32 VARIATION IN ASTER 
Glandular hair is most developed in A. rosczdus, where it makes 
the young growth, in case of vigorous plants, clammy to the touch, 
sometimes under the lens appearing gemmed as with little drops 
of dew over all surfaces of stem, leaf and bract; from the top of 
a plant four feet high in June completely to the ground, with ex- 
ception of the older radical leaves which by that time have lost 
much of the secretion. A 
In diminishing order, the glandular secretion is also abundant 
in the G/andulosi, and in A. commixtus, A. spectabilis, A. Herveyi, 
A. tanthinus, A. uniformis; and then follow the other Macro- 
phyla. 
Perhaps a minimum of glandular development is that of A. 
gremialis and of A. excelsior, in which it is sometimes confined to 
the backs of the lower broader bracts. In A. multiformis, A. 
nobilis, etc., it extends over the pedicels; in A. securiformis over 
the whole inflorescence ; in A. biformis also over the upper part of 
the stem; in A. macrophyllus well down the stem; in A. deca- 
phyllus and A. Herveyi nearly to the base; in A. violaris and 
A. tanthinus to the very base. 
Similar glands may occur also on the petioles: along their 
outer surfaces, as in A. zanthinus ; or only in their channeled upper 
surfaces, as in A. multiformis and many others; or only where 
that channel is continued into the midrib of the leaf, as in A. 
biformis, etc. 
The glands may occur also over the lower surface of the leaves 
as in A. zanthinus, A. uniformis, and many of the Ianthine subsec- 
tions; or over both surfaces, as in A. roscidus. 
Where the glands occur they may be so thickly placed as to 
conceal the stem, as in A. roscidus ; or may be so thinly scattered 
as to average one for each areola formed by the veinlets of the 
leaf, as often in A. zostemma. 
Typical glandular hairs, as in A. macrophyllus, may be short, 
stiff hairs tipped with a large globular gland, and standing out 
straight, at right angles to the stem. In 4. biformis and the Ian- 
thine asters the gland is usually but little broader than its stub or 
stalk. In A. securiformis and others it is almost sessile. In most, 
the gland is darker than its stalk and when well developed shows 
the dark color to be a violet which is often almost black, and seems 
