298 WILLIS : MORPHOLOGY OF THE PODOSTEMACEÆ 
have rather thicker walls. The leaves contain chlorophyll, 
and form the chief assimilating organs of the plant. In the 
material from the Anamalais and Travancore the ramuli 
have broader leaves (PL YII., cf. figs. 15, 16). The ramnlus 
grows only for a short time, and soon reaches its full length. 
The general appearance of a plant covered with these ramuli 
is well shown in PI. V. The ramuli near the tip of the 
stem far overtop the main axis. Later in the life of the 
stem the ramuli either drop off altogether, or lose their 
leaves ; the latter case is very evident in the right-hand part 
of PI. YI. 
It is very difficult, as Warming has already pointed out, 
to determine the exact relationship of position of the ramuli 
to the leaves borne on the main stem, and I have not yet 
succeeded in satisfying myself on this point. When very 
young, the ramulus seems often to lie exactly in the axil of 
a leaf, but when older and expanded it is very commonly 
not so arranged, but frequently has a leaf a little to one side 
of itself, as in PI. YII., fig. 12. There is not as a rule a 
ramulus for every leaf. The axis of the ramulus contains a 
very slender central vascular strand. 
A little way back from the growing point, at the part 
where the ramuli have reached their full development or 
nearly so, buds may be seen in the upper angles between 
them and the main stem (PI. YII., fig. 15) ; these buds give 
rise to shoots of unlimited growth, which repeat the struc- 
ture of the main axis. Commonly many of these buds 
remain more or less dormant, until the flowering period. 
Thus at every node there may be two shoots, an upper long 
one of unlimited growth repeating the structure of the main 
axis, and a lower ramulus. By this time the leaves of the 
main axis have usually fallen away, leaving no trace, so that 
when, as often happens, the ramulus has also lost its leaves 
one is liable to mistake the two shoots for a leaf with shoot 
in its axil. In Plate Y., and still better in the left-hand part 
of PI. YI., this arrangement of the shoots can be very 
clearly seen, especially with the aid of a lens. 
