Platanus rileyi O.M.Ball

Plant Fossil Names Registry Number: PFN003171

Act LSID: urn:lsid:plantfossilnames.org:act:3171

Author: O. M. Ball

Rank: species

Reference for this name: Ball, O. M. (1939): A Contribution to the Paleobotany of the Eocene of Texas II. – Bulletin of the Agricultural and Mechanical College of Texas 10(3): 1–55.

Original diagnosis/description

Leaves of large size, uniformly broadly truncate, the maximum being 20 centimeters from top of petiole to tip of middle lobe and 25 centimeters from tip to tip of the lower lobes; palmately 5-7 lobed, the lobes fairly uniform in size and shape. The lobes are narrowly acuminate and are separated by broad but shallow sinuses. The margins seem to be very entire except near the tips of the lobes where a few aciculate teeth appear in some specimens. However, the coarseness of the matrix might very well obscure small dentition, were such present. The base, at the point of union with the petiole, is usually cuneate. A number of specimens bear a remarkable well developed basal lobe or "apron". This structure is triangular in shape, 2 or 3 ribbed and lobed. The lobes are narrowly lanceolate in shape, denticulate in their upper third and the Sinuses are deep, extending to two-thirds of the length of the “apron.” No petiole is present in any of the many specimens at hand.
The venation is triple-nerved from the top of the petiole, the three primaries being of about the same size. A few centimeters above the base, the outer primaries each give off a stout secondary which passes out into the lower lateral lobe. A short distance above the origin of this vein, a single tertiary arises from its outer side and passes out to a more or less evident lobe at the margin. The angle of divergence in all these is 35". From the stout middle primary arise 7 or 8 secondaries on each side, the lower 3 or 4, widely alternate; the upper, more nearly opposite. This arrangement is repeated in the lateral primaries and secondaries. The veins of this order form a series of arches along the margins.

Etymology

"Collected by Claude Riley, after whom, in recognition of his tireless zeal in collecting fossils, I have named the species." - O.M. Ball (1939)

Locality

United States
Fayette Sandstone, Bedias Creek, Grimes County, Texas.