102 TRIGLOCHINEAE 
3. ZOSTERA, L. 
Submersed water plant in salt water. Stems creeping; leaves narrow 
linear, often 2 to 3 ft. long. The flowers are naked, arranged in 2 rows 
of about 10 to 20 in each row, on a long receptacle, which arises at the 
axil of the sheathing leaf, and which is nearly enclosed by it. Each 
flower consists of an anther or of a pistil. These alternate in the 2 
rows, each being sessile. 
Z. marina, L. (Fig. 9, pl. 6.) Een Grass. Leaves 1 to 6 ft. long, 
less than + in. wide, 3 to 7 nerved. Flower mass 1 to 23 in. long. Along 
the Atlantic coast. 
4. RUPPEA, i 
Submersed plants in salt water with creeping roots and thread-like, 
much branching. stems. Leaves alternate, thread-like, their bases ex- 
panding to a membraneous sheath. From the axil of this sheath arises 
the flower stalk which, at first, is partly enclosed by the membraneous - 
sheath, but as the fruit matures the flower stalk becomes a long thread- 
like spirally-wound peduncle bearing an umbel-like cluster of hard seeds. 
The flower consists of 2 anthers attached directly to the receptacle, each 
so nearly divided in halves that they appear like 4 anthers. These en- 
close several (generally 4) pistils, which are also sessile. 
R. maritima, L. (Fig. 6, pl. 5.) Dircn Grass. MaAriTIME Ruppia. 
Stem 2 to 3 ft. long; leaves 1 to 3 in. long; the slender spiral fruit stalk 
about 1 ft. long. The only species within our limits. Common along 
the Atlantic coast. 
5. NAIAS, L. 
Slender branching submersed plants with leaves generally in whorls 
(3 to 5). Margins of the leaves toothed. Pistillate and staminate 
flowers on different receptacles, sometimes on different plants. Stami- 
nate flower with a eylindric calyx, entire or with 4 diverging points. 
The inner perianth is pelucid, adhering to the single stamen. Capsule 
1-seeded. 
1. N. marina, L. (Fig. 10, pl. 5.) Larcr Naras. Stem stout, with 
whorls of about 3 leaves, which are about 1 in. long by 1/12 broad, 
deeply toothed on the margin with spiny teeth. Several such teeth on 
the back of the central nerve. Lakes, marshes and salt springs, western 
N. Y. and westward. 
2. N. flexilis, Willd. (Fig. 6, pl. 6.) StenperR Natas. Leaves in 
pairs, narrower than No. 1, acute at outer extremity somewhat sheath- 
ing at base. Few teeth on margin. Lakes, ponds and streams, all of our 
area. 
3. N. gracillima, Morong. (Fig. 5, pl. 5.) THREAD-LIKE NAIAs. 
Stem thread-like, branching. Leaves thread-like but minutely notched 
on margins, in 2’s or in verticles of 3 to 5. Ponds, pools. Local in Mass., 
N. Y., N. J., and southward. 
Famity IIJ].—TRIGLOCHINEAE. Arrow Grass FAMILY 
Plants growing in marshes. Leaves half cylindric, stem naked, 
with broad membraneous sheath at base, Flowers small, green or 
