IAWA Journal, Vol. 19 (1),1998: 43-97 SYSTEMATIC WOOD ANATOMY OF CORNACEAE AND ALLIES by S. Noshiro l & P. Baas2 SUMMARY The wood anatomy of Comaceae, Alangiaceae, Garryaceae, and Nyssa­ ceae constituting the Comales in the sense of Cronquist (1981, 1988) is described in great detail and subjected to a cladistic analysis. A micro­ scopic identification key to the woods studied is given. The alliance in­ cludes seventeen genera, mostly of trees and shrubs, very rarely herbs. Although wood anatomically fairly homogeneous, variation exists in both qualitative and quantitative characters. Some of the latter show distinct latitudinal trends within individual genera, and character states have only been recognised taking their latitudinal dependencies into ac­ count. The character states ultimately recognised in these continuously varying quantitative characters coincide with intergeneric or intersec­ tional gaps. The cladistic analysis based on a datamatrix with twenty­ one characters (Table 3) and using Cereidiphyllum, Daphniphyllum, and Hamamelis as outgroups yielded a strict consensus tree with a quadrichotomy with two monophyletic clades, Hydrangea panieulata (a representative of the closely allied Hydrangeaceae) and Daph­ niphyllum (Fig. 81). One weakly supported clade includes Alangium, Camptotheea, Cornus, Curtisia, Davidia, Diplopanax, Mastixia, and Nyssa without any robust lineages among them. The other genera, Ara­ lidium, Aueuba, Corokia, Garrya, Griselinia, Helwingia, Melanophylla and Toricellia, constitute a second, well-supported clade. Two Hydran­ gea taxa included in the analysis nest in the second clade and a basal branching respectively. The wood anatomical diversity pattern thus supports a family concept of Comaceae including Cornus, Curtisia, Diplopanax, Mastixia, Alangiaceae, and Nyssaceae, and exclusion of the genera in the other clade. There is remarkable agreement between some of these wood anatomical r~sults and recent cladistic analyses of rbeL sequences by Xiang and co-workers. The infrageneric classifica­ tion of Cornus, Alangium and Nyssa is also discussed. Key words: Comaceae, Alangiaceae, Garryaceae, Nyssaceae, Hydran­ gea, wood anatomy, latitudinal trends, cladistic analysis. 1) Forestry and Forestry Products Research Institute, Tsukuba Norin, P.O. Box 16, Ibaraki 305, Japan. 2) Rijksherbarium/Hortus Botanicus, P. O. Box 9514, 2300 RA Leiden, The Netherlands. Downloaded from Brill.com10/06/2021 07:51:56AM via free access Table 1. Systematic treatment of the Comaceae alliance. 1:1: Cronquist Harms Wangerin Me1chior Hutchinson Takhtajan Eyde Thorne 1982 1898 1910 1967 1967 1997 1988 1992 Cornales Cornaceae Cornaceae U mbelliflorae Araliales Comales Cornaceae Cornales Comaceae Aralidium (Araliaceae) Araliaceae (Aralidiales) Aralidiaceae Aucuba * * * * (Aucubales) Aucubaceae Cornus * * * * * * * Corokia * * * * (Hydrangeales) (Hydrangeales) Curtisia * * * * Curtisiaceae Curtisiaceae Griselinia * * * * (Griseliniales) (H ydrangeales) Helwingia * * * Araliaceae (Helwingales) (Araliales ) Kaliphora * * * (Hydrangeales) (Hydrangeales) Mastixia * * * * Mastixiaceae * * Melanophylla * * * * (Hydrangeales) (Hydrangeales) Toricellia * * * * (Toricelliales) (Araliales) (Diplopanax) Araliaceae Mastixiaceae *1) * Nyssaceae Nyssa * Nyssaceae Nyssaceae Nyssaceae Nyssaceae * * Camptotheca * Nyssaceae Nyssaceae Nyssaceae Nyssaceae * * Davidia * Nyssaceae Davidiaceae Nyssaceae Davidiaceae * * Garryaceae ...... Downloaded fromBrill.com10/06/2021 07:51:56AM Garrya * Garryaceae Garryaceae Garryaceae (Garryales) Garryaceae Alangiaceae ;J>~ '-< Alangium * Alangiaceae Alangiaceae Alangiaceae Alangiaceae Alangiaceae 0 Araliaceae Araliaceae Vitaceae at= Umbelliferae Caprifoliaceae Gunneraceae f-. Haloragaceae Eucommiaceae ~ ...... Icacinaceae \D Cardiopteridaceae -----...... -------_... _-- '-' ...... * = inclusion in Cornaceae, () = exclusion from Cornaceae or Cornales. \D via freeaccess \D 1) Eyde & Xiang 1991. 00 Noshiro & Baas - Systematic wood anatomy of Comaceae 45 INTRODUCTION Comaceae and allies constitute a group oftrees and shrubs (very rarely herbs) which has its main distribution in the northem hemisphere. The circumscription of this alli­ ance has been in constant dispute and varies greatly between systematists (Table 1; cf. also Xiang et al. 1993). Harms (1898) recognised 15 genera in seven subfamilies in his treatment of Comaceae. Wangerin (1910) divided Comaceae into four separate farnilies, Comaceae, Nyssaceae, Alangiaceae, and Garryaceae. In more recent years Cronquist (1981) adopted the family circumscription of Harms (1898) in his Comales and regarded the four families ofWangerin (1910) to constitute the order. Cronquist (1988) later included Nyssaceae in Comaceae following the opinions of Eyde (1988). Hutchinson (1967) included Comaceae, Alangiaceae, Garryaceae, and Nyssaceae to­ gether with Araliaceae and Caprifoliaceae in his Araliales, and Melchior (1964) in­ cluded the four families with Araliaceae and Umbelliferae in his series Umbelliflorae. Dahlgren (1980) and Thome (1992) have the broadest concept of the Comales. Dahlgren included 22 families in his Comales besides the above four families whose constituent genera he placed in eight families. Thome (1992) included four suborders in his Comales, nine families in Comineae, and Davidia, Camptotheea, Nyssa, Di­ plopanax, Mastixia, and Cornus in Comaceae. In contrast, others adopted a much nar­ rower circumscription for Comales or Comaceae. Takhtajan (1997) included only eight genera in his Comales and placed the other nine genera in seven separate orders. He adopted narrower family circumscriptions and established eight families among the nine genera of Comales. Eyde (1988) limited his Comaceae to only six genera, including the latest addition of Diplopanax formerly placed in Araliaceae (Eyde & Xiang 1990). He was not sure of the affinity of Alangium with the Comales, but con­ sidered the other genera to be remotely related. In recent years rbeL sequences of the Comaceae alliance have been analysed (Xiang et al. 1993 and Xiang & Soltis in press) based on the circumscription of the Comales by Cronquist (1981) with the addition of Diplopanax. These results showed a Coma­ ceous clade that included only some genera; the other genera were scattered among several other clades. The Comaceous clade is quite close to the Hydrangeaceae. To obtain results comparable to those of the rbeL sequences, we studied all the genera of Cronquist's Comales, and selected three outgroup genera from the taxa used for the rbeL analyses. The Comales in this study consist of Alangiaceae, Comaceae, Garryaceae, and Nyssaceae (Cronquist 1981). Diplopanax is provisionally included in the Comaceae following Eyde & Xiang (1990). The infrageneric subdivision of the studied genera and species circumscription follows Bloembergen (1939) for Alangium with revi­ sions of nomenclature by Eyde (1968), Murrell (1993) for Cornus, Matthew (1976) for Mastixia, and Dahling (1978) for Garrya. Besides these revisions, we follow Fang (1983) for Chinese Alangium, Ricket (1945) for North American Cornus, Soong (1990) for Chinese Mastixia, Aueuba, and Helwingia, Hu (1990) for Cornus s.l. and Torieellia, Burckhalter (1992) for North American Nyssa, Fang (1983) for Asian Nyssa, and Dudley & Santamour (1994) for Cornus angustata. Downloaded from Brill.com10/06/2021 07:51:56AM via free access 46 IAWA Journal, Vol. 19 (1), 1998 The genus Cornus has been regarded as a single genus in the broad sense or has been subdivided into several genera, and there is as yet no consensus (Murrell1993). In this study we employed the broad genus concept following Eyde (1987). This finds at least some support in the rather uniform wood structure within Cornus S.l. The systematic position of Alangium grisolleoides within Alangiaceae is in dis­ pute. Eyde (1968) included it in sect. Constigma mainly based on fruit structure, but later he doubted his former decision because pollen morphology and wood anatomy suggested a different section (Eyde 1972). After comparing available morphological and chemical characters, Eyde (1988) was still uncertain about its placement within Alangium. According to our observation, wood of this species fits closely with that of sect. Marlea, not only in the type of perforation p1ates, but also in vessel element length and occurrence of paratracheal parenchyma. We therefore treat this species in sect. Marlea. Wood anatomy of the Comales has so far been studied independently within some families, such as Comaceae (Adams 1949), Nyssaceae (Titman 1949), and Garryaceae (Moseley & Beeks 1955), or broadly but using a limited number of twig sampies (Li & Chao 1954). The results ofthese studies were mainly interpreted using the classical Baileyan evolutionary trends of decreasing tracheary element length in advanced taxa, and of correlated changes in other wood anatomical features. Thus taxa with Ion ger andnarrowervessel elements having scalariformperforations with numerous bars were considered primitive (cf. Adams 1949). Majorregional studies of Comales include Kanehira (1926) and Yamabayashi (1938) for Japan and Korea, Tang (1936) forChina, Suzuki et al. (1991) for Nepal, Purkayastha & Bahadur (1977) for India, Moll & Janssonius (1914) and Philipson et al. (1980) for the Malesian region, Patel (1973) for New Zealand, and Sudworth & Mell (1911) and Panshin & De Zeeuw (1980) for North America. These studies are descriptive and do not include systematic analyses. In recent years studies of ecological trends