78 TETRANDRIA.— MONOGYNIA. 



130. SAGINA. Cal. 4-leaved. Pet. 4. Caps. 4-celled,, 



4-valved, many-seeded. 



131. TILL^EA. Cal. 3— 4-parted. Pet. 3—4, equal. 



Caps. 3 — 4, 2 or many-seeded. Stam. sometimes 

 8, 4 sterile. 



132. POTAMOGETON. Cal. 4-leaved. Cor. 0. Anth. 



sessile, alternating with the divisions of the ca 

 lyx. Nuts 4, 1-seeded, sessile. 



133. RUPPIA. Cal. and cor. 0. Seeds 4, pedicellate, 



TETRANDRIA. 



MONOGYNIA. 

 104. CEPHALANTHUS. Button-bush. Rubiacea>< 



C. occidentalis : leaves opposite or ternate. 



HAB. Swamps. July — Aug. V Shrub 4—5 ft. 

 high ; leav. ovate-oblong ;fl. wh., in glob, heads. 



105. DIPSACUS. Teasel. Dipsacece. 



D. sylvestris: leaves rarely connate; scales of the 

 receptacle straight; involucrum curved upward 



HAB. Old fields. July. $. Stem 3— 4 ft. high, ang. 

 and prickly ;Ji. pale blue, in oval heads. 



106. GALIUM. Bed-straw. Rubiacece. 



* Fruit smooth. 



1. G. verum : leaves about 8 in a whorl, linear. 



grooved, scabrous ; flowers in dense panicles. 

 HAB. Pastures. June — July. If. Stem erect, slen- 

 der ; leav. rejlexed ; ft. yellozv. 



2. G. trifidum : stem procumbent, scabrous downward ; 



leaves linear, obtuse, scabrous on the margin and 

 mid-rib ; those of the stem in fives ; of the branches 

 in fours ; flowers in terminal fascicles ; pedicels 

 short ; corolla mostly 3-cleft. 



HAB. Wet places. June — Aug. If. Stem much 

 branch.; leav. broad-linear ; fl. rch., minute. 



p. latifolium : leaves obovate-cuneate. 



HAB. Wet places. 



3. G. tinctorium : stem diffuse, smoothish ; leaves linear, 



somewhat acute, slightly scabrous ; those of the 

 stem in sixes, of the branches in fours ; peduncle 5 

 elongated, mostly 3-flowered. 



