38 VARIATION IN ASTER 
leaves of the stem are generally those which yield the most char- 
acteristic teeth. See figure showing forms, under Terminology. 
TEXTURE 
Leaf-texture is highly characteristic usually ; the variations are 
noted in the following descriptions ; thickness and thinness may 
either of them be accompanied by great roughness or smooth- 
ness. The thick leaf may be either flabby (4. macrophyllus, A. 
quiescens) or firm (A. violaris) or coriaceous in substance. The 
thinnest large leaves are perhaps those of A. oviformis, about 
6-7 x 4 inches; the thickest perhaps in A. macrophyllus, the 
most coriaceous in oval radicals of A. roscidus. Biotian leaves 
which are smooth, firm and thickish nevertheless always come 
short of the peculiar smooth feel of A. spectabilis (approaching it 
nearest in A. Herveyt) and fall still farther short of the cool 
smoothness of A. /aevis (except in a few sports or hybrids). 
Texture is sometimes a notable feature of the petioles also; 
crisp brittle subsucculent petioles occur in A. carmesinus ; limp 
watery petioles (equally succulent) in A. Amicola ; stiff straight 
petioles, as in forms of A. macrophyllus, etc. 
Roughness of upper surface is usually increasingly developed in 
sun. It is chiefly due to increased number or greater thickening 
or hardening of the bristles normally present (A. macrophyllus) ; 
or may be due to development of minute hard projections, or the 
formation of a callus on each areola (granular roughening, in 
A. macrophyllus pinguifolius, etc.) ; or even to stout minute spines 
set closely over the whole upper surface (A. mirabilis). It may be 
uniform over the leaf (A. macrophyllus commonly) or confined to a 
marginal zone leaving the center smoothish (A. Schredberi often), as 
noted by Nees, Gen. Ast. 1832, and habitually designated by him 
as scaber ad margines. 
This is a very different thing from the line of bristles or hairs 
which forms a marginal ciliation upon most Biotian leaves, which 
projects horizontally from the exact edge, lies in the plane of the 
leaf, and is usually much rougher than the feebler bristles of the 
upper surface just described. 
Roughness may be developed in drying on a leaf which was 
smooth in life; and in A. macrophyllus pinguifolius, two parts 
