404 ABOUT THE OAKS OF THE UNITED STATES. 
gular scales of macrocarpa. Another specimen, much nearer macrocarpa, was studied by E. Hall, a number of years 
ago, in central Illinois (Amer. Ent. & Bot. 1870, p. 191). The leaves are those of the latter species ; the bark, the 
down of the young leaf and inflorescence, and the acorn, more that of alba ; while the deep cup, coy ang half the 
acorn, is that of a small-fruited macrocarpa, but entirely destitute of a fringe ; its acorns develop much slower than 
those of macrocarpa, and more conform to alba. Of the allied oaks, macrocarpa, alba and stellata, the first develops its 
acorns soonest and the last latest ; these last are not larger than peas by the end of August, when those of alba are 
nearly full grown. 
. ALBA X STELLATA. A specimen from the same aces observer (Bebb, No, 24) must, I ga: [399 (15) ] 
be referred here. Leaves similar to those of alba, with the narrow lobes occasionally widened forward a 
retuse, after the manner of stel/ata, pubescent on the under ae as well as petioles, branchlets, and neue cups ; cup 
scales distinct and regular but considerably tumefied at base ; in alba these scales are almost entirely changed into very 
prominent knobs with short obtuse membranaceous tips ; in stellata they are lanceolate, very distinct, only slightly 
tumefied, and more canescent. Bark and flowers of Mr. Bebb’s tree are unknown to me 
imens from South Carolina, sent by Dr. Mellichamp, mentioned p. 389, seem to indicate other hybrid forms 
of the same parents. One has the leaves and furrowed bark of stellata, but the glabrous branchlets and glabrou 
anthers of alba. The other’s bark is flaky like that of alba; the branchlets, the sinuate or obtusely-lobed leaves, ie 
young acorns, are glabrous ; anthers unknown. Of niin have I seen the fruit. 
Q. ALBA X P. s. A single tree, now unfortunately destroyed, was observed by Dr. G. Vasey near Washing- 
ton, Bark “ ae pe darker than in alba ;” leaves incised-serrate, of firm texture, glossy above, pale and slightly 
pubescent beneath ; hemispherical cups with distinct tumid scales terminating in triangular membranaceous tips. The 
leaves are more those of Prinus than alba, the acorns belong rather to the latter. Both supposed parents grew with 
it on a gravelly hillside. 
The hybrid black-oaks are much more numerous, or, to speak more correctly, more have thus 
far been noticed, perhaps because their leaf-forms are more various, and thus the intermediate ones 
are more easily recognized. The mixture of entire-leaved with lobe-leaved forms would of course 
be most readily discovered from the intermediate leaf-form of the illegitimate offspring; but it 
remains for further close examination to ascertain whether lobe-leaved species do not hybridize 
among themselves as well, or entire-leaved forms also mix together, producing offspring of less 
strikingly marked characteristics. 
That we have to look for one of the parents of three of our hybrids to one and the same species, 
seems to correspond well with other observations, all pointing to the fact that some species of a 
genus are more prone to hybridize than others. This is true of Verbena, hybrids of which abound 
in this neighborhood in numerous forms as well as in a great many individuals; of most of them 
V. stricta appears to be one of the parents, perhaps because one of the most common species, or 
from some innate quality which makes it mix more readily with others; perhaps from 
a peculiar structure of the flower which may promote insect agency. Ou hybrid Ver- [400 (16) ] 
benas differ from the hybrid oaks in having almost always abortive anthers and in 
bearing scarcely any fertile seeds, while at the same time they are so common that evidently they 
are readily produced anew. 
Our black-oak hybrids are the following : — 
Probable Parents. Name under which described. Habitat. 
Q. Catesbei, aquatica, sinuata, South Carolina. 
Q. Catesbei, laurifolia, South Carolina. 
Q. imbricaria, nigra, tridentata, Tllinois. 
Q. imbricaria, palustris, Missouri. 
Q. imbricaria, coccinea, Leana, Ohio to Missouri and near Washington. 
Q. Phellos, coccinea, heterophylla, N. Jersey and Delaware. 
Q. ilicifolia, COCCINEMy Massachusetts, 
Q. CaTesBar X aquatica. Q. sryvata, Walt. Car. 235, DC. 1. c. 74. It is quite probable that in the tree ob- 
served by Dr. nanuaag i several years since, near Bluffton, S. C., we meet with Walter's obscure and long ignored 
species. Mr. Ravenel has also observed a similar form in South Cucina, and indicated cinerea as one of the parents. 
Dr. Ms tree grows on a sandy ridge with Catesbei, falcata and virens ; aquatica and the rarer cinereu are not far off. 
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