16 BOTANICAL GAZETTE [JANUARY 
exception that dicotyledonous plants possessing anomalous embryos 
are either partially or wholly geophilous in habit, having stems 
either in the form of a rhizome, tuber, or a short, squat axis.” 
That anomalies not only in embryology and anatomy, but 
even in embryo sacs, depend largely on environmental conditions 
has been suggested in the past (JOHNSON 15), and seems continually 
to be receiving wider attention. Hutt (14), for example, has dis- 
covered in the Andes, Central America, and Mexico a few geophilous 
species of Peperomia which are of great interest. Although their 
seedlings are described as possessing all the external characters 
of monocotyledons, yet they are true dicotyledons, but the coty- 
ledons exhibit a marked division of labor, one serving for absorp- 
tion, the other for photosynthesis. That these species are true 
dicotyledons is shown by the structure of the seed; the presence 
of stomata on the lamina of the absorbent cotyledon; persistence 
of the primary root for,some time after the formation of the bulb; 
and the vascular structure: of the seedling. Moreover, most of 
the members of the genus, containing some 400 species, are nor- 
mally dicotyledonous. The peculiar habit of these few species 
is therefore interpreted as due to xerophytic conditions, resulting 
in the assumption of the geophilous habit, accompanied by forma- 
tion of bulbs or tubers, and finally affecting even the embryonic 
structure of the plants so that the division of labor referred to 
above has resulted. Although Hi~t opposes Miss SARGANT’S 
theory as to the origin of the single cotyledon of monocotyledons, 
it is worthy of note that he attributes the anomalies in Peperomia 
to the geophilous habit. This is the same cause that other workers 
have assigned for the pseudo-monocotyledonous habit, anomalous 
stem structure, and so on, in the case of various other dicotyledons. 
Now if it is conceivable that a pseudo-monocotyledonous habit 
has arisen in different ways among dicotyledons, then the possi- 
bility of the same thing happening among monocotyledons presents 
itself, especially if monocotyledons have branched off at several 
points along the dicotyledonous line. Indeed, attempts at a 
causal explanation of the origin of monocotyledons from dicoty- 
ledons have actually been made, one of the most important of 
these being HENsLow’s theory (12). 
