Ptelea cf. trifoliata Linnaeus, 1753

Stults, DZ & Axsmith, BJ, 2015, New plant fossil records and paleoclimate analyses of the late Pliocene Citronelle Formation flora, U. S. Gulf Coast, Palaeontologia Electronica (New York, N. Y.: 1991) 2 (6), pp. 1-35 : 20

Ptelea cf. trifoliata Linnaeus, 1753

Figure 7.3

Description. One mostly complete leaflet is identified as Ptelea , possibly P. trifoliata . The leaflet is ovate and nearly circular (in the Gulf of Mexico Coastal Plain, this is a characteristic of many extant lateral leaflet specimens of this genus). The leaf is 2.6 cm long and 2.5 cm wide, L:W ratio of 1:1. The base is obtuse and decurrent. The apex is incomplete, but indications are that it was rounded. Margins are sinuous. No glands are visible, indicating that the fossil is displaying the abaxial surface of the leaf (glands are typical on the adaxial side of P. trifoliata ). Primary venation is pinnate. Irregularly spaced secondary venation appears mixed; some secondaries are brochidodromous, whereas others are cladodromous. Secondaries also display both excurrent and decurrent departures from the midrib. Tertiary, quaternary, and quinternary veins are irregular reticulate. A fimbrial, perimarginal vein is present.

Site occurrence. Perdido Park.

Remarks. Ptelea is currently represented by three species in North America. Ptelea aptera and P. crenulata occur in California. Ptelea trifoliata occurs over a large portion of North America from Connecticut to central peninsular Florida, westward to Texas and parts of Mexico, northward to southern Ontario through Oklahoma, Arkansas, Missouri, Illinois, Indiana, and Ohio. The first reliable North American fossil records of Ptelea (based upon samaras) are from the middle Miocene of Idaho and Oregon ( Dorf, 1936; Chaney and Axelrod, 1959; Call and Dilcher, 1995).

Figures

FIGURE 7. Representatives Rosaceae (continued), Salicaceae, Rutaceae, and Sapindaceae from the Citronelle Formation. 1. Extant Crataegus floridana from USAM herbarium for comparison with Figure 6. 7, scale bar equals 5 mm. 2. Rubus sp. leaf (UF 19413–062083), scale bar equals 5 mm. 3. Ptelea cf. trifoliata leaf (UF 19210– 062084), scale bar equals 5 mm. 4. Salix sp. leaf (UF 19210–062085), scale bar equals 1 cm. 5. Close-up of Figure 7.4 Salix leaf margin showing salicoid teeth, scale bar equals 2.5 mm. 6. Acer cf. rubrum basal portion of leaf (UF 19210–062087), scale bar equals 1 cm. 7. Acer cf. rubrum leaf (UF 19210–062086), scale bar equals 1 cm. 8. Extant Acer rubrum USAM herbarium for comparison with Figure 7.6–7, scale bar equals 1 cm.