30 VARIATION IN ASTER 
on the others. Allowing for this, there often remains a color-ten- 
dency which is specific. For instance, the stem of A. puniceus 
tends to develop a deep purplish-red ; that of A. formis also a 
purplish-red ; that of A. ebeneus, a deep red that is almost an 
ebony black ; that of A. gremialis a slfining green ; that of A. ul- 
marius, a pale brown; etc., etc. Most of the Drvaricatt show a 
greenish stem with a little brown; A. macrophyllus and kindred, 
brown with little green. 
Color of leaves. — This is quite constant throughout a species ; 
deep dull green in A. macrophyllus ; a brighter green in A. Schredert, 
A. umbelliformis, etc., apple-green in A. macrophyllus sejunctus, 
pale yellowish-green in A. mollescens, etc. A. violaris is apt to show 
a deep blue-green but is sometimes pale; A. quiescens has a still 
different tone of deep blackish-green. ; 
Autumnal leaf-color is also moderately constant; yellowish 
with some brown in A. divaricatus, A. Schreberi, A. violaris, etc., 
russet-brown in A. roscidus, and many others. Some forms tend 
strongly to marmorate or irregularly spotted leaves, or leaves vein- 
streaked with deep and lighter red; as A. rupicola. © 
Primordial leaves are apt to be strongly purpled, due to pres- 
ence of sugar compounds, especially underneath; showing the 
tendency to red common in opening maple and ash leaves. When 
primordial leaves develop green color it is commonly paler than 
in the later and higher leaves, as is to be expected from their com- 
monly shaded position. 
Etiolated leaves occur in any species when deprived of light, as 
by a board or a woodman’s chips fallen on them. A. divaricatus 
shows extreme examples. 
Dark green species among the Biotian asters are apt to be those 
of deep woodlands, as if the less light the more chlorophyll were 
developed; as in A. atrovirens, A. tenebrosus, A. quiescens, A. ros- 
cidus, A. decaphyllus. The cause invites inquiry ; for they seem 
to antagonize the other observed result of complete lack of light, 
etiolation. 
Glaucous surfaces of leaf or stem are nearly confined to A. laevis 
and relatives, and among Biotian species to A. excelsior, which has 
a somewhat glaucous stem. 
