520 



naiadAce^ 



3. Z. pedunculdta, a less common form, has a stamen of inter- 

 mediate length, with a 2-chambered anther, long styles, large 

 stigmas, and stalked carpels. 



4. Z. polycdrpa, a rare form, occurring in the Orkney Islands, 

 has a very short stamen with a 2-chambered anther, 5 — 6 sessile 

 carpels, with very short 5/y/^5 and large stigmas. 



6. ZosTERA (Grass- 



wrack). — Grass-like, sub- 

 merged marine plants 

 with creeping rhizomes ; 

 compressed stems; alter- 

 nate, long, linear, sheath- 

 ing leaves with adherent 

 stipules ; flowers monoe- 

 cious, arranged altern- 

 ately in two rows on a 

 long, linear, membranous 

 spadix, enclosed in a 

 spathe ; perianth absent ; 

 stamen i, sessile, i- 

 cbambered ; carpels each 

 with I style, 2 stigmas, 

 and I ovule. (Name from 

 the Greek zoster, a girdle 

 or riband, from the form 

 of the leaves.) 



I. Z. marina (Common 

 Grass-wrack). — A com- 

 mon plant in the sea, 

 near low-water mark, with 

 long, cord - like stems, 

 bright green grass-like 

 leaves, i — 3 feet long, 

 3 — 7-veined, and long, 

 leafy sheaths or spathes 

 to the bead-like rows of 

 numerous simple flowers. 

 The dried leaves and stems are collected, under the name of 

 Alva, for stuffing mattresses and packing glass. — Fl. July — 

 September. Perennial. 



2. Z. nana (Dwarf Grass-wrack), an uncommon species, differs 

 in having leaves not more than 6 in. long and i — 3-veined, and 

 fewer flowers in a shorter spathe, with 2 — 5 inflexed membranous 

 appendages or clasping bands. — Fl. April — August. Perennial. 



ZOSTERA makIna {ConuHOti Grass-wrack). 



