Carya 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 : 10

Carya sp.

Fruits and catkins

Figure 2.9–2.11

Description. Several Carya fruit specimens have been found, but are not very informative. However, one displays a pericarp approximately 2 mm thick ( Figure 2.9 ), which is thicker than the pericarp of typical C. aquatica , a common leaflet type in the flora. A husk of another fruit that is at least 3 mm thick suggests the presence of a second species of Carya where the husk splits apart from the rest of the fruit, such as in extant C. tomentosa or C. myristicaeformis . Carya catkins with in situ pollen are also common at most sites ( Figure 2.10 –11). Although they cannot be identified to species, they underscore the prominence of Carya in the Citronelle flora.

Site occurrence. Scarborough School.

Remarks. Berry (1916a) assigned the Carya nuts (and leaflets) in the original collection from the Lambert Station site to a new species, “Hicoria” pretexana, indicating close affinity or ancestral status to the extant species Carya texana , but there is no clear justification for this specific assignment. Carya fruits from the late Miocene to earliest Pliocene of Tennessee were recently assigned to a new fossil species, C. tenneseensis , with possible affinities with the European fossil C. ventricosa ( Huang et al., 2014) . Unfortunately, the Citronelle Formation fruits provide few points of comparison with this and other fossil or extant Carya fruits due to preservational limitations beyond that presented above.

Leaflets (general description). All Carya leaflet specimens from the Citronelle Formation share the general characteristics of the genus. Leaf margins are generally toothed. Bases are often asymmetrical, although some are symmetrical. Primary venation is pinnate. Secondary veins are semicraspedodromous with angles increasing from apex to base. Tertiary veins are percurrent. Leaflet variability within the assemblage indicates that at least three species of Carya are represented, which are described separately below.

Figures

FIGURE 2. Representative Aquifoliaceae through Juglandaceae from the Citronelle Formation. 1. Ilex sp. leaf (UF 19210–062063), scale bar equals 5 mm. 2. Clethra cf. alnifolia (UF 19210–062064) partial leaf, arrow indicates mucronate tooth apex, scale bar equals 5 mm. 3. Close-up of Figure 2.2 Clethra leaf, note mixed-percurrent tertiaries, scale bar equals 2.5 mm. 4. Extant Clethra alnifolia leaf from USAM herbarium for comparison with Figure 2.2, scale bar equals 5 mm. 5. Gaylussacia sp. leaf (UF 19315–062065), scale bar equals 5 mm. 6. Extant Gaylussacia sp. from USAM herbarium for comparison with Figure 2.5, scale bar equals 5 mm. 7. Vaccinium sp. leaf (UF 19315–062066), scale bar equals 5 mm. 8. Close-up of Vaccinium leaf margin from Figure 2.7 showing teeth, scale bar equals 2.5 mm. 9. Carya fruit (UF 19315 – 062068), scale bar equals 5 mm. 10. Carya sp. catkin with in situ pollen (UF 19315 – 062067), scale bar equals 5 mm. 11. Carya sp. pollen tetrad from specimen in Figure 2.10, scale bar equals 10 µm.