Cucurbitaciphyllum lobatum (KNOWLTON) Manchester, 2014

Manchester, Steven R., 2014, Revisions To Roland Brown’S North American Paleocene Flora, Acta Musei Nationalis Pragae Series B 70 (3 - 4), pp. 153-210 : 169-170

Cucurbitaciphyllum lobatum (KNOWLTON) comb. nov.

Text-figs 9.1–9.4

1924 Aralia lobata KNOWLTON, U. S. Geol. Surv. Prof. Paper 134, p. 93, pl. 17, figs 1, 2 (Basionym)

1962 Vitis lobata (KNOWLTON) R. W. BROWN , p. 82, figs 3, 7, 10.

Lectoype designated here: USNM 36675, fig. 1 of

Knowlton 1924.

Emended diagnosis. Leaves palmately trilobed, 3.5 to 15 cm long, 5 to 13 cm wide. Petiole narrow, not swollen at junction with lamina. Lamina base cordate. Lobes obovate, with smaller lobes and teeth along the margins; lobe apices acute. Sinuses of lobes and teeth usually rounded. Venation actinodromous, with a primary vein in each lobe, that of the central lobe symmetrically placed, those of the lateral lobes, placed asymmetrically, closer to the proximal margin. Often with an strong secondary or subprimary vein, arising near the base on abaxial side of the lateral primaries and feeding to a basal large tooth or small external lobe. Secondary veins pinnate in 7 to 9 pairs per lobe, camptodromous to semicamptodromous; lower pairs arising at 80 to 90° from the midvein and interconnecting to form an incomplete intramarginal vein (where the margin is untoothed); upper secondaries arising at narower angles (30–45°), craspedodromous where teeth are present. Intersecondary veins common. Tertiary veins percurrent to reticulate. Lower surface dotted impressions of numerous hair-like trichomes. Simple trichomes are seen as densely spaced protrusions on impression surfaces representing the lower surface of the lamina.

Jack Wolfe (cited in Raven and Axelrod 1974, p. 569) determined that Vitis lobata (KNOWLTON) BROWN (1962) clearly belongs to the Cucurbitaceae , but the characters leading to his conclusion were not stated. Wolfe’s identification is supported by the palmate lobing, scattered teeth, rounded lobal sinuses, partial intramarginal vein and simple trichomes scattered over the lamina surface. This architectural pattern occurs in more than one modern genus of the family, including Kedrostis , Melothria , and Zehneria . Accordingly, a new genus is established here to accommodate this species. This is significant because the fossil record of Cucurbitaceae is poorly known.

? Fagaceae

Brown attributed several leaf types to Fagaceae , including Castanea intermedia LESQUEREUX , Quercus asymmetrica TRELEASE , Q. greenlandica HEER , Q. macneilii R. W. BROWN , Q. sullyi NEWBERRY , and Q. yulensis R. W. BROWN. However , the affinities, even to the family level, are questionable as no unequivocal cupulate fruits of Fagaceae have been recovered. Quercus greenlandica was subsequently transferred to Fagopsiphyllum groenlandicum (HEER) MANCHESTER 1999. Q. yulensis also appears related to Fagopsiphyllum differing mainly by its more prominent teeth.

Leaves that Brown treated as Quercus sullyi NEWBERRY were subsequently treated as Dicotylophyllum flexuosum (NEWBERRY) J. WOLFE (1966) and then Meliosma longifolia (HEER) HICKEY (1977) , but most recently, they have been assigned to the extinct genus Dyrana GOLOVNEVA , as discussed herein under Platanaceae .

Betulaceae

Brown (1962) recognized two kinds of foliage assigned to the Betulaceae : Betula stevensonii LESQUEREUX , and Corylus insignis HEER. Betula stevensonii , established based on leaves from the Evanston Formation of southwestern Wyoming, might be Betulaceae , but the fine serration appears simple, rather than compound—unusual for Betula and for the family. The type locality is literally mined out and now occupied by a Walmart parking lot and adjacent lake. Although the attribution to Betulaceae may be correct, the assignment to Betula is questionable. None of the distinctive trilobed infructescence bracts of Betula have been observed in this or other Paleocene sites of the Rocky Mountains or Great Plains region, but they are frequently found with fossil leaves of Betula leopoldae from the Eocene of Washington ( Crane and Stockey 1987).