458 NAIADACEAE. [ Ruppia. 
or closely invested by a hyaline perianth, sessile in the sheathing base _ 
of the leaf, with 2—4 ome stigmas or style-branches and 1 basilar 
anatropous ovule. Fruit sm seed-like nut. Embryo straight. — 
Submerged fresh-water ids with thread-like creeping rhizome. Leaves 
opposite, ternate or alternate, often crowded in clusters, linear, sheathing 
at the base, nerveless, usually serrulate. Flowers solitary or glomerate. 
Ten species, widely dispersed over the temperate and tropical regions. 
1. N, major, All. var. angustifolia, A. Braun, in Seem. Journ. Bot. ELA eS 
Stem almost smooth. Leaves narrow-linear, with 5—10 short patent 
teeth on each margin, the sheath generally toothless. Flowers dioecious, 
solitary. Staminal perianth or spathe bicuspidate. Stigmas 3. Nut 2—3", 
ovoid, erustaceous, F rugose or reticulate. — N. marina, «, L. — N. fluviatilis, 
a th, Enum. Pl. 
Collected by Chamisso on Oahu. The aidcies occurs in lakes and ponds over the 
greater st of the northern hemisphere. 
2. RUPPIA, 1: 
Flowers hermaphrodite, naked, 2—6 sessile on a slender spadix which 
is at first enclosed in the sheathing spathe-like base of a leaf. Anthers 2, 
sessile, each with 2 large and distinct reniform cells dehiscing outwards. 
Carpels 4, small, sessile, free, with a single campylotropous ovule sus- 
pended in each. Stigma waite: waaay Fruit of little ovoid beaked 
drupes, each raised on a slender stalk ich appears after flowering; the 
spadix itself also then raised on an see thread-like peduncle. Embryo 
ovoid, with a short pointed plumule from the upper end, by the side of 
the short ee — Submersed salt-water plants with long and thread- 
like forking stems. Leaves opposite and alternate, slender, almost capillary, 
with as pederen stipuliform base, Flowers rising to the surface at the 
time of expansion. 
One or several species of the temperate and subtropical regions. 
1. R, maritima, L. — Kunth, Enum. Pl. ITI, 123. — Leaves linear-capil- 
lary. Spadix generally 4-flowered, erect or deflexed. Fruiting peduncle ca- 
pillary, 1/2—1‘ long. Nut oblique 
In shallow waters along the coast, found by Chamisso and the Molokat. hes scclih 
*s Expedition, also by the writer on the southern shore of Moloka 
extends over the cgasts of Europe, western Asia and N. Ame rica 
3. POTAMOGETON, L. 
Flowers hermaphrodite, ere bractless. Perianth herbaceous, of 
ed and clawed segments valvate in the bud. Stamens 4, opposite 
the segments, the anthers nearly sessile, 2- called; the ps discreet, 
laterally. Carpels 4 (rarely 1), each with 1 ascending campylo 
tropaus ovule; stigmas sessile, peltate, or introrse on a short style. Nutlets 
