Locality
Yukon-Koyukuk Basin Locality 11561
Leaf: simple; symmetrical; shape variable often very wide ovate; often margins inflated at termination of pectinal veins; apex obtuse; base missing; margin dentate; teeth somewhat irregular in size and spacing, apices angular, glandular, obtuse, sides concave, sinuses shallow, rounded; primary midvein straight or nearly so, moderate; pectinal veins suprabasal, weaker than midvein, departing at 30-50°, straight, slightly recurved or irregular in course, craspedodromous; abmedial veins moderate departing pectinal at 35-45°, curved sometimes irregularly, predominantly craspedodromous, more basal abmedials branched abmedially or forked near margin; superior secondaries more or less opposite, moderate, curved, may be recurved in part, departing midvein more or less parallel to pectinal veins, craspedodromous, may be branched ad- and abmedially, frequency of branching increasing basally, branches craspedodromous; inferior secondaries weak, recurved; tertiary veins moderate, simple or forked, predominantly convex but may be straight or concave, usually recurrent but orthogonal reticulate in places; fourth order veins orthogonal, percurrent, simple or forked.
These specimens have been described together but may not represent leaves of the same biological species. They all display some similarities but lack complete bases which provide the most diagnostic set of characters. In general form they are similar to the more apical portions of specimens USGS 11561.8, USGS 11561.7 (form HAPLP19), USGS 11561.1 (form HAPLP21) but differ in having more irregular dentition and are distinguishable from other peltate or lobate hamamelid-like leaves in having irregular or irregularly curved (rather than smoothly curved) pectinal veins. The opposite superior secondary veins, the behaviour of the pectinal veins, and the venation near the base all suggest a close relationship with form HAPLD26. Comparison with previously published forms indicates that the specimens could represent Pseudoprotophyllum venustum Hollick (1930, p. 92; Plate 73, Fig. 1), Populites platanoides Hollick (1930; Plate 36, Fig. 3, not Plate 34, Fig. 5) or 'Platanus' valida (Hollick, 1930, p. 84; Plate 75, Fig. 2).
