469 
the Monocotyledonous Leaf. 
their petioles play a part of considerable importance. The axis being sub¬ 
terranean, the entire work of raising the leaf lamina into the sunlight devolves 
upon the leaf-stalk, while its sheathing base often fulfils the additional 
function of protecting the younger leaves and the flower-buds in their 
passage through the soil. Salisbury 1 has recently pointed out that, among 
the plants of our English woodlands, the most specialized type of vernal 
‘ spear shoot *, by which geophytes emerge into the upper air, is confined 
to certain Ranunculaceae and to Monocotyledons. He quotes Hellebortis 
viridis , L., and Ranunculus Ficaria , L., as showing one or more sheathing 
scale-leaves (equivalent presumably to leaf-bases) enclosing and protecting 
the bud ; 2 the cells at the apex of the scale are strengthened by thick cell- 
walls. These examples indicate the value which a reduced leaf may have in 
the economy of a geophyte. It is probable, in addition, that a system of 
firm, phyllodic, foliage leaves, with no delicate laminae to injure, might form 
a bud which would be able to pierce the soil with special ease. There is 
obviously no necessary connexion between geophytism and a phyllodic type 
of leaf, since there are a vast number of well-established Dicotyledonous 
geophytes whose leaves have fully-developed laminae ; at the same time, 
a phyllodic leaf might well be a considerable asset to a plant in adopting 
a geophytic mode of life. 
3. The relation of the 4 Phyllode Theory’ to the theory of 
the aquatic origin of Monocotyledons. 
The theory that Monocotyledons owe their peculiar characters to 4 self¬ 
adaptation to an aquatic habit 5 has been propounded by Professor Henslow. 3 
It is not possible here to enter into the arguments for and against this view : 
the present writer can only say that it appears to her less probable than 
the solution proposed by Miss Sargant. But at the same time it maybe true 
that certain Monocotyledons adopted the water life at a very early period — 
in fact, not long after they diverged from the main stock of the Dico¬ 
tyledons. 4 The Alismataceae, whose flowers possess certain Ranalean 
features, are probably a case in point. The possible advantage of a narrow, 
linear leaf to submerged plants, especially to those growing in rapidly- 
moving water, has been frequently emphasized. It is thus clear that the 
phyllodic type of leaf is one that can accommodate itself to aquatic life 
with special ease. This may have been one of the fact.ors concerned in 
establishing the numerous aquatic Families found among Monocotyledons. 
It may well be that the phyllode theory, if accepted, will be claimed 
by those who adhere to Professor Henslow’s view regarding the aquatic 
origin of Monocotyledons, as affording support to that hypothesis; for the 
1 Salisbury, E. J. (1916). 
2 See Fig. 4, p. 474 of the present paper, for scale-leaves of Ranunculus Ficaria. 
3 Henslow, G. (1893 and 1911). 4 Sargant, E. (1908). 
