548 order cxxxvn. — alismace^e. 



nal clusters, sessile, pubescent ; involucre 2-leaved. Petals ovate, ex- 

 panding in the morning, withering before noon. Filaments covered 

 with a plumose down. — Purple. If. May — June. Upper country. 



Spider-wort. 



2. T. ro'sea, (Vent.) Stem erect, simple, succulent. Leaves long, 

 linear, glabrous, channeled. Flowers hi terminal clusters, on elongated 

 peduncles. Sepals spotted, small, glabrous. — Rose-color. If. Com- 

 mon. May — Aug. 8 — 12 inches. 



Order CXXXVIL— ALISMA'CE^E. ( Water-plantain 

 Family.) 



perianth 6-parted, in two rows. Sepals 3, herbaceous. 

 Petals 3. Stamens usually indefinite. Ovaries superior, sev- 

 eral, 1-celled. Ovules solitary, or in pairs, erect or ascending. 

 Styles several. Fruit dry, indehiscent, 1 — 2-seeded. Albumen 

 none. Embryo curved. Aquatic plants, with parallel- veined 

 leaves. 



Genus I.— SAGITTA'RIA. L. 19—12. 

 (From sagitta, an arrow, from the shape of the leaves.) 



Flowers monoecious. Sepals 3, herbaceous. Petals 3, col- 

 ored. Sterile florets with stamens numerous. Fertile florets 

 with capsules numerous, compressed, each 1-seeded. 



1. S. sagittifo'lia, (Mich.) Stem none. Leaves ovate, sagittate, acute. 

 Lobes long, acute, acuminate, lanceolate, on long petioles, 1 — 2 ft. Flow- 

 ers whorl ed by threes ; the upper ones sterile, the lower fertile. Petals 

 larger than the calyx, round. Stamens numerous. Capsules collected 

 into a globose head. — White. 2{. Aug. — Oct. In wet places. Com- 

 mon. 1 — 2 feet. Arrow-head. 



[The above species is very variable in the form of its leaves, and its 

 flowers are sometimes dioecious.] 



2. S. na'tans, (Mich.) Stem none. Leaves floating, elliptic, lanceo- 

 late, obtuse, entire, 3-nerved, alternate at the base ; the lower ones 

 somewhat cordate, 1-nerved. Scape simple, few-flowered, 3 — 6 inches 

 long. Flowers small ; the upper ones sterile, the lower ones fertile, 

 with the peduncles elongated. Sepals lanceolate. Petals round. Sta- 

 mens 8. Capsules numerous. — White. 2£. May — Aug. In shallow 

 ponds. 6 — 8 inches. 



3. S. lancifo'lia, (L.) Stem none. Leaves oval-lanceolate, very long, 

 entire, somewhat coriaceous, glabrous, on long petioles, 1 — 2 feet. Scape 

 2 — 3 feet long, simple. Flowers verticillate by threes, the upper ones 

 sterile, the lower fertile. Sepals tinged with purple, nearly round. 

 Petals larger than the calyx. Stamens numerous. Capsules numer- 

 ous, collected into a globose head. — White. If. April — June. In 

 marshes. 2 — 3 feet. S.falcata. 



4. S. gramin'ea, (Mich.) Stem none. Leaves linear-lanceolate, entire, 

 3-nerved, 4 — 5 inches long, about half an inch wide, on long petioles. 

 Scape simple. Flowers verticillate; the upper sterile, the lower fertile. 

 Sepals lanceolate, small. Petals larger than the calyx. Stamens about 



