Locality
Yukon-Koyukuk Basin Locality 11554, 11556
Description
Leaf: simple (?); symmetrical; very narrow elliptic; apex acute with a more or less rounded tip, base missing; margin entire; venation pinnate, camptodromous; primary midvein moderate to weak, straight; secondary veins weak, departing midvein at approximately 40-45°, initially straight, curving near margin to join superadjacent secondary at an acute to obtuse angle, brochidodromous; intersecondary may be pesent; tertiary venation percurrent, more or less straight; weak, slightly convex in axils of secondaries, forming an acute angle with abmedial sides of secondaries and an obtuse angle with admedial side, angle to midvein decreasing near margin; fourth order venation weak, random to orthogonal reticulate.
Remarks
This specimen is similar to 'Ficus daphnogenoides' (Heer) Berry illustrated in Hollick (1930), Plate 39, Figs. 3-5. This form also compares well with a specimen figured by Hollick (1930; Plate 45, Fig. 3; Plate 73, Fig. 4c) which he refers to 'Laurus' antecedens Lesquereux (1892; Plate 11, Fig. 3, p. 92). Lesquereux's specimen, however, has a distinctly acute apex and is lanceolate, the nervation appears more eucamptodromous and the secondary veins are distinctly curved along their entire length. Such features are not seen in Hollick's (1930) specimens or those which are described here.
A better comparison can be made with 'Laurus' angusta as reported from the Dakota Group by Lesquereux (1892, p. 33; Plate 16, Fig. 7) which differs only in that it has a more narrowly acute apex. However, Lesquereux failed to illustrate or describe the tertiary veins which in Heer's specimens (Heer 1882, vol. 6, p. 76; Plate 20, Figs. 1b, 7) are reticulate, poorly differentiated from higher vein orders, and lack any tendency to a transverse orientation. Lesquereux's determination must therefore be in doubt. Comparison should also be made with Daphnophyllum dakotense Lesquereux (1892, p. 99; Plate 51, Figs. 1-4; Plate 51, Fig. 1).
More recently acess to Russian material means that this specimen should be referred to Myrtophyllum acuminata (Philippova) Herman.