) 
Studies in tlie Morphology and Ecology 
of the Podostemaceæ of Ceylon and India. 
TT is a matter of common knowledge with regard to 
-L families that consist entirely of water plants, that the 
morphology of the vegetative organs is usually complex, 
that the flowers are of simple structure (whether this be 
primitive or due to reduction), and that it is very difflcult 
to determine the systematic position of the order. Well- 
known instances are the families Potamogetonaceæ, Nym- 
phæaceæ, Ceratophyllaceæ. To none do these remarks 
apply with greater truth than to the Podostemaceæ, and 
perhaps no family is as yet so imperfectly known. In 
saying this I by no means forget or undervalue the splendid 
work of Tulasne and Warming, but there is yet room for a 
vast amount of research before our knowledge of this order 
can be regarded as anything like complete or accurate. We 
have, thanks to Tulasne, a good knowledge of the general 
morphology of the flower and fruit, and thanks to Warming 
of the morphology of the secondary shoots and thallus of 
many genera, chiefly South American, but this is practically 
all. The germination, the morphology of the primary axis, 
the development of the mature plant from the seedling, and 
[Annals of the Royal Botanic Gardens, Peradeniya, Vol. I., Pt. IV., September, 1902.] 
BY 
J. C. WILLIS. 
( With Plates IV.-XXXVIIT.) 
INTRODUCTORY, 
( 37 ) 
Ik. 1 
