54* TRANS. ST. LOUIS ACAD. SCIENCE. 



other two species, and thus come to the conclusion that the former must be 

 the parents. 



c^. ilicifolia X coccinea, Robbins in Gray Man., ed. 5, pag. 454, dis- 

 covered by Dr. Robbins at Uxbridge, Massachusetts, in 1855, of which 

 I have seen flowering and fruiting specimens in the Cambridge Herbari- 

 um, seems just intermediate between the two parents. "Tree 40 feet high, 

 19 inches in circumference, both parents within 4 rods"; leaves 4-5^ inches 

 long, nearly 4 wide, sinuate-lobed, lobes acutate, mostly bristled-toothed 

 towards their apex; youngest ones greenish pubescent above, canescent 

 below, at maturity strongly reticulate {^ilicifolia is very slightly so) and 

 shining above, and with the branchlets lightly pubescent below; cup 

 deeper than in ilicijolia, glabrate. The persistent though light pubescence 

 resembles ilicifolia, -whWe the shapeof the leaf reminds one of raira rather 

 than coccinea. 



Several forms of oaks have at one time or another been consid- 

 ered as hybrids w^hich most probably are varieties or sports of 

 of one or the other of the well-established species. 



^. olivcBformis., Michx. is a variety of macrocarpa with elon- 

 gated acorns in a deep and narrow cup, and not a hybrid of tna- 

 crocarpa with alba^i as has been suggested. 



J^. runcinata was the name given to a form I found in the 

 richest Mississippi bottom-lands opposite St. Louis, together with 

 rubra., imbricaria., and palustris. From its smaller and nar- 

 rower, 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 considering it a variety of rubra. 



^. falcata var. subintegra is a variety oi falcata which I had 

 taken for a hybrid of that species and cinerea. Dr. Mellichamp 

 sent it from South Carolina and Mr. Canby from Maryland. It 

 seems to be nothing but a strange sport oi falcata itself, an ex- 

 treme 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 spe- 

 cies. Fruit not seen. 



J^. quinqueloba I named a form of nigra with 5-lobed leaves, 

 which I found on the hills of St. Louis, and at one time consid- 

 ered as a cross between nigra and tinctoria ; DeCandolle (1. c. 

 64) places it correctly with nigra. It is not even a variety, but 

 rather a juvenile state which had become permanent in that tree ; 



