Locality
Yukon-Koyukuk Basin Locality 11556
Description
Leaf: simple; symmetrical; oblate; apex rounded; base lobate; petiole normal; margin irregularly dentate or crenate except at base where entire; teeth irregular in size, shape, and spacing; apex glandular obtuse or rounded, sides convex or concave, sinuses rounded, teeth sometimes compound and bearing more than one gland; venation basal actinodromous with seven radiating major veins; primary midvein straight, moderate to stout; moderate secondary veins arise from the midvein in the apical half of the lamina, departing at 40-50°, may be slightly recurved initially becoming curved, brochidodromous or craspedodromous; a-pectinal vein moderate, slightly weaker than midvein, departing midvein at 35°, straight or curved, becoming irregularly abruptly curved at points of departure of abmedials, craspedodromous; a-abmedial veins moderate, irregularly curved, irregularly semicraspedodromous or craspedodromous; b-pectinals weak, very poorly developed, craspedodromous or irregularly curving to join basal a-abmedials; b-abmedials weak, irregular in course, craspedodromous or semicraspedodromous; g-pectinals weaker than b-pectinals, very poorly developed, irregularly curving or recurving, craspedodromous, g-abmedials irregular in course, weak craspedodromous or brochidodromous; d-pectinal vein very weak, forming angle of approximately 15o with g-pectinal vein, recurving then curving to join the basal g-abmedial vein, semicraspedodromous; d-abmedial veins very weak, brochidodromous; tertiary veins weakly developed, orthogonal to random reticulate, sometimes coalescing to form weak compound intersecondary veins; fourth order veins orthogonal.
Remarks
While obviously similar to the specimens assigned to form RAPE11 (Menispermites septentrionalis) these forms exhibit important differences.
The teeth of form RAPE11 are usually simple with a single gland at the tooth apex in contrast to the compound teeth and numerous glands on each tooth present here. The tooth venation in these specimens resembles that of form RAPE11 but is modified to supply the subsidiary glands on each tooth. The subsidiary glands are served by a third or higher order vein which departs directly from the vein supplying the apical gland, or by a semicraspedodromous branch of a looping higher order lateral. The most apical loops in the series of brochidodromous laterals may or may not join the medial vein immediately below the apical gland.
It is not only the tooth which has irregular venation. The entire leaf displays considerable variation in the behaviour of the pectinal veins and their abmedial branches. Some abmedials form brochidodromous loops and supply the teeth semicraspedodromously, while others run directly to the margin. It should be pointed out, however, that unless a specimen is well preserved the veins may appear to be craspedodromous. Hollick (1930) illustrates two examples of this form and assigns them to Menispermites reniformis. Hollick extended Dawson's (1883) original description although the margin details were still inadequate. The non-peltate base prompted Hollick (1930, p. 78) to question whether such leaves should be included in the genus. He pointed out that Berry (1911) had segregated the orbiculate peltate species into a group with the generic name Nelumbites Berry but disputed the wisdom of implying a relationship to the extant Nelumbo Adanson in view of the fact that the leaves are not necessarily symmetrically peltate and possess a midrib rather than like the 'Nymphaea'-Castalia group. Specimen USGS 11556.97 displays a petiole attached to attached to a thin stem. Such an arrangement is strongly suggestive of a climbing plant rather than an aquatic.