OF INDIA AND CEYLON. 
193 
come a short distance above the thallus, and ultimately 
bears one flower. At the base of the pedicel in these forms, 
and at first covering and protecting it, are several bracts, 
formed from the last vegetative leaves of the axis by the 
enlargement of their sheathing bases and the fall of the 
blades. The examination of herbarium specimens showing 
these bracts in many different stages of this process has led 
to many errors. Thus Podostemon acuminatus, Wedd., 
receives its characterization from having acuminate bracts, 
the specimen examined having been gathered before the tips 
of the leaves had fallen. Dicræa pterophylla, Wedd., is 
characterized from the keel at the back of the bract ; the 
species is identical with D. Wallichii, but the specimens 
examined by Weddell had been taken from younger plants 
in which the keel had been less disintegrated. Trimen, 
in his Ceylon Flora, describes Hydrobryum olivaceum as 
leafless, as in fact it is in herbarium specimens ; in reality 
it is densely leafy, but the leaves fall when exposed. 
The Leaves . — These are usually of the simplest descrip- 
tion. They are very delicate, and in herbarium specimens are 
usually missing, or have lost their tips. The interesting 
change to bracts of some of the vegetative leaves at the end of 
the wet season has already been mentioned. The hairiness of 
the leaves in many species is noteworthy, as it is unusual in 
water plants. The leaves of the Asiatic species are simple, 
but in some cases, where they have been pressed tightly 
together, have been mistaken for compound. 
The Spathe.—Th.Q morphology of this organ is not yet quite 
understood; in all probability it represents two or more united 
leaves. From a taxonomic point of view the chief feature to 
note is the way in which it opens to allow the escape of the 
flower. In Hydrobryum and Farmeria it is usually prostrate 
or nearly so, and opens chiefly on the upper side, while in the 
other genera it is more or less erect, and splits at the apex 
into a number of teeth. These are often so uniform as to 
give the impression of a perianth, but examination of a 
