Tanispermum

Name

Tanispermum

Rank

Genus

Authors (Pub.)

Friis E. M. Crane P. R. Pedersen K. R.  

Publication

Tanispermum, a new genus of hemi-orthotropous to hemi-anatropous angiosperm seeds from the Early Cretaceous of eastern North America [2018/8]

Journal

American Journal of Botany

Volume

105

Issue

8

Page number

1371

Year

2018

Parent Taxon

[Class] Magnoliopsida

Fossil Status

fruits (with seeds)

Type

Tanispermum hopewellense

Diagnosis

Fruit one-or two-seeded, indehiscent, with a thin fruit wall. Isolated seeds single or in pairs, small, bitegmic, and exotestal. Seeds irregularly elliptical, either with a single flattened contact face from the other seed, or with evenly rounded faces. Hilum and micropyle widely spaced and seeds hemi-orthotropous to hemi-anatropous. One set of vascular bundles extends from the hilum to chalaza (raphe). Micropyle in the inner integument (tegmen) differentiated into a thickened plug, and in the outer integument seen as a small irregular, lobed opening. Testa formed from an outer layer of tall palisade-shaped sclerenchyma cells (exotesta) and an inner zone of thin-walled, loosely packed cells (mesotesta/ endotesta), several cell layers deep. Anticlinal walls of the palisade cells unevenly thickened, thicker toward the inside resulting in an obconical cell lumen or thicker toward the outside resulting in a conical cell lumen. Exotestal cells with undulate outer and inner parts of anticlinal walls resulting in stellate-undulate facets and a jigsaw puzzle-like pattern on the seed surface and the inner surface of the exotesta. Tegmen thin except close to the micropyle where it is sclerified. Embryo small. Nutritive tissue cellular.