Fraxinus 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 : 16

Fraxinus sp.

Fruit

Figure 5.5

Description. A small (9.7 mm long, 4.1 mm wide) Fraxinus samara has been recovered from the Lambert Station site. A small part of the apical portion of the wing is missing. The fruit body is flattened, centrally positioned within the samara, and ~ 6.5 mm long. It is too fragmentary for meaningful specific comparisons.

Site occurrence. Lambert Station.

Remarks. Twenty native species of Fraxinus occur in North America, but only five of these ( F. americana , F. caroliniana , F. pennsylvanica , F. profunda , and F. quadrangulata ) occur in the southeastern United States. The earliest record of Fraxinus in North America is from the early Eocene of the west, and records continue into the middle Eocene Green River and Quilchana floras ( Brown, 1940; MacGinitie, 1941; Matthews and Brooke, 1971). Middle Eocene records of Fraxinus fruits have been documented in Tennessee ( Berry, 1916b; Call and Dilcher, 1992).

Leaflets

Figure 6.1–6.2

Description. Two ovate leaflets of Fraxinus are recognized in recent collections from the Citronelle Formation flora. One is probably a terminal leaflet, as indicated by petiolule length (2.2 cm). The most complete leaf is 9 cm long and 3.5 cm wide (L:W ~ 2.5:1). Margins are unlobed, crenate/serrate. Leaflet bases are decurrent, acute, asymmetrical. Apices are acuminate, one with a drip tip. Primary venation framework is pinnate. Secondary venation is festooned semicraspedodromous. Secondary veins are decurrent, irregularly spaced, with inconsistent angles. A few intersecondaries are present. Tertiary veins are irregular reticulate, as are the fourth and fifth order veins ( Figure 6.2 ). One order of teeth is present, straight or concave distally and convex proximally, between-teeth sinuses are angular to rounded. The course of the principal tooth vein terminates at the nadir of the super-adjacent sinus, consistent with several extant species of Fraxinus .

Site Occurrence. Scarborough School and Perdido Park.

Remarks. A poorly preserved leaflet attributed Fraxinus sp. was reported from the Lambert Station site by Berry (1916a), but this determination is uncertain and the specimen was not observed in the NMNH collections.

Figures

FIGURE 5. Representative Magnoliaceae and Oleaceae from the Citronelle Formation. 1. Liriodendron cf. tulipifera partial leaf (UF 19315–062075), scale bar equals 1 cm. 2. Close-up of Figure 5.1 Liriodendron leaf basal portion showing simple agrophic veins at arrows, scale bar equals 5 mm. 3. Magnolia cf. virginiana leaf (UF 19210–062076), scale bar equals 1 cm. 4. Close-up of Figure 5.3 Magnolia leaf showing details of fourth and fifth order veins, scale bar equals 5 mm. 5. Fraxinus sp. fruit (UF 19413–062077), scale bar equals 5 mm.

FIGURE 6. Representative Oleaceae (continued), Platanaceae, and Roseaceae from the Citronelle Formation. 1. Fraxinus leaflet (UF 19210–062078), scale bar equals 1 cm. 2. Close-up of Figure 6.1 Fraxinus leaflet showing higher order venation, scale bar equals 5 mm. 3. Platanus occidentalis leaf (UF 19210–062079), scale bar equals 1 cm. 4. Platanus occidentalis fruit (UF 19211–062080), showing persistent style at arrow, scale bar equals 1 cm. 5. Crataegus leaf species 1 (UF19315–062081) similar to C. spatulatha, scale bar equals 5 mm. 6. Close-up of Figure 6.5 Crataegus leaf showing higher order venation, scale bar equals 2.5 mm. 7. Crataegus species #2 leaf (UF 19210–062082), wedge-shaped lamina similar to C. floridana, compare with Figure 7.1, scale bar equals 5 mm. 8. Close-up of Figure 6.7 Crataegus leaf showing higher order venation, scale bar equals 2.5 mm.