Platananthus synandrus Manchester

Plant Fossil Names Registry Number: PFN002767


Author: S. R. Manchester

Rank: species

Genus: Platananthus Manchester

Reference: Manchester, S. R. (1986): Vegetative and Reproductive Morphology of an Extinct Plane Tree (Platanaceae) from the Eocene of Western North America. – Botanical Gazette 147(2): 200–226., link

Page of description: 212

Illustrations or figures: figs 24B, 45, 46, 48–53, 58–65

Name is type for

Platananthus Manchester 1986


Holotype IU 5150, Indiana University, Bloomington, USA
Figures: figs 46, 48–53

Note: Holotype description: a well-preserved, silicified inflorescence, serially peeled both transversely and longitudinally to show floral structure.

Paratypes: Uncataloged USGS specimen, (locality USGS-8637 = West Branch Creek), compression specimen, most complete axis known, showing 10 sessile heads (preparations failed to yield pollen); IU 5145 (OMSI-230), incomplete axis showing five sessile heads (fig. 24B) that yield clusters of pollen (fig. 26) on maceration, on slab adjacent to a pistillate axis; IU 5151 (OMSI-225) (fig. 45), IU 5152 (OMSI-225), additional petrifactions; IU 5180 (OMSI-228), compression with intact pollen (figs. 58–65).

Original diagnosis/description

Globose heads borne in helical arrangement on axes >12 cm long (longest specimen incomplete) with at least 10 sessile heads 3.5–8.0 mm in diameter. Head composed of a receptacular core 2.5–3 mm in diameter surrounded by numerous florets, each with a whorl of five stamens, surrounded by a prominent perianth. Stamens have elongate anthers (0.9–2.2 mm long) with lateral dehiscence, sessile or on very short filaments, and elongate, conical peltate connectives. Four pollen sacs in two pairs per anther, 1.5–2 mm long. Connectives parenchymatous, except for a central vascular strand and a well-cutinized epidermis. Numerous hairs arising from the connective epidermis and intertwining with those of adjacent connectives so that the five stamens of each floret are united and shed as five-stamen units after pollen dehiscence. Perianth well developed and enclosing each floret prior to anthesis, with numerous (ca. 15–25) free strap-shaped tepals in apparent spiral arrangement, 0.4–0.7 mm wide and 2.5–3.0 mm long. In situ pollen is tricolpate and prolate, 12–16 μm long, 10–14 μm equatorial diameter. Colpi ca. two-thirds as long as the polar diameter. Exine finely reticulate, tectate columellate. Tectum 0.2–0.3 μm thick, composed of elements that are triangular in longitudinal section. Foot layer 0.3–0.4 μm thick. Endexine not preserved.


Paleogene, Eocene
Middle Eocene (Bridgerian vertebrate fauna)


United States
OMSI-225: Clamo Nut Beds. SW 1/4, SE 1/4, Sec. 27, T.7S, R.19E, Wheeler County, Oregon

Plant fossil remain

macro- and meso-fossils-embryophytes except wood


Use comments to notify PFNR administrators of mistakes or incomplete information relevant to this record.