DURING THE SUMMER OF IQOI 339 
forms me that there are no authentic specimens of the former in 
the Gray Herbarium from farther south than North Carolina. 
The two species are very closely related, differing perhaps in 
habitat as much asin any other way. S. dodecandra seems to be 
mostly a maritime plant, while the usual home of S. foliosa is in 
_ creek and river swamps. 5S. fo/iosa seems to represent one ex- 
treme of the dodecandra group, of which S. decandra is the other. 
ASCLEPIAS HUMISTRATA Walt. (A. amplexicaulis Michx., not J. E. 
Smith) 
Grows sparingly in dry pine-barrens and on sand-hills in Bul- 
loch County (no. 833, June 10), also seen in Effingham and Stew- 
art counties, always on the Columbia formation. This is another 
species which seems never to have been completely described. 
Its glaucous fleshy leaves are so twisted at their points of insertion 
on the decumbent branches that they lie in vertical planes, giving 
the plant a very different appearance from any of its Eastern rela- 
tives, if not from all other species of the genus. The leaves are 
practically alike on both surfaces, and their vertical position is of 
course an example of a well-known adaptation for protection 
against excessive transpiration. The phyllotaxy of this species is 
also peculiar, the successive pairs of leaves being not decussate 
but parallel, analogous to the case of Aaptisia perfoliata already 
mentioned. 
‘Asclepias rubra laurifolia (Michx.) 
A. laurifolia Michx. Fl. Bor. Am. 1: 117. 1803. 
Differs from A. rubra L., in the shape of the leaves, which are 
lanceolate from a cordate or somewhat hastate subsessile base, 
tapering uniformly to the apex, or the upper ones narrowed at the 
base. 
Collected in low grounds near Muckalee Creek, Americus, 
July 29 (no. 1128). Accompanied by A. lanceolata Walt. (no. 
1127), which it much resembles. Also found in former years in 
several similar localities within a few miles of Americus, but 
apparently quite rare, as I have never seei more than two or three 
individuals at one time. 
Asclepias laurifolia Michx, has usually been regarded as 
identical with A. rvdra L., but my specimens and others which I 
