Protopteris STERNBERG 1838

Greguš, Josef, Kvaček, Jiří & Halamski, Adam T., 2013, Revision Of Protopteris And Oncopteris Tree Fern Stem Casts From The Late Cretaceous Of Central Europe, Acta Musei Nationalis Pragae Series B 69 (1 - 2), pp. 69-83 : 71

Genus Protopteris STERNBERG 1838

Type: Lepidodendron punctatum STERNBERG 1820, p. 20 , 23, pl. 4, fig. 1 ≡ Protopteris punctata (STERNBERG) C. PRESL in STERNBERG 1838, p. 170, pl. 65, figs 1-3.

E m e n d e d d i a g n o s i s. Stem casts with leaf scars helically arranged, each leaf scar bearing one horseshoe shaped continuous scar of vascular bundle.

D i s c u s s i o n. The genus Protopteris is defined from mostly Mesozoic tree fern taxa. It differs from the genus Protocyathea O. FEISTMANTEL 1877 in having one continuous vascular bundle scar. Leaf scars of the genus Protocyathea bear vascular bundles forming several small irregular pits resembling leaf scars of the extant genus Cyathea J.E. SMITH 1793 .

The genus Protopteris differs from Oncopteris in having leaf scars helically arranged. The genus Oncopteris has leaf scars in longitudinal rows having two scars of vascular bundles. However, vascular bundles are not very reliable characters as already pointed out by Schenk (1871), because their shape and number can vary considerably ( Pfefferkorn 1976). Protopteris differs from the Palaeozoic genus Megaphyton ARTIS 1825 in having more than two rows of leaf scars on the mature stem. Another Palaeozoic genus Caulopteris LINDLEY et HUTTON 1832 also has leaf scars helically arranged as in Protopteris , but the scars of Caulopteris also form rows, which is not the case in Protopteris . Additionally, both of the Palaeozoic genera have much larger leaf scars and vascular bundles than the genera Oncopteris and Protopteris .