Latitudinal trends in wood anatomical characters in three Asiatic species of Cornus sensu lato (s.l.) were studied and compared with those for the whole genus based on an extensive sampling covering the specific distribution ranges and the generic data from a previous study. We studied 124 specimens of C. controversa growing between 31.5° and 45.3° N, 54 of C. kousa between 24.4° and 40.5° N, and 64 of C. macrophylla between 27.8° and 41.0° N. Characters studied were vessel element length, fiber length, vessel frequency, tangential vessel diameter, and vessel grouping index. At the species level no latitudinal trends were detected throughout the distribution ranges of the species. Neither tree size, altitude, nor climatic factors had a significant correlation with wood anatomical characters. In contrast, at the genus level, latitudinal trends were significant not just for the whole genus, but for both New and Old World species groups. At the genus level, latitude and three climatic factors all had a significant correlation with wood anatomical characters, but correlation coefficients with latitude were markedly high. The difference in latitudinal trends between the genus and species levels may be due to the radiation of Cornus along paleoclimatic gradients in the early Tertiary.

Axial parenchyma (excl. epithelial and subsidiary cells of intercellular canals)p. 35 72. Present Arrangement of axial parenchymap. 37 73. Diffuse (evenly scattered throughout the entire growth increment) 74. Tangentially zonate 75. Marginal Transverse end wallsp. 39 76. Smooth 77. Irregularly thickened 78. Beaded or nodular RAY COMPOSITION Ray tracheidsp. 40 79. Commonly present 80. Absent or very rare Cell walls of ray tracheidsp. 43 81. Smooth 82. Dentate 83. Reticulate Ray tracheid pit borders angular or with dentate thickenings (radial section, Larix & Picea only)p. 45 84. Present End walls of ray parenchyma cellsp. 47 85. Smooth (unpitted) 86. Distinctly pitted Horizontal walls of ray parenchyma cellsp. 48 87. Smooth (unpitted) 88. Distinctly pitted Indenturesp. 49 89. Present CROSS-FIELD PITTING Cross-field pitting (according to Phillips 1948, amended by Vogel 1995)p. 51 90. "Window-like" (fenestriform) 91

The wood anatomy of Comaceae, Alangiaceae, Garryaceae, and Nyssaceae constituting the Comales in the sense of Cronquist (1981, 1988) is described in great detail and subjected to a cladistic analysis. A microscopic identification key to the woods studied is given. The alliance includes 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 account. The character states ultimately recognised in these continuously varying quantitative characters coincide with intergeneric or intersectional gaps. The cladistic analysis based on a datamatrix with twentyone 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 Daphniphyllum (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, Aralidium, Aueuba, Corokia, Garrya, Griselinia, Helwingia, Melanophylla and Toricellia, constitute a second, well-supported clade. Two Hydrangea 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 rbcL sequences by Xiang and co-workers. The infrageneric classification of Cornus, Alangium and Nyssa is also discussed.

Latitudinal or altitudinal variation in several anatomical characters of wood is common for woody dicotyledonous genera with a wide distribution, but whether such variation exists at the species level is disputed. Latitudinal and altitudinal trends in wood anatomy of Dodonaea viscosa were studied, using 102 samples collected between 41.2° S and 33.3° N latitude and 7-2750 m altitude. We studied variation in four quantitative features: vessel element length, fiber length, vessel frequency, and tangential vessel diameter. Ontogenetic trends were minimal with a slight decrease or increase in the innermost stem and were negligible among the studied specimens. Throughout the distributional range of the species, no latitudinal trends were detected in either the Northern or Southern Hemispheres. Altitudinal trends were also nonexistent, except for two features in specimens from China and Japan. Absence of latitudinal or altitudinal trends in this widely distributed species suggests that in some species the species-level variation in wood anatomy is not controlled by ecological gradients.