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or peduncle. In fruit the stipe and style lengthen, and the ovary 
is prolonged iuto a flattish, falcate nutlet, ribbed or sometimes 
toothed on the back. Seeds corresponding to fruit; the embryo 
bent and coiled at the cotyledonary end. 
Found in all parts of the world. Halfa dozen different species 
have been described by authors, but most of them can be reduced 
to the following species, and probably not more than 2 or 3 species 
exist. 
I. ZANNICHELLIA PALUSTRIS L, Sp. Pl. 969 (1753). 
Flowering and ripening its fruit under water. Stems capillary, 
sparsely branched, from a creeping rhizome and fibrous roots, 1-2 
feet high. Leaves 1-3 inches long, 1% line or less in breadth, 
acute, thin, I-nerved and with a few delicate cross nerves. Spathe 
or stipule separating from the leaves and fruit at maturity, per- 
sistent. Fruit 2-4, sometimes 6, in a cluster, falcate, 1-2 lines 
long, variously disposed, sometimes sessile, sometimes, as in forma 
pedicellata, J. Gay, each on a pedicel, or, as in forma pedunculata 
A. Gray, the whole cluster on a short peduncle. The fruit is gen- 
erally ribbed or winged on both margins, but sometimes without 
an apparent rib and sometimes dorsally knobbed or toothed; style 
persistent, recurved, 14-1 line long. In var. muricata, Morong, 
which occurs in Texas and California, the fruit has distinct teeth 
on the back and is bristly-muricate on the sides. All these forms 
may sometimes be found on a single plant, or, at least, in the same 
cluster, and can hardly be regarded as varieties. 
Fresh and brackish ponds and pools, sometimes in tidewater. 
Common throughout Canada and the United States, as well as in 
all other parts of the world. (Plate LXIV.) 
7 NATAS; L Sp. PI. 1015 (1753). 
Slender, branching plants with fibrous roots, wholly submerged. 
Leaves opposite, alternate or verticillate in 3's or more, sheathing 
at the base, nerveless. Flowers moncecious or dicecious, axillary, 
solitary, sessile or pedicellate. Sterile flower with a double peri- 
anth, the exterior one entire or 4-horned at the apex, the internal 
hyaline, adhering to the anther; stamen sessile or stipitate, 1—4- 
celled, apiculate or 2-lobed at the apex, rupturing irregularly. 
Fertile flower of a single ovary which tapers into a short style 
