SYSTEMATIC WOOD ANATOMY OF CORNACEAE AND ALLIES

The wood anatomy of Cornaceae, Alangiaceae, Garryaceae, and Nyssaceae constituting the Cornales in the sense of Cronquist (1981, 1988) is de scribed in great detail and subjected to a cladistic analysis. A micro scopic identification key to the woods studied is given. The alliance in eludes seventeen genera, mostly of trees and shrubs, very rarely he rbs. Although wood anatomically fairly homogeneous, variation exists i n both qualitative and quantitative characters. Some of the latter sho w distinct latitudinal trends within individual genera, and character states have only been recognised taking their latitudinal dependencies into account. The character states ultimately recognised in these con tinuously varying quantitative characters coincide with intergeneric o r intersectional gaps. The cladistic analysis based on a datamatrix wi th twenty-one characters (Table 3) and using Cercidiphyllum, Daphniphy llum, and Hamamelis as outgroups yielded a strict consensus tree with a quadrichotomy with two monophyletic clades, Hydrangea paniculata (a representative of the closely allied Hydrangeaceae) and Daphniphyllum (Fig. 81). One weakly supported clade includes Alangium, Camptotheca, Cornus, Curtisia, Davidia, Diplopanax, Mastixia, and Nyssa without any robust lineages among them. The other genera, Aralidium, Aucuba, Coro kia, Garrya, Griselinia, Helwingia, Melanophylla and Toricellia, const itute a second, well-supported clade. Two Hydrangea taxa included in t he analysis nest in the second clade and a basal branching respectivel y. The wood anatomical diversity pattern thus supports a family concep t of Cornaceae including Cornus, Curtisia, Diplopanax, Mastixia, Alang iaceae, and Nyssaceae, and exclusion of the genera in the other clade. There is remarkable agreement between some of these wood anatomical r esults and recent cladistic analyses of rbcL sequences by Xiang and co -workers. The infrageneric classification of Cornus, Alangium and Nyss a is also discussed.