CXL. ORCHID ACEaE. 529 



Conspectus of ike Genera. 



( cordate, petiolate. ■ Hydrocharis. l 



\ short and verticillate, sessile. Flowers axillarj', solitary Udora. 1 



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



1. HYDROCHARIS. 



Gr, v6o)p, water, j^atpw, to rejoice ; as water is its own element. 



Flowers c^ 9 . — Spathe 2-leaved ; calyx 3-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. Bosc. (H. cordifolia. Nutt.) Frogbit. 



Lis. roundish-cordate ; J* Jls. on long peduncles, 9 on short ones ; antk. 

 linear ; stig. 6 — 7, 2-parted nearb/ to the base ; segments lanceolate-subulate. — % 

 Braddock's bay, L. Ontario, Sariwell. 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 — 1^' long, thick. Ovary oblong. Seeds hirsute. Petals white. Aug. 



2. UDORA. Nutt. 

 Gr. v6o)p, water; from its aquatic habits. 



Flowers c? 9; spathe bifid ; spadix 1 -flowered, d" 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 . Muhl.) 

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

 serrulate ; t%ibe of the perianth filiform. — ResemlDling a coarse moss, in still 

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

 3 — G" by (less thaif) I", thin and diaphanous, sessile, obtuse. Flowers axillary, 

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

 according to Nuitall), 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 cf 9; spathe ovate, 2 — 4-parted. d 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 fertik 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 — 41 long when extended, thread-like, 

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

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

 half concealed in the spathe. July, Aug. 



Ordkr CXL. OIICIITDACE.^.— Orchids. 



Herbs pcrenniiil, often nraulesrcnt, with flcRhy romis. or liilieroiis, fii.icictilated r<xit.s. 



Lvs. simple, paraikivtiiiffl, entire. FIs. in ternunal or radical racemes, spikes or pimiclcs, rarely solitary. 



Fto.— Ver>' irrepuiar. with an iidhtrcnl, ririifciit i>cruinlh of 6 parts. 



Ca/.— Sepals 3, u.sually culond, oiUi om; uppermoitt i»y the twistinir of the ovary. 



Cor. — Petals 3, u.simily •oldrefj. ixlrl nne lowest by the twistinp of (he ovary. 



Up. UabtUum, or lowest pctjil.) diverse in furni, often lobed, fre<pienlly npurrcd at base. 



Sla. 3, united into a central colii/un. the 'i luienil ones generally abortive, and the cential one perfect , 



more rarely Die ecntrnl aliorlive and lai( ml perl'ect. 

 Anth. "i, 4 or 8 celled, pernistcnt or deciduous, often opcrciilatc. 

 Pol. either powdery, or cohering in waxy ma.i*c(i (poUinia), whirh arc cither conslanllv adhering 'f 



p!and,or hecominj; loose in thrir rrllv 



