Alnus usyuensis

Name

Alnus usyuensis

Rank

Species

Generic Name

[Genus] Alnus

Authors (Name)

Huzioka K.  

Authors (Pub.)

Tanai T.  

Publication

Neogene floral change in Japan [1961/3]

Journal

Journal of the Faculty of Science of the Hokkaido University

Volume

11

Issue

2

Page number

283

Year

1961

Fossil Status

leaves

Stratigraphy

Miocene

Location

Soya-magaribuchi coal mine, Wakkanai City, and Kinoko, Kaminokuni-mura, Hiyama-gun, Hokkaido, Japan

Paleoregion

Eurasia (Japanese Archipelago)

Data for Syntypus

Repository

National Museum of Nature and Science, Palaeobotany Collection, Tokyo, Japan

Diagnosis

Leaves variable in size, slightly inequilateral, oval to elliptical-oval in outline, 3.0 to 12 em long and 2.2 to 8.5cm wide; apex abruptly acute or pointed ; base somewhat asymmetrical, broadly to strong- Iy cordate; midrib stout, straight to the apex; secondary nerves rather slender, 9 to 12 subopposite ,pairs, diverging from the midrib at angles of about 60 degrees on the middle part of blade and about 3e degrees on the upper, 2 or 3 basal pairs of secondaries short, more densely arranged than the others, diverging from the midrib at right angles or more; all secondaries nearly straight or gently eurving up, entering into marginal large teeth; a few tertiaries branching from the secondaries near the margin, then entering into marginal small teeth; tertiar'ies among inter-secondary spaces distinetly percurrent; nervil}es obscure, forming fine polygonal meshes; margin duplicately serrate, with acute or bluntly pointed teeth; texture thin, membranaceous; petiole stout and thick, 1,O to 1,8 cm Iong. Psilitate cones ellipsoidal in general outline, 1.7 to 2,7 cm high and l,3 to 1,7 cm wide; cone-seales wedge-shaped in outline, 4 to 5 mm high, gently arched at the distal margin, ornamented by some rigid longitudinal ridges; peduncle stout, about 2 mm thick, more than 1 cm long.