388 BOTANICAL GAZETTE [NOVEMBER 
growing regions harmonize completely, and the inclosed bud is 
thrust forward through the soil, with no serious injury from antago- 
nistic growth forces. The pointed cylinder meets the conditions 
of progress through a solid medium as does the flat frond for floating 
upon a fluid surface. 
The Lemna frond may be closely compared to the Erythronium 
runner in structural details. If the outer scale of the terminal 
Fic. 1.—Homology of Lemna frond and Erythronium runner: a, tip of first leaf; 
b, stem apex of bud; s, shoot axis; pp, walls of pouch. 
bud of the runner could be turned forward on its base as a hinge, 
a structure would result of the character shown at II in the text 
figure. This has a terminal foliar region, a central one from which 
a dorsal bud and ventral root originate, and a basal stem or cauline 
region,® but the bud is erect. The growing regions are still at the 
base of the foliar and near the tip of the cauline portions of the 
whole. If this were to be formed within a vertically restricted 
space, the dorsal bud would be flattened, and probably somewhat 
6 These correspond respectively to the “upper internode,” the “node,” and the 
“basal internode” of CALDWELL (op. cit., p. 43), and supports his use of the word 
“shoot”; but the shoot consists of a terminal leaf, a node with bud tissues, and a 
stem, rather than of an “undifferentiated upper internode” and specially modified 
“basal and nodal regions.” 
