Lithocarpoxylon 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 : 310

Lithocarpoxylon sp.

Text-fig. 5h–l

M a t e r i a l. UF 279-84864.

D e s c r i p t i o n. Growth rings indistinct to distinct. Semi-ring-porous to diffuse-porous.

Vessels in radial to slightly diagonal alignment; exclusively solitary, round to oval in outline ( Text-fig. 5h, i ), mean tangential diameter of the vessels in the first half of the growth ring 122 (22) µm, 67–166 µm. Predominantly simple perforation plates, one scalariform perforation plate with fewer than 10 bars observed ( Text-fig. 5k ). Vesselray parenchyma pits with reduced borders and commonly vertically elongated ( Text-fig. 5l ). Thin-walled tyloses common.

Axial parenchyma apotracheal diffuse, diffuse-inaggregates ( Text-fig. 5h, i ), 4–8 cells per strand.

Vasicentric tracheids present ( Text-fig. 5j, l ).

Rays uniseriate and aggregate ( Text-fig. 5j ), homocellular composed of procumbent cells. Aggregate rays composed of 1–8-seriate rays, loosely associated ( Text-fig. 5j ). Uniseriate rays 3–11–16 cells high; uniseriate rays>12 per mm.

Crystals not observed.

C o m p a r i s o n s w i t h e x t a n t w o o d s. The rationale for assigning this sample to Lithocarpoxylon is the same as that for UF 279-24559 described above. This sample differs in having more frequent aggregate rays composed of wider individual rays and narrower vessels.

C o m p a r i s o n s w i t h f o s s i l w o o d s. Most other species of Lithocarpoxylon , with the notable exception of Lithocarpoxylon microporosum Y.M.CHENG, Y. f.WANG, f.X.LIU, R.C.MEHROTRA, X. M.JIANG, C.S.LI et Y.G.JIN from the Pliocene of Yunnan, China ( Cheng et al. 2018), have wider vessels than this Post Hammer wood; most also have rays greater than 10 cells wide or compound rays. For now, we are hesitant to assign this wood to a new species based on differences in quantitative features.

Figures

Text-fig. 5. Lithocarpoxylon ashwillii sp. nov., UF 279-24544. a, b: Semi-ring porous wood, exclusively solitary vessels in a radial/ diagonal arrangement, diffuse axial parenchyma, TS. c: Homocellular rays composed of procumbent cells; vasicentric tracheids; vesselelements with simple perforation plates (PP), TLS. d: Vessel-ray parenchyma pits (VRP) with reduced borders, vertical,RLS. e: Crystalliferous axial parenchyma strand (C) with a single crystal per chamber; ray with procumbent cells, RLS. f: Aggregate ray (right) composed of loosely associated 1–2-seriate rays, TLS. g: Uniseriate rays, thin-walled tyloses in vessels, vasicentric tracheids (VT). Lithocarpoxylon sp., UF 279-84864. h, i: Semi-ring porous wood, exclusively solitary vessels in radial arrangement. j: Aggregate ray and uniseriate rays. k: Scalariform perforation plate with fewer than 10 bars. l: Vessel-ray parenchyma pits with reduced borders to simple, vertical. Scale bars: 200 µm in a, b, f, h, j; 100 µm in c, i; 50 µm in d. e; 20 µm in k, l.