The Morphology of Ruppia Maritima. 67 
opposite sides of the rhachis, the latter being homologous to a 
spadix, but not at all fleshy. The flowers are naked and consist 
of two practically sessile anthers, each with its two large sacs or 
thecae separate and arranged transversely on the rhachis, making 
a diamond-shaped arrangement, in the center of which is a group 
of pistils, always four in number in the specimens I have examined 
(Pl. IX, fig. 49)" After the shedding of the pollen, the pistils if 
fertilized develop a stipe or pedicel of considerable length (PI. IV, 
fig. 13). The peduncle, or floral axis, however, elongates whether 
fertilization is consummated or not. After fertilization the fruit is 
drawn below the surface of the water, the elongated peduncle 
usually coiling up to aid in this process (see p. 85). 
In company with most of the submerged plants, Ruppia is per- 
ennial. The majority of the leaves and stems die at the approach 
of cold weather, leaving the living rootstock buried in the mud. 
Some green leaves, however, remain, connected with the rootstock, 
and lie at the bottom of the ditch or pool, so that it is possible to 
collect all of the vegetative organs all winter. 
One locality, indeed, is worthy of note, where Ruppia maritima 
flourishes all winter. Here, possibly on account of springs, the 
water is tempered somewhat, and I have gathered Ruppia in a 
green, vigorous condition, when the surface of the ditch was covered 
with ice over an inch in thickness. Although there are doubtless 
springs here, the water nevertheless contains a large percentage of 
salt. It is quite possible that there are many other similar locations 
where Ruppia grows all through the winter. 
In no case, however, have I found the bulbous winter buds, 
which: have been noted in the Potamogetons by Irmisch (1858). 
As indicated by Britton and Brown (1896 vol. I, p. 79). considerable 
variation exists in Ruppia maritima. Thus, one form which I have 
noticed especially, is of a more slender habit, with narrower leaves 
and stems than those of the ordinary individual. Its branching is 
ultimately quite irregular, although the system accords with that 
of the normal form. This form grows in quiet pools. 
There is, moreover, still considerable uncertainty as to the number 
of existing species of Ruppia (Ascherson, 1889; Sauvageau, 1891, II, 
p- 209; Roze, 1894, p. 479). The question is such a large one that 
it cannot be discussed here, and would require, besides, a careful 
study of herbarium material from different parts of the world. 
I will only state that as far as I can learn from a study of systematic 
1 But see Roze, 1894, p. 479. 
