OF CEYLON AND INDIA. 
time the original growing point at the apex of the stem 
becomes replaced by three or more, as in figure 17, which 
has three, and as time goes on there may be a large number of 
growing points present. The branches thus formed, how- 
ever, never elongate, and the stem always remains as a simple 
axis, crowned by a tuft of leaves. 
The first formed leaves are very small, not more as a rule 
than 5-10 mm. long. As the stem grows the successive new 
leaves are larger and larger, till the last formed ones may 
reach 10 cm. in length and 1 mm. in diameter. The leaves 
are hairy on the upper side, as in other species of this genus, 
and exactly resemble those borne on the endogenous shoots 
of the thallus, to be described below. They are perfectly 
simple, long, and very narrow, flat or slightly hollow on the 
upper side, convex upon the lower, needle-shaped with very 
acute apex, and slightly sheathing at the base. 
In transverse section the structure agrees with that 
described by Warming (Dicræa apicata, 42, IV., p. 155, and 
fig. 24). The leaf has a small vascular bundle in the centre, 
apparently consisting only of phloem tissue. 
It is worthy of note that though the primary axis of 
the plant in this species thus becomes of considerable 
importance, more so than in most of the other species that 
have been studied, it still consists, throughout its life, 
practically only of the hypocotyl. The appearance of the 
primary axis when fully grown is shown by PI. XXXIV., 
fig. 4, which is a modified reproduction of the original 
drawing of Podostemon Gardner!, Harvey. 
These leafy primary shoots are the most important 
assimilatory organs of the plant up to the end of August or 
September, when the thallus begins to be very large (PI. 
XXXV. shows an entire plant at this stage). About this 
time they usually begin to suffer from the water pressure, 
and from the accumulation of rubbish which usually clings 
to them, and they often get broken off or flattened down 
upon the surface of the rock or the thallus, and the leaves 
tend to break off. When bent down they frequently become 
