316 TETRANDltIA MONOGYNIA. 



* 



t t t Apetalous. 



81. ISNARDIA. Calyx campanulate, 4-cleft; cor. 0; caps. 4-celled, 

 quadrangular, surrounded by the base of the calyx. 



B. Flowers inferior. 



32. PLANT AGO. Calyx 4-cleft ; cor. 4-cleft ; limb reflexed ; stamens 

 mostly exserted, very long; caps. 2-celled, opening all round trans- 



versely. 



83. SYMPLOCARPUS. Spath ventricose, ovate, acuminate ; spadix 

 subglobose, covered with perfect flowers; calyx deeply 4-parted, 

 persistent ; segments cucullate, truncate, becoming thick and spongy ; 

 pet. ; style pyramidal, 4 sided ; stigma simple, minute ; seeds soli- 

 tary, immersed in the spongy receptacle. 



DIGYNIA. 



84. HAMAMELIS. Calyx 4-cleft, with 3 bracts (involucrum) at the 

 base ; pet. linear, very long ; nut coriaceous, 2-celled, 2-horned, cleft 

 at the top ; seed 1 in each cell. 



TETRAGYNIA. 



85. ILEX. Calyx minute, 4 5-toothed ; cor. rotate, 4-parted, or 4-pe- 

 taled; style 0; stigmas 4; berry 4-seeded. 



86. SAGINA. Calyx 4-leaved ; pet. 4 ; caps. 4-celled, 4-valved, many- 



seeded. 



87. POTAMOGETON. Calyx 4-leaved; cor. 0; anther sessile, alter- 

 nating with the divisions of the calyx ; nuts 4, 1-seed., sessile. 



TETRANDRIA. 



MONOGYNIA. 

 specie.. 72. CEPHALANTHUS. Button-bush. 



C. occidentalis : leaves opposite or ternate. 



HAB. Swamps. July Aug. F> ; shrub 4 5 feet high ; leaves ovate- 

 oblong ; Jl. white, in glob, heads. 



73. DIPSACUS. Teasel. 



D. sylvestris : leaves rarely connate ; scales of the receptacle straight ; 

 involucrum curved upward. 



HAB. Old fields. July, $ ; stem 34 feet high, ang. and prickly, 

 Jl. pale blue, in oral heads. 



