453 
NAIADACE.E. (PONDWEED FAMILY.) 
2. ZANNICHEEEIA, Micheli. Horned Pondweed. 
Flowers monoecious, sessile, naked, usually both kinds from the 
same axil: the sterile consisting of a single stamen, with a slender 
lament bearing a 2 -4-celled anther ; the fertile of 2 - 5 (usually 
4) sessile pistils in the same cup-shaped involucre, forming ob¬ 
liquely oblong nutlets in fruit, beaked with a short style which is 
tipped by an obliquely disk-shaped or somewhat 2-lobed stigma. 
Seed orthotropous, suspended, straight. Cotyledon taper, inflex- 
ed-circmate. —- Slender branching herbs, growing entirely under 
water, with very slender stems, opposite or alternate long and 
linear thread-form entire leaves, and sheathing membranous stip¬ 
ules. (Named in honor of Zannickelli , a Venetian botanist.) 
1. Z. palustris, L. Style at least half as long as the fruit, 
which is flattish, somewhat incurved, even, or occasionally more or 
less toothed on the back (not wing-margined in our plant), nearly 
sessile, or, in var. pedunculata, both the cluster and the separate 
fruits evidently peduncled. — Ponds and slow streams. July. 
3. ZOSTERA, L. Grass-wrack. Eel-grass. 
Flowers moncecious; the two kinds naked and sessile and alter¬ 
nately arranged in two rows on the midrib of one side of a linear 
leaf-like spadix, which is hidden in a long and sheath-like base of 
a leaf (spathe) ; the sterile flowers consisting of single ovate or 
oval 1-celled sessile anthers, as large as the ovaries, and contain¬ 
ing a tuft of threads in place of ordinary pollen: the fertile of single 
ovate-oblong ovaries attached near their apex, tapering upward 
into an awl-shaped style, and containing a pendulous orthotropous 
ovule : stigmas 2, long and bristle-form, deciduous. Utricle 
bursting irregularly, inclosing an oblong longitudinally ribbed 
seed (or nutlet). Embryo short and thick (proper cotyledon al¬ 
most obsolete), with an open chink or cleft its whole length, from 
which protrudes a doubly curved slender plumule. — Grass-like 
marine herbs, growing wholly under water, with a jointed creep¬ 
ing stem or rootstock, sheathed by the bases of the very long and 
linear obtuse, entire, grass-like, ribbon-shaped leaves (whence the 
name, from £&)crn 7 p, a band), 
1- Z. marina, L. Leaves obscurely 3 - 5-nerved. — Com¬ 
mon in bays along the whole coast; in water of 5°-15°deep; thrown 
upon the shore in great abundance during storms. Aug. 
