Locality
USGS11614
Lat. 60° 36' 36"N Long. 164° 49' 18"W
Baird Inlet (C-8) Quad. Nelson Island.
Description
Leaf: simple; asymmetrical; wide elliptic; apex missing; base lobate; margin crenate, teeth irregular in size and arrangement; apices and sinuses rounded, apparently lacking any apical swollen cap or gland; venation marginal imperfect basal actinodromous; primary midvein moderate more or less straight; a-pectinals weak, more or less straight, arising at an angle of 40° on one side and 50° on the other and forked near the margin; a-pectinal abmedials arising at angles of 50° on the side where the a-pectinal diverges from the midvein at 40° and at 70° on the other, often forked near margin, the most basal a-pectinal abmedials arising from the point of departure of the a-pectinals and recurved into the basal lobes, branched abmedially to form weak b-pectinals; b-abmedials looped near margin, basal b-abmedials branched abmedially to form very weak g-pectinals, g-abmedials looped; superior secondary veins moderate, straight, forked near the margin and running parallel to the a-pectinals; tertiary veins convex, percurrent, usually simple but sometimes branched, often forming more acute angles with the admedial side of a secondary vein than with the abmedial side.
Remarks
In extant hamamelid leaves the crenate margin occurs in the Cercidiphyllales which, like the Trochodendrales, are distinct from the other hamamelids in having Chloranthoid teeth. Unfortunately this leaf is not well enough preserved to determine the tooth type. The pectinal veins are short and weak giving the leaf a pinnate appearance, which is not seen in the Cercidiphyllales but rather is a feature of the Trochodendrales. For these reasons this leaf is tentatively included in the trochodendralean-like group until such time as additional specimens prove otherwise. Krassilov (1979) figures a specimen of a leaf base similar to that possessed by this form under the name Cissites sp. cf. 'Vitis' cretacea Vachrameev (Krassilov, 1979; Plate 30, Fig. 12). Krassilov's specimen differs in having curved (acrodromous?) a-pectinals and stronger b- and g-pectinals supporting at least some craspedodromous abmedials. Krassilov's specimen is probably of approximately Coniacian age based on the forms found associated with it (Trochodendroides sachalinensis (Kryshtofovich) Kryshtofovich, Protophyllocladus sachalinensis (Kryshtofovich and Baikovskaja) Krassilov, Cupressinocladus cretaceous (Heer) Seward, Sequoia reichenbachi).