CXL. ORCHIDACE^. 529 



CansjKctus of tlie Genera. 



I cordate, pefiolate. • . . Hijdrpchcjls. 1 



< short anil verticillate, sessile. Flowers axillary, solitary Udora. 1 



Leaves ( long. Linear, radical. Flowers elevated on Ions scapes VaUisneria. 3 



1. HYDROCHARIS. 



Gr. vSwp, water, ;i^aip(j, to rejoice ; as water is its own element. 



Flowers J* 9. — Spathe 2-leaved ; calyx S-parted ; corolla of 3 pe- 

 tals ; styles 3, abortive in the cf; sta. 10 — 12, infertile in 9 ; stig. 

 6 — 8, bifid, with several barren filaments and 3 nectariferous glands • 

 caps, inferior, 6-celled, 00-seeded. — Floating aquatics. 

 H. spoNGiOsA. Base. (H. cordifolia. Nutt.) Frogbit. 

 Lis. roundish-cordate ; J^ fis. on long pedimcles, 9 on short ones ; anth. 

 linear; stig. 6 — 7, 2-parted nearly to the base; segvwnts lanceolate-subulate. — % 

 Braddock's bay, L. Ontario, S'artivell. Stems jointed, producing offsets from 

 which new plants arise. Root somewhat fibrous. Leaves petiolate, 5-veined, 

 purplish beneath. J* peduncles about 3' long. Sepals oval, green. 9 pedun- 

 cles 1 — 11' long, thick. Ovary oblong. Seeds hirsute. Petals white. Aug. 



2. UDORA. Nutt. 



Gr. v6o}p, wafer ; from its aquatic habita. 



Flowers c? 9; spathe bifid ; spadix 1 -flowered. 3" Stamens 9, 3 of 

 them interior. 9 Tube of the perianth very long ; abortive filaments 

 3 ; capsule ventricose, 3-seeded. — Creeping. Lvs. verticiilate. 



U. Canadensis. Nutt. (Elodea. Michx. Sepicula verticillata. Muhl.) 

 Dit-ch Moss. — Lvs. verticiilate, in 3s and 4s, lanceolate, oblong or linear, 

 serrulate; tube of the ferianth filiform. — Resembling a coarse moss, in still 

 waters. Stem filiform, diffusely dichotomous, very leafy, submersed. Leaves 

 3 — G" by (less than^ 1", thin and diaphanous, sessile, obtuse. Flowers axillary, 

 solitary, minute, ol a dingy white, the slender, hair-like tube 2 — 3' long (4 — 6' 

 according to Nuttall), the lower part (pedicel 1) 2-margined. Stigmas recurved 

 between the segments, crested with glandular hairs. Aug. 



3. VALLISNERIA. 



In honor of Anthony Vallisner, a French botanist. 



Flowers J" 9 ; spathe ovate, 2 — 4-parted. c? Spadix covered with 

 minute flowers; corolla 0. 9 Spathe bifid, 1 -flowered; perianth 

 elongated ; sepals linear ; stigmas 3, ovate, bifid ; capsule 1 -celled, 

 many-seeded. — %■ Submersed. Lvs. all radical. Scape spiral^ very long. 



V. Americana. Michx. Tape Grass. 



Lvs. linear, obtuse, serrulate at the end, tapering at the base, floating ; 

 peduncle of the fertile fiower long, of the sterile short, erect. — A curious plant, in 

 slow moving or stagnant waters, ' U. S. Leaves linear, 1 — 2f long, about J' 

 wide, the edges thinner than the middle. Scapes several, of the sterile plants 

 short, of the fertile plants very tortuous, 2 — 4f long when extended, thread-like, 

 thickened at top, bearing each a single, white flower at or near the surface! 

 Sepals and petals crowning the (1') long, narrow, incurved ovary, which is 

 half concealed in the spathe. July, Aug. 



Order CXL. ORCHIDACE^.— Orchids. 



Herbs perennial, often acaulescent, with fleshy corms, or tuberous, fasciculated roots. 



Lvs. simple, parallel-veined, entire. Fts. in terminal or radical racemes, spikes or panicles, rarely solitary. 



F!s.—VeTy irregular, with an adherent, ringent perianth of 6 parts. 



Cal. — Sepals 3, usually colored, odd one uppermost by the twisting of the ovarj'. 



Cor.— Petals 3, usually colored, odd one lowest by the twisting of the ovary. 



Lip. Uabellum, or lowest petal,) diverse in form, often lobed, frequently spiured at base. 



Sta. 3, united into a central column, the 2 lateral ones generally abortive, and the central one perfect; 



more rarely the central abortive and lateral perfect. 

 Anth. 1, 4 or 8-celled, persistent or deciduous, often operculate. 

 Pol. either powdery, or cohering in wa.xy masses (polUnia), which are either constantly adhering to a 



gland, or becoming loose in their cells. 



