"PR et Ie ee RSEN ee ee 
Forms or HAIR 31 
PUBESCENCE 
Pubescence is increasingly developed northward, as illustrated 
in the Cordifolial groups, in some Biotian species, and many other 
plants. But in many varieties and species it seems independent 
of locality or exposure. About five different kinds of hairs occur; 
all well developed in A. macrophyllus sejunctus ; distinguished as 
follows. 
Strigose hairs or weak multicellular bristles are a common 
feature throughout most groups of asters; according to their 
length, closeness or direction they may make the surface seem 
velvety, downy, soft or merely hairy to the touch when in life, 
while the same leaf may seem when dry to be decidedly rough. 
Obvious hair, z. e., that which is observed by the naked eye, is 
much less widespread among asters than minute hair, observable 
only by lens. 
Appressed bristles scattered over leaves, especially about one 
to an areola over the upper surface, form a very characteristic 
feature of the Macrophylli ; these are usually whitish, straight and 
stiff and needle-like when dry, and point toward the apex of the 
leaf. Their number, etc., is of considerable diagnostic value. 
Ciliation is the rule with the bracts of a large part of the 
Aster species ; and in many cases with the petioles, 
An aculeus tipping each serration of the leaf-margin is a com- 
mon Aster character and its kind and direction is fully constant 
within a species. 
GLANDS 
Glandular hair, as regards its presence, form and extent, forms 
one of the most important and constant of species-characters. 
Absent from the Divaricati and Curvescentes, glands are always 
developed in the other Biotian asters, unless it be in A. mzradilts. 
It has been already noted that among Biotian as among other 
asters, glandular hair occurs with violet rays; the few species in 
which it may seem to accompany white rays are cases where the 
white is presumably a precociously-bleached violet, or where it 
is proven so by finding the earlier violet stages, as A. ferox, A. 
macrophyllus pinguifolius, and the whole group of the Ianthine 
species. 
