114 FLORA OF WASHINGTON AND VICINITY. 



+ Quercus Phellos. L. Willow-Oak. 



Secoucl week in May; fruit, first of October. 



Quercus Leana, Nutt. Lea's Oak. 



Carroll Estate. [See Field and Forest, October and November, 1875, p. 39; also. 

 Botanical Gazette, October, 1880, p. 123.] First week in May; fruit, last half of Sep- 

 tember. 



Quercus heterophylla, Micbx. Bartram's Oak. 



A number of young trees not bearing fruit, but having leaves closely resembling 

 tbosp of the authentic specimens, have been found. Near Fort Bennett, Va. (Dr. 

 Foreman); High Island (this tree was quite large, and would probably have soon 

 borne fruit, but it was unfortunately girdled); Terra Cotta Swamp (this specimen 

 is ■now under close surveillance). 



t Castanea pumila, Mill. Chinquapin. 

 Second week in June ; fruit, October. 



t Castanea vulgaris. Lam., var. Americana, A. DC Chestnut. 

 First half of June ; fruit, October. 



tragus ferruginea, Ait. Beech. 

 Last of April; fruit, July. 



SALICACE-ffi. 



Willow Family. 



Salix nigra, Marshall. Black Willow. 



First week in May. 



Salix nigra, Marshall, var. falcata, Carey. 

 Eastern Branch. 



Salix nigra, Marshall, var. Wardi, Bebb. n. v. 



A remarkable form, with the broad leaves much whitened underneath, larger 

 stipules, &c., approaching in appearance S. cordata, with which it grows. This 

 peculiar willow has interested me for many years, as I was unable to harmonize its 

 characters with any description or to find its exact counterpart in any collection. 

 Still it was not until the spring of 1880 that I made any special effort to solve the 

 difficulty. I then sent it to Professor Gray, who simply remarked upon it that the 

 ovaries were those of S. nigra. I subsequently sent specimens to Mr. M. S. Bebb, who 

 be(;anie at once greatly interested in the form. Upon learning that it grew with 

 both S. nigra and S. cordata, ho was at first inclined, as I was also my%elf, to regard it 

 as a hybrid resulting from the intercrossing of these two species. At his suggestion 

 I have since made the most thorough examination of the plant and the conditions 

 under which it is found, the result of which has greatly weakened the force of this 

 theory, and, judging from Mr. Bebb's careful description, which is appended, he is 

 also less couviuccd of the cross than formerly. 



The plant was first met with among the rocks on the river bottom adjacent to the 

 Chain Bridge and Little Falls, where it predominates over other forms, though S. 

 nigra is quite common there, and pistillate plants of S. cordata occur somewhat 

 sparingly, in which, in the absence of starainate plants, the ovaries rarely perfect. 

 S. miiricoidcs, which is regarded as a cross between iS. sericea and S. cordata, is also 

 present in both sexes, and here too S. longifolia is found. But in addition to this 

 locality, I have observed this variety of S. nigra as far up the river as Great Falls 



