Liriodendron haueri ETTINGSHAUSEN

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 : 60-61

Liriodendron haueri ETTINGSHAUSEN

Pl. 3, Fig. 1–4, Pl. 6, Fig. 1

1869 Liriodendron haueri ETTINGSHAUSEN , p. 9, pl. 41, fig. 10–10b.

1961 Liriodendron procaccinii UNGER ; Knobloch, p. 273, pl. 7, fig. 1, 3.

1961 Styrax sp. ; Knobloch, p. 288, pl. 14, fig. 4.

Leaves broadly ovate with four lobes arising from a point one third of the blade width or only shallowly bilobate, leaf blade 41–82 mm long and 21 – ca. 90 mm wide, base widely cuneate, petiolate, petiole maximum 50 mm long. Midrib strong and straight, secondary veins arising at an angle of 40–50°, opposite or alternate, every second joined by a broken tertiary vein to the next vein above and then looping. Lowermost pairs sending fine outer loops towards the margin. Tertiary venation forms polygonal fields. Mesophyll tissue with small lens-shaped secretory cells, cuticles smooth, the abaxial surface with scattered stomata openings, otherwise cell structure poorly preserved.

D i s c u s s i o n. One aberrant leaf impression with only two shallow lobes was referred to Styrax by Knobloch (1961) but a similar leaf impression from Markvartice was assigned to Liriodendron on account of its epidermal anatomy ( Bůžek et al. 1976, pl. 3, fig. 8). Of the available names for fossil species of Liriodendron (see e.g. Archenegg 1894) we prefer here Liriodendron haueri ETTINGSHAUSEN rather than L. procaccinii UNGER (selected by Knobloch 1958, 1961) because the former name is based on a leaf impression from the Oligocene of North Bohemia (see Hably et al. 2001, p. 27, pl. 20, fig. 2, Akhmetiev et al. 2009, pl. 13, fig. 3) and was accepted by the previous authors dealing with other Palaeogene occurrences of Tulip tree foliage in this region (see e.g. Bůžek et al. 1976, Walther 1998). L. procaccinii is a common designation for fossil foliage of Liriodendron distributed mainly in Europe during the late Neogene (see Saporta and Marion 1876 – Meximieux, Knobloch 1998 – Willershausen). L. haueri differs from L. procaccinii in acute lobes contrary to mostly rounded lobes in the Italian Neogene populations ( Knobloch 1998, p. 14). Revision of the latter species type material from Senigallia, Italy ( Massalongo and Scarabelli 1859, Kustatcher et al. 2014) is required. Two extant species differ in the surface sculpture of the abaxial cuticle. The leaves in L. tulipifera L. from E and SE North America are abaxially smooth, in L. chinense (HEMSLEY) SARGENT from eastern China and Vietnam are papillate. In this respect our material looks to be similar to L. tulipifera .

It is noteworthy that in living species of Tulip tree the fruitlets survive in large quantities after the season under the trees while foliage readily decomposes over the winter. This is perhaps a reason why leaf impressions are less common than fruitlets in the fossil state (e.g., at Markvartice – Bůžek et al. 1976, Roudníky – Kvaček et al. 2014). This is however not the case at the Knížecí site, where no fruitlets have yet been recovered.

M a t e r i a l. Leaf impressions, NM-G2856a–f with cuticle, NM-G2859, NM-G2997, NM-G8591.