158 ILLINOIS ACADEMY OF SCIENCE 
The factor just considered, i.e., shortness of the growing 
season, appears indeed also to account in part for individual 
dwarfing of upland plants. Thus on the Biological Station 
grounds one frequently finds growing side by side normal size 
and extremely dwarf forms of the same species. Plants which 
are noteworthy in this respect are the Shepherd’s purse, Cap- 
sella bursa pastoris L., Peppergrass, Lepidium virgimcum L., 
and the Golden Corydalis Capnoides aureum (Willd.) Kuntze. 
The Peppergrass and the Shepherd’s Purse flower and fruit 
throughout the entire summer, The seedlings of some of the 
earlier maturing pods germinate early in autumn, and form 
stout conspicuous rosettes. which winter over in this form and 
in spring spring up into tall, robust plants. Seeds from the 
later maturing pods do not germinate however until spring, 
and appears as a rule to form short-season, comparatively 
puny plants. In Golden Corydalis, the individual plants have 
an exceedingly long period of bloom, from early spring until 
midsummer and one finds ripened pods and unopened flower- 
buds on the same plant. The seeds from early-ripening pods 
germinate in early autumn to form rosettes while those from 
the later ripening pods do not germinate until spring, when 
they frequently form puny plants, with 1 or 2 leaves and a 
blossom. 
Still, shortness of season cannot entirely account for dwarf- 
ness and early ripening. We know that while late planted corn 
will mature more rapidly than the same variety planted earlier, 
that there is a fixed limit which cannot be trespassed, and the 
farmer who would plant his seed at date of germination of our 
water plants mentioned in the earlier part of our discussion, 
would reap—not dwarf corn, but would find his crop cut down 
by frost when still green and immature. Among land plants 
moreover, we have dwarf perennials, such as dimunitive wild 
crabs, cedars, hackberry, etc., where the length of the growing 
season can cut no figure; and we know that the seedling of a 
large seed produced by the underground cleistogamous flower 
of the hog-peanut is a veritable giant compared with the frail 
“spindling”’ brother from the small aerial seed. 
The case of dwarfing, frequently individual, among upland 
plants, appears on the whole to be a complex and diversified 
problem, assignable to numerous causes. The case of dwarf- 
