242 DESCRIPTION OF ASTERS; DIVARICATI 
its arcuate stems. On the flat summits of granitic and basaltic 
rocks, or more commonly springing from cracks and ledgesin the 
face of such rocks; in which case a few stems are assurgent, but 
most spread downward and radially outward from the face of the 
rock. Their neighboring outliers on the top of the same rock 
show all the same directions and also produce many erect but 
weak stems. 
Apparently modified from weak-stemmed plants of A. Claytoni 
by place of growth, but seems to have now acquired the arcuate 
habit so thoroughly as to reproduce it often where unnecessary 
or even prejudicial ; and seems to retain the weakness of stem per- 
sistently. 
Range. White Mountains to the Palisades, and probably else- 
where ; first half of September. 
Examples : 
N. ^ praeses Flume, Au. 30, '98, and Se. a ipm 
N. , Yonkers, Stony Lonesome, Se. 23, ’99; Bryn Mawr Park, Se. 
'99; Split eee r^ eb 1900, Se., 1901, Se., 1902, x 15, 1903, Se. 16, 1905; 
Seminary Corner, Se. 1905. 
MUS above Undercliff, Se. 29, '97, Se., '98, Se. 14, '99, Oc. 7, 
'99, Se. 14, 1 
Allies. Comparing other arcuate congeners, 4. camptilis has 
a more oblong and narrower leaf-type, and very much narrower 
slender bracts ; and so far as observed, is partial to banks and soil 
above shale 
A. stilettiformis is sometimes almost equally decumbent, but is 
then easily distinguished by its very conspicuously slit-serrate 
axiles. A. Parthianus lacks the breadth of leaf, sinus and bract 
which distinguish A. arcuatus. 
Variants, 
? A. arcuatus x A. aucuparius, a probable hybrid ; orbicular 
tendency strong below as if from the former parent, oval-oblong 
tendency strong above, as if from the latter; but all leaves very 
small, 16 or more being only 1% or 11% in. long; stems over 2 
ft. ; inflorescence increased and more branched. — With both sup- 
posed parents, Palisades, Se. 29, '97. 
36. Aster sociabilis sp. nov. 
Rigid-stemmed erect plants with small roughened ovate-acu- 
minate leaves, short petioles, salient teeth, deep strong sinus, 
broad lingual and diverse bracts, small high-angle or all-axillary 
