Anacostia E.M.Friis, P.R.Crane et K.R.Pedersen

Plant Fossil Names Registry Number: PFN001277


Authors: E. M. Friis, P. R. Crane & K. R. Pedersen

Rank: genus

Reference: Friis, E. M., Crane, P. R. & Pedersen, K. R. (1997): Anacostia, a new basal angiosperm from the Early Cretaceous of North America and Portugal with trichotomocolpate/monocolpate pollen. – Grana 36: 225–244.

Page of description: 227

Type taxon

Anacostia marylandensis E.M.Friis, P.R.Crane et K.R.Pedersen

Original protologue

Fruiting unit unilocular with a single seed, semicircular to elliptical or irregular in outline; laterally flattened with a straight or convex ventral margin and a strongly convex dorsal margin. Stigma indistinct, apparently sessile. Fruit wall thin, without mechanical tissue; outer epidermis consisting of equiaxial or slightly elongate, polygonal cells with straight anticlinal walls and a striate outer cuticle, sometimes with a central papillate protrusion. Seed anatropous, basally attached; chalaza not visible on the outer surface of the seed; seed wall with a smooth, shiny outer surface. Seed wall apparently bitegmic, formed from two cutinized tissues; outer tissue (testa) sclerenchymatous, consisting of an outer layer of cuboid to palisade-shaped cells with strongly thickened and straight cell walls, a middle layer of shallow cells with thickened and strongly digitate anticlinal walls, and an inner epidermis of shallow cells with straight cell walls; inner tissue (tegmen) thin, membranous and crushed, with transversely aligned thickenings of the tangential cell walls. Pollen (adhering to stigmatic area and surface offrait wall) symmetrical to asymmetrical, monoaperturate with a trichotomocolpate or monocolpate aperture; pollen tectate with graded, reticulate to foveolate tectum and lumina that decrease in size towards the aperture margin and proximal pole; columellae short, densely-spaced, and supporting the psilate muri.


From the Anacostia River which passes close to the locality where the type species was recovered.

Plant fossil remain

macro- and meso-fossils-embryophytes except wood

Names associated with genus

Anacostia portugallica E.M.Friis, P.R.Crane et K.R.Pedersen 1997

Anacostia teixeirae E.M.Friis, P.R.Crane et K.R.Pedersen 1997

Anacostia marylandensis E.M.Friis, P.R.Crane et K.R.Pedersen 1997

Anacostia virginiensis E.M.Friis, P.R.Crane et K.R.Pedersen 1997