ABOUT THE OAKS OF THE UNITED STATES. 407 
Several forms of oaks have at one time or another been considered as hybrids which most prob- 
ably are varieties or sports of one or the other of the well-established species. 
Q. oLIV&£FoRMIS, Michz., is a variety of macrocarpa with elongated acorns in a deep and narrow cup, and not a 
hybrid of vasa ae with alba, as has been suggested. 
Q. RUNCINATA* was the name given to a form I found in tke richest Mississippi bottom-lands opposite St. 
Louis, together with rubra, imbricaria, and palustris. From its smaller and narrower, coarsely dentate, not lobed 
leaves, and its smaller fruit, it seemed distinct enough from rubra, and was possibly a hybrid of it and some other small- 
fruited allied oak. But the leaves of rubra are so variable in size and outline that DeCandolle (1. c. 60) was right in 
seat © a variety of rubra. 
CATA., var. subintegra, is a variety of falcata which I had taken for a hybrid of that species and cinerea. 
Dr. Mellichamp death it from South Carolina and Mr. Canby from Maryland. It seems to be only a strange sport of 
falcata itself, an extreme state of var. triloba, with trilobed as well as entire leaves. The glandular pubescence of the 
young and the smoothish, not reticulated, upper surface of the mature leaf are those of the species. Fruit not seen. 
Q. QUINQUELOBA I named a form of nigra with 5-lobed leaves, which I found on the hills of St. Louis, and at 
one time considered as a cross between nigra and tinctoria ; DeCandolle (1. ¢. 64) places it correctly with 
nigra. It is not even a variety, but rather a juvenile state which had become permanent in rege a [543 (21) ] 
young trees or shoots of nigra have sinuate-dentate or many-lobed leaves, but in fertile ones the leav 
almost always more or less 3-lobed or 3-dentate at the much-widened a I have since seen a see which on 
one fruit-bearing branch had only the leaves of quinqueloba, while all the eres branches had the regular cuneate 
3-dentate nigra leaves. The same form occurs near Washington (ZL. F. Ward, in “ Field and Forest,” October, 1875, 
where several other real or supposed hybrids are enumerated, which call for further careful investigation in loco). 
New material having come to hand since the above was in type, I have to add some further remarks. 
The typical Q. palustris has globose or depressed acorns, but near St. Louis it is occasionally seen with oblong or 
even elongated acorns. A specimen of Q. Texana,t Buckley, sent by the author to the Agricultural Department, 
ores is evidently this form of palustris, though it is said to grow near Austin “on hills.” 
e394. Another abnormal type, which I cannot but refer to rubra, has been sent from the bottom lands of 
the Gonaste and Blanco rivers, affluents of the Guadalupe, Texas, by Lindheimer and Wright. The leaves have the 
cut of coccinea ; the large (1 inch long by less than % wide) oblouke acorns are borne in hemispherical slightly turbinate 
cups, covered by small appressed, smoothish scales. The bark of the tree is “ pale and smoothish, much like that of 
cused In many respects the tree seems to be intermediate between rubra and coccinea, an “ ambiguous ” form. 
Q. c EA: numerous specimens, fresh ones from this neighborhood, and dried ones with mature fruit from 
different Vecidiiies have weakened my hope of distinguishing tinctoria from the typical coccinea. The yellowish-canes- 
cent, squarrose cup-scales are found in all the forms of this region, but northward as well as eastward on do not seem 
to be so characteristic of the species ; there they are often smaller, more appressed, and less canescent ; and this may 
be the form which Michaux has figured as his coccinea, while his tinctoria has larger and paler scales. We may, then, 
distinguish the following varieties : 1. Large winter buds, leaves with broader undivided lobes, cup-scales squarrose, 
acorns oblong or globose. 2. Small winter buds ; leaves with slender, deeply cut, divaricate lobes, cup-scales and 
acorns as in 1. 3. Buds and leaves as in 2; cup-scales smaller, more glabrate, appressed ; acorns more ceased 
ovoid. The first may be Bartram’s Q, tinctoria, the third the true coccinea, and the second an intermediate form 
The third variety closely approaches what I have considered as the form ambigua of Q. rubra. 
The Oaks of Wheeler’s Expedition (Report, Botany, 1878, pp. 249-251), and of the Botany 
of California, 1880, II. 93-99, are by Engelmann, but no new species are included. 
In the former paper (p. 251), it is said of Q. Emoryi, Torrey : “ Botanically a most interesting species, as it com- 
bines many characters of the white-oaks, viz, the annual maturation and especially the position of the abortive ovules 
at the base of the nut, with characters of the black-oaks, viz., the black bark and coarse wood, the small number and 
large size of the stamens, the long, recurved styles, and the tomentose inner coating of the shell ; the leaves show, as 
they do in many black-oaks, a stronger reticulation on the upper than on the lowrde side.” In the latter sarong 
(p. 97) Q. chrysolepis, var. Palmeri, Engelm., is raised to specific rank, under the name Q. Palmeri, Engelm. — E 
* Gray's Manual, 5 ed., 1868, p. 454. — 
t In a note in the Botanical Gazette, ie 0 vii. 14, Dr. Engelmann a states that ‘‘ Buckley’s Quercus Texana 
is undoubtedly correctly placed by him with the polymorphous Q. rubra. 
