ECOLOGICAL SIGNIFICANCE OF EAGLE CREEK FLORA 583 



Laurus 2, Platanus 2, Liquidambar 3, Crataegus i, Slerculea i, 

 Rhus I, 7/eic 1, Acer 2,-, and Fraxinus i. 



Considering the ecological composition ot the flora, the out- 

 standing feature is the presence in it of leaves which represent two 

 distinct ecological types, one xerophytic and the other mesophytic. 

 The former includes several 

 species of oaks, notably Quercus 

 pseudo-lyrata (Fig. 2), which is 

 the most abundant species in the 

 flora. The latter comprises most 

 of the remainder of the flora, in- 

 cluding a large number of genera 

 and species, of which Acer hendirei 

 is represented by the largest num- 

 ber of specimens. 



Quercus pseudo-lyrata, the 

 most abundant species, is found 

 in twelve of eighteen localities fur- 

 nishing leaves. Clearly the con- 

 ditions under which it lived may 

 be said to be widespread. Its 

 leaves have the thickness and 

 coarse epidermis which constitute 

 the morphological expression of a xerophyte. 

 sentatives, Q. velutina, Q. muhlenhergii, and Q 

 their typical range in xerophytic habitats, 

 probable that Q. pseudo-lyrata occupied a similar habitat, an 

 exposed situation with a small amount of moisture. 



Associated with this presumably xerophytic species, commonly 

 in the same slab and almost invariably in the same locality, is Acer 

 hendirei (Fig. 3) , a maple closely related to A . macro phyllum, which 

 is an abundant member of the flora now living in the gorge. Even 

 were it not well known that maples are almost exclusively found in 

 well- watered habitats, the mesophytic character of Acer hendirei 

 could be ascertained from the thin texture and large size of the 

 fossil leaves. Occurring in fourteen out of eighteen localities it is 

 an abundant species and one which shows moisture requirements 

 widely different from those of Quercus pseudo-lyrata. 



Fig. 3. — Acer bcndirei. 

 natural size. 



One-half 



Its nv)dern repre- 

 marylandica, have 

 It seems entirely 



