Acer angustilobum HEER

Kvaček, Zlatko, Teodoridis, Vasilis & Zajícová, Jana, 2015, Revision Of The Early Oligocene Flora Of Hrazený Hill (Formerly Pirskenberg) In Knížecí Near Šluknov, North Bohemia, Acta Musei Nationalis Pragae Series B 71 (1 - 2), pp. 55-102 : 69

Acer angustilobum HEER

Pl. 6, Fig. 7, Pl. 18, Fig. 2–3

1859 Acer angustilobum HEER , p. 57, pl. 117, fig. 25a, pl. 118, fig. 4–9.

1961 Acer cf. angustilobum HEER ; Knobloch, p. 285, pl. 9, fig. 4, pl. 11, fig. 4.

Leaves deeply tricuspidate, blades 19 to more than 65 mm long and 22–74 mm wide, lobes of almost the same width, with subparallel margins, widely simple dentate. Abaxial cuticle fine papillate.

D i s c u s s i o n. Maple leaves with a prominently double dentate middle lobe have usually been assigned to Acer palaeosaccharinum STUR but transitional forms connect them with typical Acer angustilobum with only simple dentation on the main lobe. Both fossil morpho-types are connected with transition as expressed in the Procházka’s monographs ( Procházka 1952, Procházka and Bůžek 1975) by establishing infraspecific taxa ( Acer palaeosaccharinum forma subplatanoides PROCHÁZKA et BŮŽEK and forma subdasycarpoides PROCHÁZKA et BŮŽEK ). We apply the same system as in Knobloch (1961) and maintain both fossil species independently. The epidermal structure obtained from one fragmentary specimen corresponds exactly to the structure described for A. angustilobum from Seifhennersdorf ( Walther and Kvaček 2007, p. 117). We follow this treatment stressing that foliage from the České středohoří Moutains assigned to A. angustilobum is difficult to discriminate from some forms of A. palaeosaccharinum as described below, which differ in epidermal anatomy ( Walther 1972).

M a t e r i a l s t u d i e d: Leaf impressions, NM-G2877,

NM-G2993, NM-G8607, NM-G11505a, b, EK 363–371.