198 
WILLIS : PODOSTEMACBÆ 
The Asiatic Tristicheœ. — All the Asiatic species are 
referred by Weddell and Hooker to the genus Lawia 
(Terniola), but the morphology of the peculiar South Indian 
species L. ramosissima, Wmg.,is so essentially different from 
that of the Lawias of the L. zeylanica type, that I prefer 
to place it in a separate genus, following Warming ; I do 
not, however, think that it needs a genus to itself as 
suggested by him. It may very well form a sub-section of 
the almost cosmopolitan tropical genus Tristicha, and 
probably represents a more primitive form with relation- 
ships on one side to the other species of Tristicha and on 
another to Lawia. In many ways this plant may be looked 
upon as perhaps the most primitive in organization of all 
the Podostemaceæ, and in habit and mode of life it comes 
more near to the common type of water plants than any of 
the rest of the order. Including this plant in Tristicha of 
course involves a slight revision of the generic characters, 
and it may perhaps be well also to split the genus into two 
sub-genera, Dalzellia and Eutristicha. 
The Asiatic Eupodostemece (in Warming'' s sense). — All the 
other Asiatic species belong to this group. The group itself, 
as indicated above, is a fairly natural one, but its further 
division into genera and species is very difficult, and will 
only be practicable with any degree of accuracy when we 
shall have acquired a much more detailed knowledge of the 
structure and life-history of its members. Warming in 
1890^" divided it according to the fruit into Isolobæ {Bicrœa^ 
Du Pet. Th., Hydrohryum, Endl., Geratolacis^ Wedd., Ango- 
Icea, Wedd.) and Heterolobæ (Mniopsis^ Mart, et Zucc., 
Podostemon^ Michx., Oserya^ Tul. et Wedd., Castelnavia^Tvd. 
et Wedd., SphcerothylaXy Bischoff, to which have since been 
added Leiothylax^ Wmg., Gladopus, Hj.. Moll., Farmeria^ 
Willis, Willisia, Wmg., Griffithella^ Wmg., Polypleurum^ 
Wmg.). Before going on to the rest of the taxonomy, we 
must deal with these genera, and consider their right to 
autonomy. Angolæa is an apparently well-marked African 
* Engler and Prantl, Die Natürlichen Pfianzenfamilien. 
