Platanus sp.

Wheeler, Elisabeth A. & Manchester, Steven R., 2021, A Diverse Assemblage Of Late Eocene Woods From Oregon, Western Usa, Fossil Imprint 77 (2), pp. 299-329 : 320

Platanus sp.

Text-fig. 10i–m

M a t e r i a l. UF 279-24552, minimum estimated axis diameter 30 cm.

D e s c r i p t i o n. Growth rings present, marked by noded rays, rows of radially narrow latewood fibers, and differences between vessel diameters between latest latewood and earliest earlywood. Wood diffuse-porous ( Text-fig. 10i ).

Vessels predominantly solitary, occasionally in oblique or tangential multiples; average tangential diameter 58 (9) µm, range 42–77 µm; 82–102 vessels/mm 2. Perforation plates predominantly simple ( Text-fig. 10j ), rare scalariform perforation plates with fewer than 15 bars ( Text-fig. 10l ); scalariform intervessel pits observed at ends of vessel elements, vessel-ray parenchyma pits horizontally elongated. Vessel element lengths average 499 (100) µm, range 260–740 µm.

Fibers non-septate, thick-walled.

Axial parenchyma diffuse, diffuse-in-aggregates, and in interrupted short uniseriate lines ( Text-fig. 10i ).

Rays of two distinct sizes, narrow rays 1–3-seriate (Textfig. 10m), larger rays to 24 cells wide and 6.6 mm high; heterocellular, body of procumbent cells with 1–4 marginal rows of square to upright cells. In radial section, some ray cells appear enlarged and possibly crystalliferous (Textfig. 10k).

R e m a r k s. We place this wood in Platanus , rather than Platanoxylon , because it has predominantly simple perforation plates like the extant genus, in contrast with woods of Platanoxylon / Plataninium , which have exclusively or predominantly scalariform perforation plates. The horizontally elongate vessel-ray parenchyma pits are not typical of extant Platanus but occasionally occur in the Vietnamese species P. kerrii GAGNEP. The occurrence of multiple types of Platanaceae woods agrees with the leaf and fruit record.

Coeval megafossils of Platanaceae from the late Eocene of Oregon include dispersed fruits with the distinctive basal tuff of hairs diagnostic of extant Platanus from the Teater Road locality (Manchester and Lott, pers. obs.). Also present in the region during the late Eocene are leaves of the extinct genera Macginitiea J.A.WOLfE et WEHR (and associated fruits of Macginicarpa which lack dispersal hairs, late Eocene of Gray Butte and middle Eocene Clarno Formation sites), Platameliphyllum N.MASLOVA (Clarno Formation sites; Huegele et al. 2022) Platanites E.fORBES (John Day Gulch locality of the Clarno Formation) as well as extant Platanus leaves (Clarno Formation sites).

Figures

Text-fig. 10. Platanoxylon cf. haydenii, a, e, h: UF 279-34470; b, c, d, f g: UF 279-34469. a, b: Diffuse porous wood with vessels solitary and in small multiples, which are mostly tangential or oblique, diffuse and diffuse-in-aggregates axial parenchyma., TS. c–e: Scalariform perforation plates. f, g: Opposite intervessel pits, TLS. h: Two size classes of rays, TLS. Platanus sp., UF 279- 24552. i: Predominantly solitary vessels, diffuse and diffuse-in-aggregates parenchyma, growth ring boundary distinct, noded rays, TS. j: Simple perforation plates (PP), RLS. k: Body of ray with procumbent ray cells, RLS. l: Scalariform perforation plate, RLS. m: Rays of two sizes, wide rays>10-seriate, TLS. Scale bars: 200 µm in a, b, h, i, m; 100 µm in j, k: 50 µm in c, d, e, f, l.