Platananthus synandrus Manchester
Plant Fossil Names Registry Number: PFN002767
Act LSID: urn:lsid:plantfossilnames.org:act:2767
Author: S. R. Manchester
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
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).
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.
Middle Eocene (Bridgerian vertebrate fauna)
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