USGS11614.3 Trochodendroides arctica (Heer) Berry HATR123


USNM 406673



Locality Map


Lat. 60° 36' 36"N  Long. 164° 49' 18"W

Baird Inlet (C-8) Quad. Nelson Island.


Leaf:  simple; symmetrical; very wide ovate; apex acute, slightly acuminate; base rounded to very shallowly lobate with a decurrent junction to the petiole; petiole normal, short; margin crenate, except near the base where entire, teeth irregular in size and arrangement, apices rounded, sinuses angular, axes of teeth with a slight apical orientation; venation basal imperfect acrodromous; primary midvein moderate, more or less straight; pectinal veins moderate, arising from the midvein at an angle of 40o and running two-thirds of the length of the leaf then curving in towards the midvein to join a looping superior secondary vein at an acute angle; pectinal abmedials arising at angles of 50-60°, uniformly curved until close to the margin where they curve back towards the midvein to join the superadjacent secondary vein at an obtuse angle in the basal half of the lamina, becoming acute towards the apex; superior secondary veins arising from the midvein in the apical half of the lamina are uniformly curved until approximately halfway between the midvein and the margin where they curve abruptly to join the superadjacent secondary vein at an acute angle; tertiary arches present on the abmedial side of the marginal secondary loops and tertiary veins from the nearest point of the loops to the margin forming the midveins of the teeth (semicraspedodromous), tertiary veins between midvein and pectinals moderate, in the lower half of the lamina percurrent convex forming acute or right- angled junctions with pectinal veins and acute angles with the midvein, often branching once; tertiary veins between the pectinal and pectinal abmedial veins percurrent, more or less straight and apparently simple.


This form is clearly of the Trochodendroides/'Cercidiphyllum' type with an architecture very similar to that of the polymorphic leaves of the modern Cercidiphyllum japonicum Siebold and Zuccarini.  Details of tooth venation were not preserved in these specimens.