CXL. ORCHIDACE^E. 529 



Conspectus of the Genera. 



JhhorfScfverticiUate, sessile. Flowers axillary, solitary. '.'.'.'.'. Udara. 

 Leaves ( long, linear, radical. Flowers elevated on Ipng scapes vailisnena. 3 



1. HYDROCHARIS. 



Gr. vSup, water, %atf)a), to rejoice ; as water is its own element 



Flowers cT 9 . Spathe 2-leaved ; calyx 3-parted ; corolla of 3 pe- 

 tals ; styles 3, abortive in the cT; 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. Bosc. (H. cordifolia. Nutt.) Frogbit. 



Lvs. roundish-cordate ; $ fls. on long peduncles, 9 on short ones ; anth. 

 linear ; stig. 6 7, 2-parted nearly to the base ; segments lanceolate-subulate. Tj. 

 Braddock's bay, L. Ontario, SartiveU. Stems jointed, producing onsets from 

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

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

 } es 1 !' long, thick. Ovary oblong. Seeds hirsute. Petals white. Aug. 



2. UDORA. Nutt. 



Gr. vi<t>p, water; from its aquatic habits. 



Flowers cT 9; spathe bifid ; spadix 1 -flowered. <? Stamens 9, 3 of 

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

 3 ; capsule ventricose, 3-seeded. Creeping. Lvs. verticillate. 



U. CANADENSIS. Nutt. (Elodea. Michx. Sepicula verticillata. MM.} 

 Ditch Moss. Las. verticillate, in 3s and 4s, lanceolate, oblong or linear, 

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

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

 3 6-" by (less than) 1", thin and diaphanous, sessile, obtuse. Flowers axillary, 

 solitary, minute, of a dingy white, the slender, hair-like tube 23' long (4 6' 

 according to NuttaU), the lower part (pedicel 7) 2-margined. Stigmas recurved 

 between the segments, crested with glandular hairs. Aug. 



3. VALLISNERIA. 



In honor of Anthony Vallisner, a^French botanist 



Flowers c? 9; spathe ovate, 2 4-parted. cT 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. 



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

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

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

 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 (!') long, narrow, incurved ovary, which is 

 half concealed in the spathe. July, Aug. 



ORDER CXL. ORCHIDACE^E. ORCHIDS. 



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



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



Fls. Very irregular, with an adherent, ringent perianth of 6 parts. 



Cat. Sepals 3, usually colored, odd one uppermost by the twisting of the ovary. 



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



Lip. (labellum, or lowest-petal,) diverse in form, often lobed, frequently spurred 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. 2, 4 or 8-celled, persistent or deciduous, often operculate. 

 Pol. either powdery, or cohering in waxy masses (pollinia), which are either constantly adhering to a 



gland, or besoming loose in their cells. 



