ORCHIDACE^. 873 VALLISNERIA. 



ORDER CXLI. HYDROCHARlDACEiE. The Fros-bu Trite. 



JFls. — DicBcious or perfect, issuing from a spathe. 



Perianth. — Sepals 3, iierbaceous. Petals 3, colored. 



Sta. — Definite or indefinite, epigynous. 



Ova. — Adiierenl to the perianth, single. Stigmas3 — 6. Ovules indefinite. 



2>. — Dry or succulent, indehiscent, 1 or more-celled. Seeds without alljumen. 



A small order of floating plants. Leaves parallel-veined. Native of Europe, Nonh 

 America and the East Indies. Of no imponant use. 



Genera. 

 Leaves short and verticillatc. Flowers axillar>\ solitary. . . . Vdora. 1 

 Leaves long, linear, radical. Flowers elevated on long scapes. . . . Vatlisneria. 2 



1 . U D O' R A . 

 Flowers dioecious; spathe bitid ; spadix l-flowered. Ster- 

 ile. — Stamens 9, 3 of them interior. Fertile. — Tube of the 

 perianth very long; abortive filaments 3; capsule ventricose, 

 3-seedcd. 



Gr. iidcog, water ; from its aquatic habits. Creeping. Leaves verticillate. 



U. C.ANADE'NSIS. Nutt. Elodea Canadensis. JVfc. Serpicula veniciliata. .n/a/i. 

 Leaves verticillate, in 3s and 4s, lanceolate, oblong or linear, serrulate ; 

 tube of the perianth dWfoTm. Resembling a coarse moss, in still waters. Stem 

 filiform, diffusely diciiotomous, very leafy, submersed. Leaves ^ — ^- inch 

 long, about .V line wide, thin and diaplianous, sessile, obtuse. Flowers 

 axillary, solitary, minute, of a dingy wliite, the slender tube about as long as 

 the leaves. Aug. Ditch .Muss. 



2. VALLISNE'RI A. 

 Flowers dioecious ; spatlie ovate, 2 — 4-parted. Sterile. — 

 Spadi.x covered with minute floweis; corolla 0. Fertile. — 

 Spathe bifid, l-flowcred; perianth elongated ; sepals linear; 

 stigmas 3, ovale, bifid; capsule 1-celled, many-seeded. 



In honor of Anthony Vallisneri, a Frencli botanist. Submersed, perennial. 

 Lv3. all radical. Scape spiral, very long. 



V. America'na. 



Leaves linear, obtuse, serrulate at the end, tapering at the base, floating ; 

 peduncle of the fertile Jlowcr long, of the sterile short, erect. A curious plant 

 m slow moving or stagnant waters. Leaves linear, 1 — 2 feet long, about i 

 inch wide, the edges tiiiiiner than the middle. Scapes several, of the sterile 

 plants short, of the fertile plants very tortuous, 2 — 4 feet long when extended, 

 thread-like, thickened at top, bearing each a single, white floivcr at or near 

 the surface. Sep.ils and petals crowning the (1 inch) long, narrow, incurved 

 ovary which is half concealed in the spathe. Jl. Aug. Tape Gruss. 



ORDER CXLIll. ORCHIDACEiE. The Orchis Tribe. 



P!s. — Very irregular, with an adherent, ringent perianth of G parts. 

 Cat. — Sepals 3, usually colored, odd one. nnnermnstby the twisting of the ovary. 

 Gv. — Pctnls 3, u;ually colored, odd one lowest by the twisting of the ovary. 

 1-ip. — {Lafellum, or lowest petal) diverse in form.ol'ien lobe 1, trequeiitly spurred at base. 

 Sta. — 3, united i ito a central column, the 2 lateral ones srenerally abortive, and the eectral 

 one perfect; more rarely, the cei.tral abortive and lateral perfect. 

 GG 



