Rubus sp.

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 : 18

Rubus sp.

Figure 7.2

Description. This description is based on part and counterpart of a leaflet, 2.3 cm long and 0.9 cm wide, elliptic, L:W ratio 2.5:1. Margin is toothed. An asymmetrically inserted petiolule is 2 mm long. The base is convex, obtuse. The apex is obtuse, round. This specimen is probably a lateral leaflet because a small sub-basal lobe is present, as has been noticed in lateral leaflets of extant R. argutus and R. cuneifolius . Primary venation is pinnate. Secondary veins are excurrent, craspedodromous, and branch very near the margin. They are irregularly spaced, depart the primary vein mid-leaf at ~ 45°, angles become much wider proximally. Tertiary venation is mixed percurrent; quaternary and quinternary veins are irregular reticulate. First order teeth are regularly spaced with angular sinuses; distally they are straight; proximally they are usually convex, but may also be straight. The occurrence of a second order of teeth is irregular. Teeth are absent near the basal portion of the leaf, as is also recognized in many leaflets of extant R. argutus and R. cuneifolius . Principal tooth veins terminate at each tooth apex.

Site occurrence. Lambert Station.

Remarks. Rubus is a large genus that is well represented in North America today with ~ 237 species, 23 of which occur in the southeastern United States. As for Crataegus , fossils similar to Rubus occur in the early and middle Eocene Okanogan Highlands of eastern Washington, USA, and British Columbia, Canada. Rubus leaflets have been identified from the western Succor Creek flora ( Smiley and Rember, 1985; Fields, 1996).

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.