OF CEYLON AND INDIA. 
333 
when taken from the water the leaves are very slimy, like 
those of many other water plants. This particular species 
is practically free from silica, and consequently shrivels 
rapidly when taken out of the water, all but the stout erect 
stems ; the leaves fall, and the thallus withers to a thread. 
As the stems grow upwards the leaves fall off below, 
leaving well-marked scars. Up to the beginning of the high 
water of the north-east monsoon the stems (at Hakinda) are 
mostly unbranched, and the leaves monothecous (i.e., with 
sheath on the upper side only). Subsequently branching 
occurs from the lower axils of dithecous leaves (with sheaths 
on both upper and lower sides, cf. Warming), and a terminal 
flower is developed on each branch. I have, as with the 
other species, been unable to get material showing the 
development of the flower. When the water falls in Decem- 
ber the flowers may be seen fully developed in their spathes, 
the latter not, however, opening until exposed by the fall of 
the water. At this period the leaves are usually a good deal 
smaller than in the earlier part of the vegetative season. 
Except that the spathe is shorter and stouter, the general 
appearance is very like that figured in PL XYII., fig. 1, for 
Podostemon Barberi. The transverse section of the group of 
leaves in PI. XVI., fig. 8, includes the section of the pedicel 
of the flower, and an enlargement of this is shown in fig. 9. 
It is nearly circular in section, has a small central vascular 
bundle, a large cortex, and a columnar epidermis, especially 
well marked on the “ upper ” side, so that even in the pedicel 
there is a degree of dorsiventrality. 
As soon as the water-level sinks sufficiently to expose the 
plants, the leaves shrivel and drop away, and the spathes 
open to allow the escape of the flowers. PI. XVI., fig. 10, 
shows a flower fully open. It is without perianth, unless 
the thread-like organs at either side of the common stalk of 
the stamens be regarded as perianth ; it stands on a short 
stout pedicel, nearly erect. On the lower side, Lö., the 
convex side of the shoot, is the andrœceum, consisting of 
two stamens on short partial filaments united upon a longer 
