28 VARIATION IN ASTER 
Nature, however, which will not allow us to think herself tram- 
meled by hard and fast lines, varies sometimes in the direction of 
yellow in the rays, and without actually reaching a full yellow, they 
become decidedly yellowish in dA. viridis, A. Claytoni crispicans, 
and in other forms of A. Claytoni, A. erectus, and A. ardens. One 
very late-flowered plant of the second mentioned, gathered Novem- 
ber 8, 1896, half way up the rock-front of the Palisades, growing 
on a ledge, came quite near to clear, though pale, yellow. 
Virescence.—W hite rays often become greenish with age. All 
the Divaricati and Curvescentes seem subject to this, irrespective of 
exposure or nutrition. The degree and kind of color and the 
readiness with which it is assumed seems however to be, in many 
cases at least, a valuable distinctive character; as in the following 
white-rayed species : 
A. olivaceus, rays apt to turn early to a pale olivaceous tinge. 
A, divaricatus fontinalis, rays apt to turn cream-color and 
sometimes even yellowish. 
. Schreberi, rays apt to turn cream-color. 
curvescens, rays apt to turn cream-color very early. 
divaricatus, many forms, rays apt to turn cream-color. 
. Soctabilis, rays cream-color and soon turning olivaceous, 
slightly greenish with a little brown; universal or at least com- 
mon in this species. 
4. tenebrosus, rays sometimes like the last, but olivaceous tinge 
assumed more rarely or more slowly. 
A. castaneus, rays apt to turn cream-color. 
A. axillaris, rays apt to turn cream-color. 
Virescent rays are, as might be expected, rare. among the 
Macrophylli and other species which show any trace of blue; 
but are produced sometimes in late-flowering stages of those which 
become pale or whitish, as A. densatus, A. securiformis, and A. 
violaris ; also rarely, blended with purplish, in A. roscidus. 
Color of dis&-flowers : normally deep yellow turning to some 
shade of reddish-brown, and fading brownish. In a few varieties 
the disks are pale, not becoming a deep yellow. The shade of 
reddish-brown assumed is very characteristic and conspicuous. 
Brown predominates over red in many forms of A. divaricatus, 
including the typical form. Red predominates in many other 
i i he 
