Locality

Amaam Lagoon Locality 1

 

Description

From Moiseeva (2012) (p. 88)

"Leaves simple, entire, sometimes with small lateral lobes; more developed lateral lobes ocur rarely. Leaf blade usually asymmetrical, from 3.5 cm to more than 14 cm long, 2.5–12.0 cm wide; medium sized leaves (7–9 cm long and 4.0–5.5 cm wide) are most widespread. Leaves are very variable in shape, predominantly elliptic ovate and elliptic; obovate and rounded, triangular and oblong ovate leaves occur as well. Leafbase asymmetrical, mostly cordate to variable extent, deeply cordate to nearly pseudopeltate;
sometimes it may be truncate or rounded. Leaf apex acute to acuminate; petiole up to 4 mm long and 0.5–0.7 mm thick is slightly widened near the leaf base.

Leaf margins serrate, frequently double serrate; secondary veins end in larger teeth, their branchlets in smaller ones. Small galeate teeth with broad base, convex basal and apical sides, acute or obtuse apex have sometimes terminal spinule and are angularly oriented relative to the leaf axis. Among teeth there are also comparatively narrow varieties with concave apical side. Being of variable dimensions, teeth are from 0.5 to 2.0 mm wide and from 0.5 to 2.0 mm high.

Venation pinnate, sometimes actimodromous, craspedodromous or semicraspedodromous, occasionally mixed. Lateral veins (7–13 pairs) arcuate or straight alternately branch from the midrib; in the lower half of leaves, their arrangement is nearly opposite. Two to three pairs of lower lateral veins are with connivent deviation points. Higher pairs are spaced wider (with interval up to 2.5 cm), and then intervening intervals gradually decrease toward the apex. Angles of deviation acute, gradually growing toward the leaf base (if leaf ovate),where basal veins depart practically at a right angle to the midrib. Comparatively thick basal veins are usually long, well ramified, ending at the apices of small lobes in larger leaves. All lateral veins have basiscopic branchlets, which are arcuate or straight in some cases, branching at the angles of 60°–70° (occasionally up to 90°). Two lower pairs of secondary veins have 7–10 branchlets; in higher pairs, number of the latter regularly decreases upward so that uppermost pairs have only one to two branchlets. In turn, basiscopic branchlets of basal veins may bifurcate several times. Tertiary venation opposite or alternate percurrent; tertiary veinlets form fine bifurcating anastomoses between secondary veins and their branchlets, which join veins of the higher order at a right angle. Venation of the fourth order polygonal reticulate; the respective ortho and pentagonal areolae are approximately equal in size. Inside areolae there are visible sometimes very fine curved and bifurcating veinlets of the fifth order."

 

Remarks

From Moiseeva (2012) (p. 88)

"Holotype: specimen figured by Kryshtofovich (1958b, pl. XIII, fig. 4; Fig. 53) from the Rarytkin Formation, Anadyr River basin (Rarytkin Range, Umkuveem River, outcrop 208)."