342 MONOCOTYLEDONOUS PLANTS. 



rietal ; stigmas 36. Fruit dry or succulent, indehiscent, 

 1 or many-celled. Seeds without albumen ; embryo undivided, 

 cylindrical ; radicle at the opposite extremity from the hilum. 

 Floating plants. Leaves with parallel nerves, sometimes 

 spiny. 



1. UDORA. Nutt. 



Dioecious. Spathe bifid. Perianth 6-pnrfed ; 3 inner seg- 

 ments petaloid. STERILE FL. Stamens 9, 3 of them inte- 

 rior. FERTILE FL. Tube of the perianth very long. Ste- 

 rile filaments 3. Utriculus about 3-seeded. Seeds cylindric. 



Dioecia. Enneandria. 



V. c&nadcnsis XuU. : leaves verticillate in threes and fours, lanceo- 

 late, oblong or linear, serrulate ; tube of the perianth filiform. Elo- 

 <fca canadinsis MicJi. Serpicula verticiliata Muid. 



HAB. Still waters. Can. to Vir. Aug. U.Sl em submersed, 

 diffusely dichotomous. Flowers axillary, very small, white. 

 The plant without flowers resembles an aquatic moss. 



2. VALLISNERIA. Lmn. 



Dioecious. STERILE FL. Sj)athe ovate, 2 4-parted- 

 Spadix covered with' minute flowers. Perianth 3-pnrted. Sta- 

 mens 2. FERTILE FL. Scape very long and spiral. Spathe 

 bifid, 1-flowered. Perianth elongated, 6-parted ; the alter- 

 nate segments linear. Style none. Stigmas 3, ovate, bifid. 

 Capsule elongated, cylindrical, 3-toothed, 1-celled, many-seed- 

 ed ; the seeds attached to the sides. Dioecia. Diandria. 



V. spiralis var. americana Torr. leaves linear and obtuse, equal from 

 the base, 3-nerved, margin minutely and aculeately serrulate ; sterile 

 peduncles very short ; fertile ones spiral. V. americana Mich. 



HAB. Still water. N. Y. to Flor. W. to 111. Aug. U.Leatcs 

 all radical, 2 3 lines broad and very long. 



ORDER CXVI. ORCHIDE^E. Juss. Lind. 



Perianth with a ringent 6-parted limb ; outer segments 

 usually coloured, of which the odd one is often uppermost by 

 a twisting of the ovary; inner segments more petaloid, the odd 

 one or the lip being frequently lobed and unlike the others, 

 and often spurred at the base. Stamens 3, in a double row, 

 epiginous, united in a central column, the two lateral ones, or 

 the central one abortive ; anther persistent or deciduous, 24 

 or 8-celled ; pollen powdery or cohering in definite or indefi- 



