POND-WEED FAMILY 



513 



2. Scheuchzeria. — Leaves linear; flowers bracteate, perfect; 

 perianth of 6 similar, reflexed, green leaves ; stamens 6 ; carpels 3, 

 united below. 



3. Potamogeton. — Flowers in a spike, perfect; perianth of 4 

 leaves ; stamens 4 ; carpels 4, sessile. 



4. Ruppia. — Flowers in a spike, perfect ; perianth absent ; 

 stamens 2 ; carpels 4, at first sessile, afterwards each raised on a 

 long stalk. 



5. Zannichellia. — Flowers 

 axillary, monoecious ; perianth 

 absent ; stamen 1 ; carpels 2 — 6 ; 

 stigmas peltate. 



6. Zosteka. — Flowers monoe- 

 cious, arranged alternately in 2 

 rows on a long leai-like spadix; 

 perianth absent ; stamen 1, 

 sessile, 1 -chambered ; carpel 1, 

 sessile. 



7. NAfAS. — Flowers axillary, 

 dioecious ; perianth absent or 

 4-lobed ; stamen 1 , sessile, 1 — 4- 

 chambered ; carpel 1, sessile; 

 stigmas 2 — 4, awl-shaped. 



1. Triglochin (Arrow-grass). 

 — Roots fibrous ; leaves linear ; 

 flowers in an ebracteate raceme, 

 small, green, inconspicuous, 

 perfect ; perianth of 6 similar, 

 erect leaves ; stamens 6 ; ovary 

 3 — 6-chambered, superior ; stig- 

 mas feathery ; fruit 3 — 6-seeded, 

 separating into dehiscent carpels. 

 (Name from the Greek treis, 

 three, and glochin, a point, from the pointed carpels.) 



1. T. palustre (Marsh Arrow-grass). — A plant with something of 

 the habit of Plantdgo maritima, from which it may easily be 

 distinguished by its fewer flowers and slenderer raceme, as well as 

 by the different structure of the flowers. It has runners ; leaves 

 radical, linear, fleshy, 8 — 10 in. high; flowers in a loose raceme; 

 fruit linear, angular, of 3 combined carpels. — Marshy places ; 

 common. — Fl. June — August. Perennial. 



2. T. maritimum (Sea Arrow-grass). — Like the last, but larger, 

 stouter, and well distinguished by its rounded, ovoid capsule of 6 



L L 



trigl6chin palustre 

 (Marsh Arrow-grass), 



