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Acer stewarti
Taxonomy
Acer stewarti was named by Wolfe and Tanai (1987) [Encompasses leaves and fruits ]. Its type specimen is UAPC S485, a leaf, and it is a compression fossil. Its type locality is One Mile Creek, north of Princeton, which is in a Ypresian lacustrine horizon in the Allenby Formation of Canada.
Sister species lacking formal opinion data
Synonymy list
| Year | Name and author |
|---|---|
| 1987 | Acer stewarti Wolfe and Tanai |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Acer stewarti Wolfe and Tanai 1987
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| J. A. Wolfe and T. Tanai 1987 | Leaves simple, perfectly actinodromous; shallowly 5-lobed, with the most basal lobes as deeply incised as the teeth of the more apical lateral lobes; leaves oval, over 6.5 cm long (none complete) and 6.0 cm wide; most apical pair of lateral primary veins slightly diverging from medial secondary veins, almost straight, craspedodromous; 4 to 5 secondary veins departing at angles of 30° to 40° from basal side of most apical lateral primary, straight to slightly curving, craspedodromous; at least 4 pairs of medial secondary veins, straight, craspedodromous; tertiary veins between most apical lateral primary veins and midrib widely spaced, compound, and slightly A-A; tertiary veins between secondary veins widely spaced, compound, and R-R; fourth order venation forming areoies, irregularly polygonal, with thin veinlets that branch 1 to 2 times; lobal sinal bracing formed by a compound tertiary vein; teeth large, 0-1 and markedly attenuate; petiole more than 0.4 cm long.
Fruits samaroid, nutlet at basal end. Nutlets 0.7 to 0.9 cm long, 0.3 to 0.5 cm wide, outline circular, concave-convex; thin, poorly defined flanges, but otherwise nutlet almost smooth, with 3 to 4 indistinct veins parallel to long axis of nutlet and connected by widely spaced anastomoses; attachment angle about 40°, nutlet angle about 20°; proximal margin of nutlet slightly expanded beyond proximal margin of wing. Wing 1.5 to 2.3 cm long, 0.7 to 1.1 cm wide; proximal margin straight, distal margin broadly convex, forming a broadly V-shaped sulcus with nutlet; proximal margin with 5 or 6 prominent veins that extend from the apical margin of nutlet; wing veins diverging from proximal margin at angles of 10° to 20°, curving markedly convexly, dichotomizing 5 to 6 times. few anastomoses or veinlets. |