ORDER CXXI. HYDROCHARIDACEiE. 521 



larger than the calyx. — Rose-color. If. April — May. Upper Car. 

 and Geo. 10 — 12 inches. 



10. T. xervo'sum, (Ell.) Leaves lanceolate, ovate, acute, membrana- 

 ceous. Peduncle recurved. Petals oblong-lanceolate, larger than the 

 calyx. — Rose-color. 21. April — May. Middle and upper Car. and 

 Geo. 12 iuches. 



11. T. stylo'sum, (Nutt.) Stein erect, smooth. Leaves sub-petiolate, 

 elliptic-lanceolate, acute at both ends. Peduncle recurved. Petals un- 

 dulate, spreading, larger than the calyx, oblong-obtuse. Fruit succu- 

 lent, globose. — Pale rose-color. 2f. Mountains. 8 — 10 inches. 



Genus II.— MEDE'OLA. L. 6—3. 

 (From Medea, the name of a sorceress.) 



Perianth 6-parted, revolute. Stamens 6. Stigmas 3, united 

 at the base. Fruit 3-celled, each cell 3 — 6-seeded. 



1. M. Virgix'ica, (L.) Stem erect, terete, with small sheaths at each 

 joint. Leaves verticillate around the middle of the stem, 6 — 8 in a 

 whorl, a 3-leaved whorl at the summit, lanceolate, 3-nerved, entire, 

 membranaceous. Flowers terminal, on peduncles arising from the upper 

 whorl. — Yellow. If. May — July. In rich, shaded soils. 12 — 18 

 inches. Indian Cucumber. 



II. PETALOFDE^E. 



I. OVARY INFERIOR. 



Stamens and pistils naked, or inclosed in a regularly devel- 

 oped corolla. 



Group I.— TRIPET'ALJE. 



Plants with calyx and corolla distinct, with 3 petals. 



Order CXXI.— HYDROCHARIDA'CELdE. {Frog-bit 

 Family.) 



Flowers monoecious or dioecious. Sepals 3. Petals 3. 

 Stamens epigynous, definite. Ovary solitary, 1 -celled ; ovules 

 numerous. Stigmas 3 — 6. Fruit indehiscent, 1 or many 

 celled. Albumen none. Floating plants, sometimes with 

 spiny leaves. Flowers spathaceous. 



Genus I— HYDRO'CHARIS. L. 20—9. 

 (From 7iudor, water, and charis, grace.) 



Flowers monoecious. Sepals 3, oval, membranaceous. Pet- 

 als 3, narrower than the sepals. Sterile florets usually with 2 

 filaments, united at the base with a 2-leaved spathe. Fertile 



