Fagus grandifolia Ehrhart, 1788

Elliott, Sara J., Grettenberger, Christen L., Donovan, Michael P., Wilf, Peter, Walter, Robert C. & Merritts, Dorothy J., 2016, Riparian and valley-margin hardwood species of pre-colonial Piedmont forests: A preliminary study of subfossil leaves from White Clay Creek, southeastern Pennsylvania, USA, Palaeontologia Electronica 13 (16), pp. 1-26 : 8

Fagus grandifolia Ehrhart, 1788

Figure 4

Material. EMS 425003, EMS 425004 ( Figure 4.1- 3, 4.7 ), EMS 425005 ( Figure 4.5 ).

Description. Lamina elliptic, unlobed, medially symmetrical. Primary venation pinnate. Major secondary veins craspedodromous, attachment to midvein excurrent, spacing regular. Intercostal tertiary veins opposite percurrent, sinuous or occasionally concave, acute to the midvein, angle consistent. Epimedial tertiary veins opposite percurrent, proximal course perpendicular to midvein, distal course parallel to intercostal tertiaries. Quaternary vein fabric mixed percurrent. Areolation moderately developed. Tooth spacing not visible. Distal tooth flank concave; proximal tooth flank flexuous; sinus rounded. Principal vein present. Surface puberulent; trichomes unicellular simple and solitary, with higher densities along major veins and at vein junctions.

Discussion. Observed features that are characteristic of Fagus grandifolia (American Beech) leaves include: regularly spaced secondary veins and opposite-percurrent, low-gauge tertiary veins ( Figure 4.1, 4.2 ); teeth with slightly rounded apices and rounded sinuses that occur approximately once per secondary vein ( Figure 4.5 ); and unicellular, simple, solitary trichomes concentrated along major veins and vein junctions ( Figure 4.3, 4.4, 4.7 ). The subfossils appear similar to other Pennsylvania species of Fagaceae , including Quercus muhlenbergii (Chinkapin Oak) and Castanea dentata (Chestnut) , but they are distinguishable from trichome types and tooth morphology. The leaf surface of C. dentata generally lacks the simple trichomes seen in F. grandifolia , and it instead may possess fasciculate trichomes not seen in the latter ( Hardin and Johnson, 1985). Additionally, leaves of F. grandifolia lack the incurved teeth of Q. muhlenbergii (Rhoads and Block, 2007) .

American Beech is native to eastern North America, ranging from Texas, Oklahoma, and Minnesota, east to the Florida panhandle, and north to Quebec, with isolated populations in Utah ( United States Department of Agriculture, 2011). Adult individuals typically measure 20-24 m in height ( Coladonato, 1991) and frequently reproduce asexually, forming patches or colonies (Rhoads and Block, 2007). The species is considered to be facultative-upland, but it also grows well in valley-bottoms, generally in moist soils ( Coladonato, 1991; Rhoads and Block, 2007; United States Department of Agriculture, 2011).

Figures

FIGURE 4. Fagus grandifolia (American Beech). 1, Leaf fragment, showing regularly spaced secondary veins, EMS 425004; 2, Detail of venation on EMS 425004; 3, Trichomes at vein junction, EMS 425004; 4, Trichomes at the vein junction of a modern F. grandifolia leaf from York County, Pennsylvania (collection Y1.2 of Wilf, 1997); 5, Rounded tooth on subfossil, EMS 425005; 6, Tooth and rounded sinus on modern F. grandifolia leaf from York County, Pennsylvania (collection Y1.2 of Wilf, 1997); 7, Trichome, EMS 425004.