~ C '"N °aJ :E Cd'~ .- 'tl'" ,.c:: ~ Z'.~ °aJ 0; = "; ,.c:: "t\l ~ö ~ ~ 'tl'" ....,... '"t\l > s'" '" ~ °aJ "t\l ""' t\l S ;g E ..... ~ CD ~ blJ ,.c:: S ... 0 ro'Qj > 00 I: .l:l 0;:: o~ Oo~ 0 '" ~ CD.1""4 " ~ ...... "-" > "t\l ... '" ...o~ ""'t\l 0 c/J..... I: r.n > I: ... t\l ""'.:: 0 ...... p, ...... CI.l Q,) Cl) ...... Q,) ...., ..." E Q, ;; o~ ~~ bIl ~E ~ ~ f~ o~'" t\l °ö'" -§ .:: oo.tJ~oj'''''''''' ... " Species " 0;:: ..0 '"t\l '"t\l S S ,.c:: e",p, '" ~ ~ ;e ö ~":5 t;: > > (Leguminosae) Lygos sphaerocarpa m m s ± + + + Medicago arborea m d ds + + + Medicago sativa t d ds + + + Ononis fruticosa m d ds ± + + + Ononis natrix m d ds + + + Ononis speciosa m d ds + + + Ononis tridentata m d s + + + Petteria ramentacea m d s + + + + Psoralea bituminosa m d ds + + Spartium junceum m n s + + + + Staurocanthus boivinii m d ds ± + + + Telline linifolia m n + + + Telline monspessulana m n s + + + Ulex europaeus t n ds + + + + Ulex minor m n ds ± + + + Ulex parvi{lorus m n ds ± + + + Linaceae Linum suffruticosum m d ds ± ± ± + + Linum tenuifolium m d ds ± ± ± + + Loranthaceae (Viscaceae) Loranthus europaeus m n ds** ± + + Viscum album t d ds** ± Viscum cruciatum m d ds** ± Malvaceae Lavatera arborea m n ds Lavatera maritima m d ds Lavatera oblongifolia m n ds + Lavatera olbia m n ds Moraceae Ficus carica m m t Ficus sycomorus m m t Morus alba m n t + + + + Morus nigra m n + + + + Myricaceae Myrica faya s n t + + + Myrica gaZe b m ds + ± + ±/- Myrtaceae Myrtus communis m d s + + + Oleaceae Fraxinus angustifolia m d + + Fraxinus excelsior t m + + Fraxinus omus m d + + Jasminum fruticans m d ds ± ± + + + Ligustrum vulgare n ± ± ± + +/-
Downloaded from Brill.com10/09/2021 04:50:05AM via free access IAWA Bulletin n,s" Vol. 8 (3),1987 255
(Table 1 continued) » rIJ ., "C ~ ... rIJ '03 o:I'~e- ~ "C 'Z':.:!; 'äi '03 ..<:: ~ rIJ "0:1 ., '; ~o ~ ~ "C ..<:: ... 13 rIJ rIJ ~ 0:1 .a '03 "0:1 "'"' ~ 13 ~ - bJ) "'"' ... 0 'e;; ~ ~ ~ ..<:: .!:l 0 __~ - ~ ~ Ul4,).~ I:: 'C" ., O'~ :E ...... "0:1 @ ...,~ "'"'0:1 0 rJJ'~ = CIl > j:! "'"'1:1 "0 .a ...... Po .!:l '3 ., ... ,i:l ., ,~ bII ~ ~ ~ ~ ca~ <> Species 0:1 '0'" ~-t ... Ul " Ul " il 0:1., 1:1 ~] ~] 'a:E ..c 0:1 0:1 13 13 ..<:: ~p. 'C > Cl) "'t:S c:J CIl~ t;:: > > (Oleaceae) Olea europaea m n t ± Phillyrea angustifolia m d s + + + Phillyrea latifolia m d s + + + Picconia azorica s n t + + + Syringa vulgaris d s ± ± + + + + Plantaginaceae Plantago arborescens s* d ds Plantago lagopus m d ds Plantago sempervirens m d ds Platanaceae Platanus hybrida t m t ± + Platanus orientalis m m t ± + Plumbaginaceae Limoniastrum articulatum m dh ds ± + Limonium bellidifolium m dh ds ±' + Limonium insigne m dh ds ± + Polygonaceae Polygon um equisetiforme m n ds + Polygon um maritimum m dh ds + Punicaceae Punica granatum m m s Ranunculaceae Clematis alpina t* n cl ± + + + Clematis campaniflora m n cl ± + + + Clematis cirrhosa m n cl ± + + + Clematis tzammula m n cl ± + + + Clematis vitalba n cl + + + + Clematis viticella m n cl + + + + Helleborus foetidus t d ds + + Thalictrum minus t n ds ± ± Resedaceae Reseda luteola n ds ± ± Reseda suffruticosa m d ds Rhamnaceae Frangula alnus m s ± ± + Frangula azorica s n t + Paliurus spina-cristi m d s Rhamnus alaternu.~ m n s ± + + Rhamnus alpinus t* n s ± + + + Rhamnus catharticus t d s ± ± + + Rhamnus glandulosa s n t + + Rhamnus lycioides m d ds + + + Rhamnus myrtifolius m d ds ± + + + Rhamnus pumilus m d ds ± + + +
Downloaded from Brill.com10/09/2021 04:50:05AM via free access 256 IAWA Bulletin n.s., Val. 8 (3),1987
CTable 1 continued) '"0'" & ~ .~ Ul 'S ~ Ul '"0 ,..c::: ~ Z;:: Q) Ol 'S <> Ul 0 Ul ~ ~ 'a o Ul Ul '"0'" ~ .~ b ~ -Q) Q) ~ ~ s ;g $ S» ~ Ul tllI ,..c::: ... 0 '00 Cd Q) b .~ Q) o·~ ..., '" I: <> ] o ~ > Q,) ...... td b <> .""...,~ ~ I: Ul > I: ... ä I: o ...... ::; ~'rn Q) Q) ...... Q.) -+;' Q) E o. Q);:1 ::; t; Ul ... ~.;d Q) bll ~ü '" ... <> ... <> .~ ~ '0 .~.~ Species ~~ Q) ~~ ..a ~ <> Q) I: >: '"~ '"~ S S ,..c::: Ulo. ';:::: > Q,l ;.aü ~05 f.C > > (Rhamnaceae) Rhamnus saxatilis t* d ds ± + + + Ziziphus jujuba m n t Rosaceae Alehemilla alpina t* n ds ± ± ± + Amelanehier ovalis t d s + ± + + Cotoneaster granatensis m* n s ± + ± + + Cotoneaster integerrimus t* d ds ± + ± + + Cotoneaster nebrodensis m* n s + + + Cotoneaster nummularia m* n s ± + + + + Crataegus calyeina m n s + ± + Crataegus laeiniata m n s + ± + Crataegus monogyna t n s + ± + Crataegus pyenoloba m n s + ± + Dryas octopetala t* d ds ± + + Malus domestica t d t ± + ± ± + Malus sylvestris t d t + ± ± + Mespilus germaniea t n t ± + ± + + Potentilla eauleseens t d ds + + Potentilla frutieosa b n ds ± + ± + Prunus armeniaea t n t + + + + Prunus avium t d t ± ± + + Prunus eerasus t d t ± + + + Prunus domestiea t n t + + Prunus duleis m m t ± + + + Prunus frutieosa t d t ± ± ± + + Prunus laurocerasus m m t + +/ Prunus lusitaniea m n s + +/ Prunus mahaleb t d t + + Prunus padus subsp. padus t m t ± ± + + Prunus padus subsp. borealis b* n t ± ± + + Prunus persiea t n t ± + + + Prunus prostrata m d ± ± ± + + Prunus ramburii m d s ± ± + + Prunus spinosa t d s + + Prunus webbii m m t + + + + Pyraeantha eoecinea m d s ± + + + Pyrus amygdaliformis m d t + + + Pyrus pyraster t d t + + + Rosa arvensis t n ± + ± + + Rosa eanina n s + + + + + Rosa glauca t n s ± + + + + Rosa sempervirens m n cl ± + + + Rosa spec. m n cl ± ± + + Rubus ehamaemorus b m ds +
Downloaded from Brill.com10/09/2021 04:50:05AM via free access IAWA Bulletin n.s., Vol. 8(3), 1987 257
(Table 1 continued) >. rIl ~ ~ rIl~ _ rIl '"'Ql :.0 !l'~ - '"'Ql ..c: .! ~~ Q) ~ rIl Q) 00 rIl ..c: ",., .... 'ca >. ..., > e rIl rIl - '"'Ql
Downloaded from Brill.com10/09/2021 04:50:05AM via free access 258 IAWA Bulletin n,s" Vol. 8 (3),1987
(Table 1 continued) 00 "Cl & i:' ,~'" 00 'Ql ol 00 "Cl ..<: 'öl 'Ql <> ~ ~~ Q) ~
Downloaded from Brill.com10/09/2021 04:50:05AM via free access IAWA Bulletin n.s., Vol. 8 (3),1987 259
(Table 1 continued) .0 ., ;-"i ., ." ~ .~ ., 'Ql
Materials and Methods Mediterranean: species from southern Europe The 505 species of native dicotyledonous and islands in the Mediterranean Sea subjected trees, shrubs, dwarf shrubs and climbers from to mild, often rainy winters, and hot, dry sum Europe, Cyprus (Asia minor) and Madeira (Ma mers. Species with a submediterranean distribu caronesia) described and pictured in Schwein tion were also included in this category. gruber (in preparation) were classified into Subtropical atlantic: species from Madeira, in broad ecological categories according to macro cluded in this study, mostly subjected to a humid climate, moisture avai!ability, and habit. F or climate, with mild winters and hot summers. each species single categories were chosen after Montane: a category recognised within the due consideration of the often wide ecological above, mainly latitudinally determined macro and habit ranges within them or of intermedi c1imatic zones of species growing at or above ate positions between two adjacent categories. the tim berline and thus subjected to much The following categories were recognised: lower temperatures and often quite different rainfall regimes than the lowland flora at the Macroclimatic zones (cf. Walther & Lieth, 1960) same latitude. The absolute altitude of the Boreal: species from northern Europe sub category 'montane' is much lower in the jected to very long, severe winters and short boreal zone than in the mediterranean region. cool summers. In this category species with a strictly boreal distribution were included as Moisture availability (arbitrary c1assification, weil as subboreal, and boreal to temperate spe depending not only on precipitation but also eies. on moisture retention capacity of the soi! Temperate: species subjected to relatively and vicinity to streams or lake shores) short winters of varying severity and warmer - Dry: species from physically dry habitats summers. In this category species with a strict (ranging from very dry to 'dry to normal ') Iy temperate distribution were combined with and halophytes which are subjected to a those with a sub boreal to temperate and a tem physiologically dry environment despite perate to submediterranean distribution. physical wetness.
Downloaded from Brill.com10/09/2021 04:50:05AM via free access 260 IAWA Bulletin n.s., Vol. 8 (3),1987
- Normal: species from habitats intermediate 33 138 301 33 62 between dry and mesic. 10Q% 1...... i_i .... J''-'._ •.• _d ...... _.i' •. !. 'u!ii - Mesic: species from wet, humid, or humid to normal habitats.
Habit - Trees: species comprising 'normal' trees, as weil as small trees to large shrubs. - Shrubs: multistemmed woody plants over 50 cm tall. 50% - Dwarf shrubs: shrubs commonly less than 50 cm tall (cxcept when growing in atypical, fa vourable conditions). - Climbers: climbing and scandent shrubs.
Wood anatomical characters were analysed from the descriptions and plates in Schwein vtt/t({(Y(({({{d/({(({4V({({{O/{{{{/1 grub er (in preparation) as weil as from the ex 0% _ •• ~... tensive microscopic slide collection at the Eid genössische Anstalt für das forstliche Versuchs wesen at Birmensdorf. Definitions of the wood MESIC anatomical parameters analysed are given in ~ NORMAL the results section. For full documentation of the species, their wood anatomy, and geo DRY graphical distribution the reader is referred to ~ Schweingruber (in preparation). A summary of Fig. I. Frequency distribution of species with the data analysed is presented in Table I. It a preference for mesic, 'normal', and dry sites should be emphasised that anatomical charac in the different macroclimatic zones. The mon ter states were qualitatively estimated, and that tane species are also included in the latitudinal no attempt was made to quantify features such zones. Total numbers of species indicated as '(almost) exclusively solitary vessels', 'semi above the columns. ring-porosity', etc., very precisely. Thus so me characters and species might be classified dif Common legend for Figures 1-12: ferently by other wood anatomists. However, Macroc1imatic zones: B = boreal; T = temperate; such differences would never result in other M = mediterranean; S = subtropical atlantic directions of the salient trends reported be (Madeira); Mont = montane. low. Moisture availability c\asses: D = dry; N = nor Ecological trends for each wood anatomical mal; M = mesic. character were analysed by calculating percen Habit categories: T = trees; S = shrubs; DS = tages of species possessing a certain character in dwarf shrubs; CL = climbers each ecological category.
Results Vessel perforations In the majority of species from Europe, Cy Relationships between ecological categories prus and Madeira the vessels have exclusively In Figures 1-3 the mutual relationships be simple perforations. The percentages of species tween macroclimate, moisture availability, and with exclusively scalariform and mixed simple habit categories is illustrated. Note that from and scalariform perforations in different ecol thc boreal to the mediterranean region the per ogical and habit categories is given in Figure 4. centage of mesophytes decreases, that dwarf There is a strong decrease in the proportion of shrubs constitute a very high proportion of the species with scalariform perforations going boreal, mediterranean and montane floras, and from boreal to Mediterranean, and from mesic that the tree habit is best represented in the to dry. Usually the montane flora shows a temperate region and in mesic sites. These ex higher incidence within a macroclimatic (lati pected relationships should be kept in mind tudinal) zone. In the subtropical flora of Ma when interpreting the various ecological trends deira (only 33 species studied) the percentage in the wood anatomy of trees, shrubs and clim of species with scalariform perforation plates is bers pictured in Figures 4-12. slightly higher than in the mediterranean re-
Downloaded from Brill.com10/09/2021 04:50:05AM via free access IAWA Bulletin n.s., Vol. 8 (3),1987 261
100% gion, in accordance with its more mesic c1imate. ,:·:Zf;:'{r[~T:;YJ.: ,: There is also a relationship with habit: tree spe ci es more often have scalariform perforations than shrubs and dwarf shrubs. The high percen tage of c1imbers with mixed simple and scalari form perforations is not very meaningful, be cause it is alm ost entirely due to the occur rence of very sporadic scalariform plates in the 50% genus Lonicera, wh ich is represented by a num ber of c1imbing species in our research mate rials. In Figure 5 it is shown that the latitudinal or macroclimatic trends and the mesic-xeric trend are unaffected or even slightly reinforced if only species of single habit categories (dwarf shrubs, trees) are plotted. However, dwarf shrubs show the ecological trends more strong Iy than trees.
Ring-porous tendencies climbers (24) The incidence of ring-porosity and semi-ring g dwarf -shrubs (225) porosity in different ecological categories is plotted in Figure 6. There is only a consistent shrubs (109) correlation with plant habit: ring-porosity de creases from tree, via shrub to dwarf shrub trees (117) habit, but is again very common in climbers. ~ Relationships with macroclimatic regions and Fig. 2. Frequency distribution of habit catego moisture availability are very weak or ambiguous. ries in the different macroc1imatic zones. The montane species are also inc1uded in the latitu Solitary vessels dinal zones. Total numbers of species indicated Percentages of species with (almost) exclu between brackets for the habit categories. See sively solitary vessels (i. e., over c. 80%) are also the common legend under Fig. I. plotted in Figure 7. There is a gradual decrease in occurrence of this feature going from boreal to mediterranean and subtropical, and from (250) (159) (96) trees to dwarf shrubs and climbers. There is no 100% apparent correlation with moisture availability. I:··WW/ff;~;:\·;;::;-::: climbers dwarf Different vessel size classes I shrubs The recognition of different vessel diameter shrubs classes in transverse section is somewhat arbi trary, and one could argue that each woody trees species shows this feature. In the present anal ~ ysis the qualification 'different vessel size c1as 50% ses' was only applied when relatively wide find narrow vessels are of common occurrence. All species with ring-porous tendencies (i.e., in c1uding semi-ring-porous woods) were also c1as sified as having different vessel size ciasses. In addition species with numerous very narrow vessels (usually intergrading with vascular tra cheids) in addition to 'narrow' or 'normal' ves 0% Vf///(]((/<.c
Downloaded from Brill.com10/09/2021 04:50:05AM via free access 262 IAWA Bulletin n.s., Vol. 8 (3),1987
100% MACROCLIMATE MOISTURE HABIT AV AILABIUIY
exclusively and/or mixed scalariform perforations in montane regions mixed simple & scalariform perforations 50% ~ exclusively scalariform perforations
0% 1«=< Fig. 4. Frequency distribution of species with scalariform perforations in different macroc1imatic, moisture availability, and habit categories. See also the common legend under Fig. 1. MACROCLIMATE MOISTURE 100% DWARF TREES DWARF TREES SHRUBS SHRUBS 50% 0% J,««<,",?? _ v< F ig. 5. Frequency distribution of species with scalariform perforations in different macroc1imatic and moisture availability categories plotted separately for dwarf shrubs and trees. See also the com mon legend under Fig. I. presentatives of numerous miscellaneous fami classes. No frequency distributions of differ lies show this syndrome. In a fairly high nu m ent vessel size c1asses for individual species ber of species ring-porous tendencies are co m were plotted, but usually all intermediates be bined with the occurrence of very narrow tween 'wide', 'normal', 'narrow' and 'very vessels (usually intergrading with vascular tra narrow' vessels are present; in species with very cheids) in addition to normallatewood vessels. distinct size c1asses in low frequencies, in oth These species thus show at least three vessel ers, e. g. in semi-ring-porous species, alm ost as size c1asses. In Plates land 2 some examples frequent as these size c1asses themselves. are given of species with different vessel size From Figure 8 it appears that in the Euro- Downloaded from Brill.com10/09/2021 04:50:05AM via free access IAWA Bulletin n.s., Vol. 8 (3),1987 263 =ring-porous andlor semi-ring-porous in montane regions = semi-ring-porous or semi-ring-porous to diffuse-porous 100% ~ = ring-porous MACROCUMATE MOISTURE HABIT AV AllABIillY 50% 0% . B Fig. 6. Frequency distribution of species with ring-porous tendencies in different macroc1imatic, moisture availability, and habit categories. See also the common legend under Fig. I. 100% r = in montane regions D =in entire flora sampies MACROCLIMATE MOISTURE HABIT A VAllABIillY 50% L----- '-1--- r------r--t-- 0% llibB T M S D N M T S DS CL Fig. 7. Frequency distribution of species with almost exc1usively solitary vessels (over c. 80% of all individual vessels) in different macroc1imatic, moisture availability, and habit categories. See also the common legend under Fig. I. pean flora as a whole, different vessel size c1as will be evident that the consistent trends ses are of very common occurrence, with peaks shown in Figure 8 must be largely due to the in the mediterranean, montane, dry, and dwarf fact that diffuse-porous species with extreme shrub categories. In the subtropical, mesic flora Iy narrow and 'normal' vessels are much more of Madeira different vessel size classes are, how common in the mediterranean, dry, and dwarf ever, of rare occurrence. If one considers that shrub categories than in the contrasting boreal, Figure 8 includes all species with ring-porous mesic, or tree categories. The peak for climbers, tendencies, and the latter do not show distinct on the other hand, is largely due to the higher macroclimatic or mesic-xeric trends (Fig. 6), it in ci den ce of ring-porosity in this habit category. Downloaded from Brill.com10/09/2021 04:50:05AM via free access 264 IAWA Bulletin n.s., Vol. 8 (3),1987 = in montane regions 100% = in emire flora sampies MACROCLIMATE MOISTURE HABIT D AVAllABILITY .-- .--- .--- r-- .--- f---I-- 50% 0% B T M S o N M T S DSCL Fig. 8. Frequency distribution of species with different vessel size classes in different macroclimatic, moisture availability, and habit categories. See also the common legend und er Fig. I. = in montane regions 100% I D = in emire flora sampies MACROCLIMATE MOISTURE HABIT AV AllABILITY r- 50% ~ rTl n, [I 0% B T M S 0 N M T S OS CL Fig. 9. Frequency distribution of species with spiral vessel wall thickenings in different macrocli matic, moisture availability, and habit categories. See also the common legend under Fig. 1. Spiral vessel wall thickenings with 19 of the 24 species showing spiral thick Figure 9 shows the incidence of spiral vessel enings on the vcssel walls. The percentages for wall thickenings in the different ecological ca trees, shrubs and dwarf shrubs are statistically tegories. They appear very common in the tem more meaningful since the numbers of species perate and mediterranean woody flora, and rela in these habit categories are much larger. tively rare in, the boreal, subtropical, and mesic species. The macroclimatic, and mesic-xeric Fibre-tracheids. vascular tracheids. and vasicen trends are, however, not very consistent. The tric tracheids incidence of spiral thickenings seems complete Fibre-tracheids, defincd according to Baas Iy independent of size in erect woody plants, (l986b) as fibres with distinctly bordered pits but climbers in the European flora show a peak (pit chamber c. 3 J.lm or more in diameter) and Downloaded from Brill.com10/09/2021 04:50:05AM via free access IAWA Bulletin n.s., Vol. 8 (3),1987 265 eommon in both radial and tangential walls, are xeric trends are mueh stronger (Fig. 11). How of mueh more frequent oeeurrenee in boreal ever, for trees the maeroclimatie trend breaks and montane temperate regions than in the down and the mesie-xerie trend is even reversed. mediterranean region or the subtropical flora Vaseular traeheids, here defined as traeheary of Madeira (Fig. 10). Their ineidenee inereases elements resembling in shape, size, wall pitting slightly from dry to mesie sites and is virtually and seulpturing very narrow vessel elements independent of habit in the overall flora sam (and almost invariably intergrading with the pIe of 505 speeies. If dwarf shrubs are analysed latter, cf. Plate Id) but lacking perforations or separately, the above maeroc1imatie and mesic- with only a single very small perforation, show 100% r MACROCLIMATE MOISTURE = in montane regions AV AILABILIFY D =in emire flora sampIes ----- ---- ~ 50% ~ ---- ~r-- r- r-- r-- - ~- ~ 0% B T M S D N M T S DS vL Fig. 10. Frequeney distribution of species with fibre-traeheids in different maeroc1imatic, moisture availability, and habit eategories. See also the common legend under Fig. I. MACROCLIMATE MOISTURE DWARF TREES DWARF TREEs 100% SHRUBS SHRUBS I-- ....- 50% r-- - f-- r- - r-- - - >-- 0% _. D T U nc:- D T .. e- r- .. .. _. - N M Fig. 11. Frequency distribution of speeies with fibre-tracheids in different macroclimatic and mois ture availability categories plotted separately for dwarf shrubs and trees. See also the common legend under Fig. I. Downloaded from Brill.com10/09/2021 04:50:05AM via free access 266 IAWA Bulletin n.s., Vol. 8 (3),1987 MACROCLIMATE MOISfURE HABIT AV AllABILITY = fibre- tracheids 100% ...... •:::; = vasicentric tracheids ~." = vascular tracheids 50% 0% I , , I I I I I I , B T M S 0 N M T S DSCL Fig. 12. Frequency distribution of species with vascular tracheids, vasicentric tracheids and fibre tracheids, in different macroclimatic, moisture availability, and habit categories. ---- = percentage of species with vascular tracheids in montane localities. See also the common legend under F ig. I. very clear ecological trends (Fig. 12). Their in pear to be very common throughout the cidence increases almost equally strongly in the woody flora of Europe, but they are most fre series boreal-temperate-mediterranean, mesic quent in the mediterranean, dry, and dwarf normal-dry, and trees-shrubs-dwarf shrubs. In shrub categories and least common in the sub montane regions they are relatively rare, as well tropical flora of Madeira. as in the subtropical flora sam pie from Madeira. In climbcrs their frequency equals that in erect Other wood anatomical characters shrubs. Although no quantitative features such as Vasicentric tracheids, here defined as strictly vessel diameter, vessel frequency, vessel mem imperforate, often irregularly shaped tracheids ber length, vessel wall thickness, fibre length adjoining wide or normal vessels as in Quercus, and fibre wall thickness were analysed in the are of very restricted occurrence in the Euro present study, some very general trends could pean flora (only Castanea, Quercus, Elaeagnus, be confirmed from a survey of the microscopic and Hedera) and show no meaningful ecologi slides, and the descriptions and illustrations in cal trends (Fig. 12); their relatively high inci the atlas: vessel diameter is very strongly re dence in species of tree habit is entirely due to duced and vessel frequency increased going the fact that all species of the Fagaceae and from trees to dwarf shrubs, while most clim Elaeagnus happen to be trees (or small trees to bers combine relatively high vessel frequencies shrubs) in the European flora. with wide diameters. The sm all vessel size and The cumulative incidence of fibre-tracheids, high vessel frequency in dwarf shrubs is typical vascular tracheids, and vasicentric tracheids is of both the boreal and mediterranean flora, but also plotted in Figure 12. Imperforate tracheary the boreal and high montane species generally elements with distinctly bordered pits thus ap- exceed the mediterranean ones in this respect. Plate I. Examples of secondary xylem with different vessel size classes in the European flora. - a. Clematis vita/ba (Ranunculaceae). Three size classes on account of ring-porosity and very narrow vessels associated with 'normal' latewood vessels. TS, x 40. - b. Lycium europaeum (Solanaceae). Three vessel size classes on account of ring-porosity and very narrow vessels, intergrading with vascular tracheids in flame-like to dendritic pattern with 'normal' vessels in intermediate wood and latewood. TS, x 40. - c & d. Erinacea anthyllis (Leguminosae). Three vessel size classes. Normal latewood vessels associated with very narrow vessels intergrading with vascular tracheids (arrows). TS, x 160; RLS, x 400. Downloaded from Brill.com10/09/2021 04:50:05AM via free access 267 via free access Downloaded from Brill.com10/09/2021 04:50:05AM c- 00 0\ (3),1987 (3),1987 8 Val. n.s., Bulletin Bulletin IAWA IAWA via free access (3),1987 (3),1987 8 Vol. n.s., Bulletin Bulletin Downloaded from Brill.com10/09/2021 04:50:05AM IAWA IAWA 00 \0 N 268 IAWA Bulletin n.s., Vol. 8 (3),1987 269 Some unusual qualitative features such as in vatera (Malvaceae) and Daphne (Thymelaea cluded phloem and raylessness are restricted to ceae). On the other hand, Arctostaphylos (Eri very few families, all with a largely mediterra caceae) follows the general trend because the nean distribution in Europe. In view of the boreal to temperate A. alpina lacks spirals, limitation of these eharaeters to few taxonomie while the drier A. uva-ursi shows them. Like groups no signifieance ean be attached to the wise, in Teucrium (Labiatae), the subtropical resulting ecological trend. T. betonicum is the only species lacking spirals, Parenehyma abundance has not been anal while the mediterranean to temperate species ysed quantitatively, but it seems that in medi all have them. Within other genera or families terranean species parenchyma is somewhat ecological trends in wood anatomy would more often paratracheal and abundant than in probably only become apparent if subtropical temperate and boreal species. to tropical relatives were included, e.g. of Ilex Septate fibres are of rare occurrence in the (Aquifoliaceae) and Prunus (Rosaceae), most European flora as a whole, and have only been tropical species of which lack spiral thickenings recorded in 4% of the species. This is very whereas almost all North or South temperate much lower than the value of 22% for world species have them (cf. Baas, 1973). woods given by Wheeler et al. (1986), support F or vascular tracheids and ring-porous ten ing the impression that septate fibres are large deneies the ecological trends are partly repeat ly restricted to tropical families (Metcalfe & ed within so me fami!ies: usually Boraginaceae, Chalk, 1950). Compositae, Celastraceae, and Rhamnaceae from Madeira lack vascular tracheids and ring porosity, while the mediterranean or temperate Ecological trends within families mainland relatives have one or both of these at Despite the very distinct ecological trends in tributes. However, there are also many cases in so me of the wood anatomical characters emerg which no ecological trend is apparent for these ing from the floristic analysis, summarised in characters within widely distributed families or Figures 4~ 12, hardly any trace of them can be genera (Table I). Also there are ecologically found within single families or genera with a diverse groups such as the woody Papilionoi wide ecologieal range and represented by sever deae (Leguminosae), for which vascular tra al to quite numerous speeies in oUf research cheids are a constant feature in the flora of materials (cf. Table I). For instanee, type of Europe. One would have to extend the compar perforation plate varies in so me families (e. g., ison to the tropical genera of this large subfa Caprifoliaceae, Corylaeeae, and Ericaceae) but mily to find an ecological relationship, parallel is often eonstant for individual genera irrespec to the one found on a floristic basis in Europe, tive of the ecology of their species. Only in because tropical rainforest Papilionoideae lack Ericaceae there is a vague tendeney for species vascular tracheids and different vessel size clas with exclusively simple perforations to be con ses. fined to dry, mediterranean sites, while species In quantitative characters such as vessel diam with mixed simple and scalariform plates are eter and frequency, and especially in vessel coneentrated in temperate to boreal and nor member length, ecological trends within genera mal to mesic sites. Exeeptions occur, however. and families might be stronger, as suggested by In Carpinus (Corylaceae) the general trend is numerous monographie wood anatomieal stu even reversed, and C. orientalis, which is ex dies (e.g. Carlquist, 1966 and many subsequent posed to drier eonditions than C. betulus, papers; Baas, 1973; Van der Graaff & Baas, shows occasional scalariform perforations, 1974; Van den Oever et al., 1981; Rury, 1985). while C. betulus has exclusively simple perfora However, an analysis along these lines for the tions. Spiral thickenings seem to vary without woody flora of Israel and adjaeent regions any ecological pattern in genera such as Helian showed very !ittle trace of the general floristic themum (Cistaceae), Corylus (Corylaceae), La- trends (Fahn et al., 1986). Plate 2. Examples of secondary xylem with different vessel size classes in the European flora. ~ e & f. Cneorum tricoccon (Cneoraceae). Two to three vessel size classes on account of semi-ring porosity and narrow to very narrow vessels intergrading with vascular tracheids in a flame-!ike pat tern. IS, x 40; RLS, x 250. ~ g. Arenaria serpyllifolia (Caryophyllaceae). Diffuse-porous secondary xylem with two vessel size classes: very narrow vessels (arrows) interspersed between normal vessels. TS, x 160. ~ h. Arctostaphylos uva-ursi (Ericaceae). Semi-ring-porous to diffuse-porous wood with two intergrading vessel size classes. TS, x 40. Downloaded from Brill.com10/09/2021 04:50:05AM via free access 270 IAWA Bulletin n.s., Vol. 8 (3),1987 Extrapolation tor the entire woody flora o[ by the fact that only very few genera with a Europe high number of species are underrepresented. Although the trends reported above are based For characters which are more or less constant on an exceptionally high number of species, a at the family level, such as fibre-tracheids in roughly equal or slightly higher number of Cistaceae and most European Ericaceae and woody species native to Europe has not been Rosaceae, solitary vessels in Cistaceae, different ineluded in this survey. This was partly for lack vessel size elasses and vascular tracheids in most of material, partly because it was considered European Labiatae and Leguminosae, the da ta unproductive to collect, section and describe from Table 2 could be used to calculate cor the anatomy of all woody species belonging to rected values for the European flora as a whole. large, mostly uniform genera such as Cistus, On the other hand it would be too speculative Rosa, Rubus, Salix, Thymus, etc. In the species to extrapolate for certain characters in variable missing from the European mainland sampie families, such as scalariform perforations in there is a bias towards mediterranean dwarf Ericaceae, solitary vessels in Rosaceae, spiral shrubs and normal shrubs. Coverage of tree thickenings and ring-porosity in most families species is elose to 100%, and coverage of alpine listed, etc. We have therefore refrained from and boreal regions which are poorer in woody caJculating any extrapolated percentages for representatives is also relatively high. This the entire European flora, because this would means that the overall floristic trends pictured give a misleading impression of accuracy about in Figures 1-12 would undergo so me quanti characters and species of which we simply do tative changes, if all species had been ineluded. not yet know enough. We are, however, convinced that these changes would not have altered the direction of any Discussion ecological trend. Only those characters which occur preferentially in mediterranean shrubs Comparison with other studies and dwarf shrubs would show increased per Many of the results reported above agree centage values in the entire European flora remarkably weil with ecological trends in wood sampie. anatomy postulated on smaller research sam Most small families in our research material pies, and thus reinforce their general validity. are represented by 70 to 100% of their species. The scarcity of scalariform perforations in Of the larger families with more than 20 spe warm and dry habitats has been reported often cies in the European woody flora according to before (Baas, 1976, 1982, 1986a; Carlquist, Tutin et al. (1964-1976) the percentages may 1975). The absolute percentage values for be much lower, as roughly indicated in Table Europe reported here (8 % with exclusively sca 2. Exceptionally low percentages in Cistaceae, lariform plates and 6% with mixed simple and Labiatae, Rosaceae, and Salicaceae are caused scalariform ones) are lower than those calcu lated on a generic basis from Greguss' wood anatomical survey (1959) of ISS genera (16% and 8%, respectively; Baas, 1976). This can be Table 2. Approximate percentages of woody accounted for by the inelusion of a much great species covered in the anatomical survey and er number of dwarf shrubs from specialised fa belonging tot the larger families. Estimated to mi lies such as Chenopodiaceae, Compositae, tal number of woody species native in Europe Labiatae, Leguminosae, etc., in the present re between brackets (taken from Tu tin et al., search materials from mediterranean sites, 1964-1976). which always lack this primitive type of vessel perforation, and by the differences caused by Percentage Total taking the number of species as a basis, instead of the number of genera. Many genera with Boraginaceae 40 (20) simple perforations were represented by more Chenopodiaceae 70 (20) species than the genera with scalariform per Cistaceae 20 (70) forations in our research sampie. Wheeler et al. Compositae 50 (50) (1986) give a percentage of 17% of over 5000 Ericaceae 60 (45) world woods with scalariform perforations Fagaceae 70 (25) (i.e., species with exelusively scalariform plates Labiatae 30 (120) plus species with mixed simple and scalariform Leguminosae 35 (200) plates). This percentage is also relatively high Rosaceae 25 (230) and would be much lower if shrubs and dwarf Salicaceae 20 (80) shrubs as weil as tropical woods would be Thymelaeaceae 35 (33) equally weil represented in their database as Downloaded from Brill.com10/09/2021 04:50:05AM via free access IAWA Bulletin n.s., Vol. 8 (3),1987 271 the temperate trees (cf. Baas, 1976 for world sites in general (Fig. 4) can be interpreted as an wide trends in the incidence of scalariform ves adaptation to greater conductivity (or reduced sei perforations). resistence to flow) in conditions with at least The ecological trends for species with two periodically high transpiration rates. Their low vessel size classes and/or vascular tracheids are occurrence in dwarf shrubs can also be account similar to those reported by Baas et al. (1983), ed for by the predominance of this growth Baas and Carlquist (1985), Carlquist (1985a), form in dry, mediterranean sites, reinforced by Carlquist and Hoekman (1985), and Fahn et al. the fact that many families with dwarf shrubs (1986) for the floras of Israel and southern (often largely herbaceous phylads) are evolu California (note that Carlquist's definition of tionary highly advanced and lack scalariform vasicentric tracheids includes most of the vas perforations throughout their geographical and cular tracheids reported in this study). ecological ranges (Chenopodiaceae, Labiatae, Spiral thickenings have been shown to be Leguminosae, etc.). The high incidence of sca far more common in temperate than in tropical lariform perforations in frost-prone boreal and regions (Kanehira, 1921; Baas, 1973, 1986a), subalpine habitats can also be interpreted as a but their relationship with drought remains functional advantage for the trapping and loca somewhat ambiguous, as also borne out in this lisation of embolisms which must be abundant study of European woods (cf. Baas & Carlquist, when damp bubbles form in thawing xylem sap 1985). The generally high incidence of spiral (Zimmermann, 1978, 1983). The low incidence thickenings throughout the European flora of scalariform perforations (as the only type) is (53% of all species) becomes apparent if it is in agreement with the general view that the ac compared with the values of 5~ 15% in various quisition of the climbing habit has accelerated tropical floras (Baas, 1986a) or 11 % for a large the elimination of scalariform perforations to sampie of world woods (Wheeler et al., 1986). increase hydraulic conductance (cf. Zimmer Fibre-tracheids (as defined here comprising mann & Brown, 1971; Carlquist, 1975). The ru 'true' tracheids, sensu Carlquist, 1985b) appear dimentary presence of scalariform perforations to follow altitudinal and latitudinal trends in in climbing Lonicera species should be viewed the European woody flora postulated before on against the background of common occurrence the basis of smaller sampies (Baas, 1982, 1986a; of exclusively scalariform perforations in erect Carlquist & Hoekman, 1985). Caprifoliaceae (Metcalfe & Chalk, 1950). Trends in other characters reported in this Ring-porosity and presence of different ves paper are not readily comparable with data in seI size c1asscs in general (Figs. 6 & 8) are of the literature. The percentage of species with importance for the combined efficiency (wide solitary vessels in the European flora as a whole vessels) and safety (narrow vessels in high num (25%), agrees closely with the value for the bers) of xylem sap transport at different times mediterranean component of the flora of Israel in or throughout the growing season. Wide ear (Fahn et al. , 1986), but our data do not allow Iywood vessels are pro ne to embolism at times a comparison with data on vessel grouping in of water stress, which probably irreversibly in the floras of southern California and Israel (cf. capacitates them for sap transport. Narrow ves Baas & Carlquist, 1985). sels can then take over sap conduction, albeit at a very much reduced rate due to high resis Evolution and [unctional signi[icance tance to flow (Ellmore & Ewers, 1985). AI Any functionally adaptive interpretation of though the ecological trends for ring-porous the trends reported here should take into ac tendencies are not very clear in the European count the general evolutionary trends in wood flora, the combination with other means for anatomy as established by Bailey and Tupper creating different vessel size classes (Fig. 8) (1918) and expanded and confirmed in many shows that especially mediterranean and/or later studies (for reviews, see Carlquist, 1975, xeric species have opted for this dual strategy and Baas, 1982, 1986a). Thus when noticing a guaranteeing a relatively efficient as weil as safe very high incidence of primitive features such hydraulic system. as fibre-tracheids, solitary vessels, or scalari Vascular tracheids (Fig.12), which almost form perforations in cool and/or mesic vegeta invariably intergrade with very narrow vessels, tion types, one should ask the question why also show a distinct trend to increase their these characters were preferentially eliminated abundance in dry, hot areas. Here only safety (i. e., selected against) in warmer and drier habi of the hydraulic system can be invoked as a tats, rather than search rigidly for their adap function, and makes sense if one considers the tive significance in boreal and montane regions. likely high magnitude of negative press ures The low incidence of scalariform perfora during the hot dry summers in the mediterra tions in the mediterranean region and in dry nean region. Downloaded from Brill.com10/09/2021 04:50:05AM via free access 272 IAWA Bulletin n.s., Vol. 8 (3),1987 Fibre-tracheids, a primitive feature, probably ence of fibre-tracheids: 67% of the species with also provide an extremely safe, but highly inef fibre-tracheids have (almost) exclusively soli ficient subsidiary conductive system if the bor tary vessels. The latter correlation has also been dered pits are large and numerous enough (cf. established by Carlquist (1984) between pres Braun, 1970). Yet they follow an ecological ence of 'true tracheids' and exclusively solitary trend entirely opposite to the one for vascular vessels, but in a more absolute way. In his opi tracheids (Fig. 10): they are most abundant in ni on this correlation has a functional signifi mesic, cool regions. Here one has to consider cance because the subsidiary conductive system the close phylogenetic link between scalariform of ground tissue tracheids (termed fibre-tra perforations and fibre-tracheids (cf. Bailey & cheids by us, cf. Baas, 1986b) would make ves Tupper, 1918; Metcalfe & Chalk, 1950). In the sel-grouping (a hypothetical alternative device European flora this link becomes obvious of for hydraulic safety) redundant. one considers that for the flora sam pie as a Spiral thickenings have been the subject of whole 36% of the species show fibre-tracheids, various functional interpretations, none of but that in woods with scalariform perforations which is satisfactory in our opinion. Their pre 71 % of the species have this type of ground tis dominance in temperate and mediterranean sue fibres. The more or less parallel ecological zones, here again confirmed for a larger flora trends for scalariform perforations and fibre sampie than ever analysed before, remains tracheids can thus be interpreted as the result puzzling. If they serve to reduce the risks of of evolutionary constraints, where the elimina embolisms by offering more bonding surface tion of scalariform perforations in warm and between the vessel wall and the water column dry regions was more important than the reten as suggested by Carlquist (1982) it is difficult tion of fibre-tracheids. However, the mesic to understand why they are not more clearly xeric trends for fibre-tracheids are less clear related to moisture availability. In desert re than those for scalariform perforations (Figs. 4, gions of the Middle East and southern Cali 10 & 11), perhaps indicating that at least in fornia their incidence is lower than in the trees the retention of fibre-tracheids in dry mediterranean maquis or chaparral in these habitats had some advantage for safety of the countries or in Europe. In the absence of any hydraulic system. However, this hypothesis experimental evidence their function simply stretches the limits of permissible and meaning remains elusive at this stage of our knowledge. ful speculation. If all possibilities for extreme safety, viz. Conclusions fibre-tracheids, and vasicentric and vascular tra Most qualitative wood anatomical features cheids, are considered together it becomes ap analysed in the large flora sampie from Europe, parent how great a proportion of species in the Cyprus, and Madeira show distinct or weak European flora have a provision for safety in ecological trends, which can be partly under their hydraulic architecture (Fig. 12). The added stood as the result of functional adaptations in percentages given in Figure 12 (up to 99% for the evolution of woody phylads, to comply with dry regions) should be lowered slightly, because dernands for hydraulic fitness (safety Imd/or a few taxa (e.g. species of Elaeagnus, Pteroce efficiency in varying emphasis) in different en phalus, Globularia) have two of the added char vironments. Partly the trends seem to be the acters simultaneously. The quite high values for result of correlative constraints imposed by the species with aboreal, temperate and / or mesic limited possibilities of xylem specialisation. De ecology (58-78%) may be of functional signi spite significant trends in the flora as a whole, ficance as weil, because even in these categories most of these trends are not clearly apparent water stress may occur at irregular intervals. within ecologically diverse families or genera The ecological trends for (almost) exclusive within Europe. This suggests that the trends in Iy solitary vessels are rather ambiguous (Fig. 7) the present day flora are largely the result of since the correlation with macroclimate is not selection of previously evolved types and not reflected in a relationship with moisture avail of adaptive changes concurrent with more re ability. However, solitary vessels are again a cent speciation events. primitive feature (Metcalfe & Chalk, 1950), The limitations of the present analysis should preferentially associated with scalariform per also be stressed here. Information on microsite, forations (57% of the species with exclusively microclimate, functional leaf anatomy, extent scalariform perforations have mostly solitary of the root system, and phenology should vessels; 37% of the species with mixed simple ideally be incorporated but was not available and scalariform plates, and 23% of the entire for most of the species. Inclusion of such infor flora sampie). There is an even stronger mutual mation might, however, have lead to a better correlation between solitary vessels and pres- understanding of the wood anatomical varia- Downloaded from Brill.com10/09/2021 04:50:05AM via free access IAWA Bulletin n.s., Vol. 8 (3),1987 273 ti on within genera and families. Moreover, one - 1982. Systematic, phylogenetic, and ecol must be aware that the existence of general ogical wood anatomy. History and perspec trends, expressed in percentages of species with tives. In: New perspectives in wood anato certain attributes in certain habitats, implies my (ed. P. Baas): 23-58. NijhoffjJunk, that still a proportion of the species (often a The Hague. large one) does not obey the trend. In other - 1986a. Ecological patterns in xylem anato words, each single biotope sustaining several my. In: On the economy of plant form and woody species belonging to different genera, function (ed. T.J. Givnish): 327-352. Cam will also harbour wood structural diversity, and bridge University Press, Cambridge, New many combinations of wood anatomical fea York. tures are apparently successful to fulfil the - 1986b. Terminology of imperforate trache functional demands which woody tissues have ary elements. In defence of libriform fibres to meet in any type of habitat. with minutely bordered pits. IA WA Bull. Nevertheless the correlation of wood anato n. s. 7: 82-86. my with macro-ecological factors is impre~sive, - & S. Carlquist. 1985. A comparison of the and provides additional evidence for a prefer ecological wood anatomy of the floras of ential selection of advanced xylem features in southern California and Israel. IA WA Bull. dry, warm regions and in the more mesic atlan n.s. 6: 349-353. tic flora of Madeira, also subjected to high te m - , E. Werk er & A. Fahn. 1983. Some ecolog peratures. It is likely that the same environ ical trends in vessel characters. IA WA Bull. mental factors were instrumental in the past to n.s.4: 141-159. accelerate xylem specialisation such as loss of Bailey, LW. & W.W. Tupper. 1918. Size varia scalariform perforations and the parallel devel tion in tracheary cells. L A comparison be opment of vascular tracheids in many groups. tween the secondary xylems of vascular Cool regions have served as a refugium for cryptogams, gymnosperms and angiosperrns. primitive wood anatomical features such as sca Proc. Amer. Arts Sci. 54: 149-204. lariform perforations, and solitary vessels in Braun, H.J. 1970. Funktionelle Histologie der combination with fibre-tracheids. sekundären Sprossachse. L Das Holz. Ency In the literature the impression is sometimes clopedia of Plant Anatomy IX (I). Born created that macroclimatic trends (largely corre traeger, Berlin. lated with la titude and altitude of provenance) Carlquist, S. 1966. Wood anatomy of Composi in wood anatomy conflict with trends based on tae: a summary, with comments on factors the mesic or xeric preference of species, or at controlling wood evolution. Aliso 6: 25- least are less reliable. The present analysis of 44. qualitative wood anatomical characters clearly - 1975. Ecological strategies of xylem evolu shows the complementary nature of macro tion. Univ. California Press, Berkeley. climate and moisture availability in governing - 1977. Ecological factors in wood evolution, general ecological trends: for some features ma a floristic approach. Amer. J. Bot. 64: croclimatic trends are stronger than mesic-xeric 887-896. trends, for others the latter are equally strong. - 1982. Wood anatomy of Illicium (Illicia ceae): Phylogenetic, ecological, and func Acknowledgements tional interpretations. Amer. J. Bot. 69: The first author gratefully acknowledges 1587-1598. financial support from the Eidgenössische An - 1984. Vessel grouping in dicotyledon wood: stalt für das forstliche Versuchswesen at Bir significance and relationship to imperforate mensdorf to work on this project in Switzer tracheary elements. Aliso 10: 505-525. land. Mr. Joop Wessendorp (Leiden) kindly - 1985a. Vasicentric tracheids as a drought prepared the diagrams. survival mechanism in the woody flora of southern California and similar regions; re References view of vasicentric tracheids. Aliso 11: 37- Baas, P. 1973. The wood anatomy of Ilex 68. (Aquifoliaceae) and its ecological and phy - 1985b. Observations on functional wood logenetic significance. Blumea 21: 193-258. histology of vines and lianas: vessel dimor - 1976. Some functional and adaptive as phism, tracheids, vasicentric tracheids, nar pects of vessel member morphology. In: row vessels, and parenchyma. Aliso 11: Wood structure in biological and technolog 139-157. ical research (eds. P. Baas, A.J. Bolton & - & D.A. Hoekman. 1985. Ecological wood D.M. Catling): 157-181. Leiden Bot. Series anatomy of the woody southern Californian 3. Leiden Univ. Press. flora. IAWA Bull. n.s. 6: 319-347. Downloaded from Brill.com10/09/2021 04:50:05AM via free access 274 IAWA Bulletin n.s., Vol. 8 (3),1987 Ellmore, G.S. & F.W. Ewers. 1985. Hydraulic Schweingruber, F.H. In preparation. Holzana conductivity in trunk xylem of elm, Ulmus tomie europäischer Bäume und Sträucher. americana. IAWA Bull. n.s. 6: 303-307. Tutin, T., V.H. Heywood, N.A. Burgess, D.H. Fahn, A., E. Werker& P. Baas. 1986. Wood anat Valentine, S. M. Walters, D.A. Webb (eds.). omy and identification of trees and shrubs 1964-1976. Flora Europaea 1-4. from Israel and adjacent regions. The Israel Walther, H. & H. Lieth. 1960. Klimadiagramm Acad. of Sciences and Humanities. J erusa Weltatlas. Fischer, Jena. lern. Wheeler, E.A., R.G. Pearson, C.A. Lapasha, T. Graaff, N.A. van der & P. Baas. 1974. Wood Zack & W. Hatley. 1986. Computer-aided anatomical variation in relation to latitude wood identification. North Carolina Agric. and altitude. Blumea 22: 101-121. Res. Servo Bull. 474. Raleigh, North Caro Greguss, P. 1959. Holzanatomie der europäi• lina. schen Laubhölzer und Sträucher. Akademiai Zimmermann, M. H. 1978. Structural require Kiado, Budapest. ments for optimal water conduction in tree Kanehira, R. 1921. Anatomical characters and sterns. In: Tropical trees as living systems identification of Formosan woods, with cri (eds. P.B. Tomlinson & M.H. Zimmermann): tical remarks from the climatic point of 517-532. Cambridge Univ. Press, Cam view. Bur. Productive Indust., Taihoku. bridge, New Y ork. M.etcalfe, C. R. & L. Chalk. 1950. Anatomy of - 1983. Xylem structure and theascent of the Dicotyledons. Clarendon Press, Oxford. sap. Springer series in Wood Science I. Oever, L. van den, P. Baas & M. Zandee. 1981. Springer, Berlin, New York, Heidelberg, Comparative wood anatomy of Symplocos Tokyo. and latitude and altitude of provenance. - & C. L. Brown. 1971. Trees. Structure and IAWA Bull. n.s. 2: 3-24. function. Springer, Berlin, New York, Hei Rury, P.M. 1985. Systematic and ecological delberg, Tokyo. wood anatomy of the Erythroxylaceae. IAWA Bull. n.s. 2: 3-24. Downloaded from Brill.com10/09/2021 04:50:05AM via free access