466 
Notes . 
The Mangrove-forests of Satsuma, being situated in 3i°2o' N. lat., 
might be considered at least as the northern limit of Rhizophoreae 
in Asia. I may here state in passing, that the specimen of Mangrove 
collected by Doderlein in Kagoshima and determined by Professor 
Engler (Bot. Jahrbiicher, vi, 1885, p. 63) as ‘ Rhizophora mucronaia ’ 
should be Kandelia Rheedii, on the grounds that the former does not 
extend beyond the Luchu proper in the north, and that in the 
Kagoshima Prefecture the only species to be found there is the 
latter species. 
TOKUTARO ITO, Tokyo. 
FLOATING-APPARATUS OF THE LEAVES OF PXSTIA 
STRATIOTES, L. — This curious aquatic Aroid, commonly growing 
in ponds, ditches, and other stagnant waters of tropical and sub- 
tropical countries, has fleshy, cuneate or obovate leaves arranged 
in a rosette. These leaves are provided on the underside with a 
large swollen body, about the size of a pigeon’s egg. In Trapa 
natans , L., the swimming-organ is developed on the long petiole ; 
but in the case of Pisiia Stratiotes , L., the leaves being sessile, the 
part a little above the base becomes swollen into an obovate form, 
and serves as a floating-apparatus. On making a longitudinal section 
of the leaves, this organ is found to be composed of spongy paren- 
chymatous tissue, containing air. The upper and lower surfaces 
of the leaves are densely covered with minute depressed hairs, which 
protect the leaves from being wetted. By these means, the leaves 
of Pistia Stratiotes , L., are enabled to maintain their position above the 
surface of the water, the upper side is kept dry, and thus the trans- 
piration and respiration are constantly carried on. The above 
observations were made on the plant growing luxuriantly in a pond 
in Shui in the Luchu Islands. 
TOKUTARO ITO, Tokyo. 
