145 BOTANICAL GAZETTE [FEBRUARY 
is the rule. At the same time the stipes become more massive and the 
gonidiophylls become broader. 
Along the top of the formation, at two or three localities, decidedly 
unusual plants of A/aria nana have been observed. Sometimes hun- 
dreds of these are found growing together. ig. 2 shows such a plant 
placed upon the right of and beside an individual of Poste/sia palmae- 
formis which is introduced for comparison. The plant shown in jig. 2 
is but 1o™ in height, nor do plants of this form ordinarily measure 
much more than this. The general resemblance in habit to Postelsia 
1.—Plant of Alaria nana H. F. Schrader; _ natural size about 20™ in length, 
ee pn by C, J. Hibbard, 
is certainly very marked. The mid-lamina is in all such plants eroded 
to the base or but poorly developed. Under such conditions’ it is evi- 
dent that the gonidiophylls must assume the photosynthetic function, 
and they have consequently taken a broader form. One of these obo- 
vate gonidiophylls is clearly shown in the figure. Upon many of these 
gonidiophylls soral areas are either not developed or limited to the 
basal portion. The number, too, of the gonidiophylls seems to be 
increased as compared with normal plants of the lower levels. The 
stipe is quite erect, very firm, and provided with a strong growth of 
hapteres at the base. In general, the plant which has come to live 
under the conditions to which Postelsia has adapted itself receives the 
imprint of environmental forces, as did the ancestral forms of the other 
kelp, and exhibits a striking homoplasy. 
In comparing the plants shown in fg. 2, it should be remembered 
that Postelsia, a member of the Lessonia group, is essentially unilami- 
Be oe pe a 
