524 CXXXVII. NAIADACEZ. - PoramoGETon. 
more) ; filament slender, often elongated; anther 4-valved, valves 
spreading. @ Perianth 0; style filiform; stigma 2—3-fid; capsule 
l-seeded—Fls. axillary. 
N. Canapensis. Michx. (Caulinia flexilis. Willd. Fluvialis flexilis. 
Pers.) Water Nymph.—St. filiform, ceespitose, dichotomously branching ; 
lvs. opposite or fasciculate in 3s, 4s or 6s, at the nodes, linear, obscurely denticu- 
late, spreading, 1-veined.—A slender, flexible, rather erect, submersed aquatic 
plant, Can. to N. J. and W. States, consisting of tufts of thread-like, knotted 
stems 6—12’ long. Leaves 4—1’ long, }” wide, sessile and sheathing at base. 
Flowers solitary, sessile, axillary, very small, the fertile ones consisting of an 
oblong ovary tipped with a filiform style, with 2—3 stigmas at summit. _ Aug. 
8. (Caulinia tragilis. Willd.) St. and lvs. rather rigid, the latter mostly 
opposite and recurved. 
3. ZANNICHELLIA. 
In honor of Zannichelli, an eminent botanist of Venice. 
Flowers .—c Stamen 1; filament elongated. 9 Calyx mono- 
phyllous; corolla 0; ovaries 4 or more, each with a single style and 
stigma, and becoming in fruit an oblong, incurved, subsessile achenium. 
Z. PaLusTRIS. Horn Pond-weed. 
St. filiform, floating; dvs. opposite, linear; anth. 4-celled; stig. entire; ach. 
toothed on the back.—In pools and ditches, N. States. Stem round, smooth, 
1—2f long, branching, leafy. Leaves grass-like, 2—3’ long, sessile. Flowers 
issuing from axillary bracts, small, 2 together, a sterile and fertile, the former 
consisting of a single, naked, erect, yellowish-brown stamen, the latter of 4—6 
ovaries which are free from the inflated, one-sided, 2—3-toothed calyx. Jl. Aug. 
S2U PPI 
In honor of Ruppi, a German botanist. 
Flowers %, 2 together on a spadix or spike arising from the sheath- 
ing base of the leaves; perianth 0; stamens 4, sessile; ovaries 4, 
pedicellate, becoming in fruit 4 dry drupes or achenia.— Root U. 
R. MARITIMA. 
A grass-like plant, in salt marshes, Mass. Stems several feet long, fili- 
form, branched, floating. Leaves 1—2f long, linear and setaceous, with inflated 
sheaths at base, all immersed. The common peduncle is contorted and spiral, 
and by winding and unwinding bears the naked, green flowers on the surface 
of the water as it rises or falls. July. 
5. POTAMOGETON. 
Gr. rorapos, ariver, yetrwy, near. 
Flowers %, on a spadix or spike arising from a spathe; calyx 4- 
sepaled; anthers 4, alternate with the sepals; ovaries 4; achenia 
4, sessile, flattened on one or two sides.— Mostly 4, aquatic and sub- 
mersed, only the flowers arising above the surface of the water. Spadix 
(or spike) pedunculate, 3—10-flowered. Lvs. stipulate, parallel-veined, 
lower alternate, the upper (mostly) opposite. Fils. small, greenish. 
§ 1. Leaves of two forms, the upper floating. 
1, P. NaTans? (P. pulcher. Tuckerman.) Broad-leaved Pond-weed. 
Floating; dvs. coriaceous, oblong, or elliptic-ovate, acute or obtuse or cor- 
date at base, on long petioles, submersed ones linear-lanceolate, membrana- 
ceous, elongated, attenuated to petioles at base, lowest reduced to mere petioles, 
all ss: Shomer spikes rather dense, shorter than the peduncles; fr. somewhat 
semi-globose, roughish, more or less carinate at the back.—A very common 
species, in slow waters or ponds, N. Eng.! to Wisc., Lapham! Stem slender, 
