Liriodendron cf. tulipifera 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 : 14

Liriodendron cf. tulipifera Linnaeus, 1753

Figure 5.1 – 5.2

Description. One partial leaf with marginal petiole attachment is identified as Liriodendron , probably L. tulipifera . A portion of the slender petiole (approximately 1 mm thick) is 1.1 cm in length, but was probably originally much longer. The original leaf was> 6.8 cm long and> 6.8 cm wide, and broadly concavo-convex with an obtuse base. Primary venation is pinnate. Simple agrophic veins form loops near the basal portion of the leaf ( Figure 5.2 ). Proximal secondary veins are decurrent and arching. Thickened secondary veins are irregularly spaced with consistent 45° angles. Some intersecondaries are present. It is difficult to categorize the looping tertiaries; some appear percurrent, whereas others appear irregular, reticulate. However, the fourth order veins are clearly irregular, reticulate. A fimbrial vein is present. Unfortunately, the characteristic notched apex of the genus is not preserved on the fossil.

Site occurrence. Scarborough School.

Remarks. Liriodendron tulipifera occurs in woodlands and wetlands extending from southern Alabama and the Florida panhandle to Louisiana, northward to Illinois, Michigan, and Vermont. Populations common on the southeastern coastal plain typically have smaller leaves, shorter petioles, rounder lobes, and rounder bases than typical leaves of more northern populations ( Godfrey, 1988; personal observation). The Citronelle Formation specimen is most similar to the extant southeastern variety in the observable features. Leaves and fruits of Liriodendron occur in the Miocene of Idaho ( Baghai, 1988). The two extant Liriodendron species (the other being L. chinense ) probably diverged in the middle Miocene ( Parks and Wendel, 1990; Azuma et al., 2001; Nie et al., 2008).

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.