48 Notes on Marsilea Villosa. 
pubescence of this species, and probably also of M/. vestita, is a char- 
acter which is dependent on environmental factors. 
Marsilea villosa is now very rare in Hawat, and is not repre- 
sented in many herbaria. The habitats for the plant are old taro 
patches, places where Colocasia antiquorum was cultivated. Accord- 
ing to Robinson’ all specimens of it in the Berlin Herbarium are 
sterile, and those collected by Remy have narrower leaflets and a 
more compact rootstalk than those collected by Chamisso. 
A station for this plant was found in Palolo valley, within the 
city limits of Honolulu, in a small, poorly drained area formerly 
taro patches, but now overgrown with several species of grass and 
sedge, among which are a few large Kiawe trees (Prosopis juliflora). 
Among the sedges was an abundance of Elaeocharis palustris (1,) 
R. Brown, which was recorded from Oahu by Kunth, though its 
existence in the Hawaiian group was doubted by Hillebrand.® 
When the station was first visited in March, an area of about 
two acres was flooded with water, on the surface of which were 
floating thousands of Marsilea leaves. The plants gathered at that 
time were all sterile and were glabrous in all parts except the nodes, 
which varied from nearly glabrous to somewhat woolly (Pl. XIII). 
The length of the petioles varied directly with the depth of the 
water in which the plants were growing—long petioles in deep 
water, short petioles in shallow water—and were of unusual length 
on plants growing in water amongst grass. Plants taken from shal- 
low water near the edge of the pond had petioles ranging in length 
from 3.5 to 4.0 centimeters; whereas many growing in water with 
grass had petioles of 23 centimeters in length. In proportion as the 
water dried up with the advance of summer, the plants became 
more and more conspicuously rusty woolly at the nodes, and the 
under side of the leaves became pubescent with whitish hairs. 
Finally when the water had disappeared, during the last week in 
April of the same year, the plants were found to be densely rusty 
woolly at the nodes, with occasionally a few scattered hairs along 
the rhizome. On a dry hummock a single fruiting specimen was 
found. 
* Robinson, W. J., op. cit. 
* Hillebrand, Wm., Flora of the Hawaiian Islands, p. 474, 1888. 
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