Class IV. Order I. 49 



An aquatic, remarkable for its very hard, triangular, axillary 

 fruit. The leaves stand alternately on the stem, are narrow, 

 pointed, with very acute serratures. When the plant grow? in 

 the water, its immersed leaves are cut into linear segments. 

 Flowers two or three in the axil of each leaf. Nut bony, three 

 sided, three celled. Found in meadows and ponds. June, July. 



Class IV. TETRANDRIA. Four stamens. 

 Order I. M O JVO G YNM. One style. 



54. CEPHALANTHUS. Proper calyx superior, fun- 

 nel form ; common receptacle globular ; seed one, 

 downy. 



55. PLANTAGO. Calyx four cleft ; corolla four 

 cleft, inferior, with a reflected border ; stamens very 

 long ; capsule two celled, opening transversely. 



56. CENTAURELLA. Calyx four parted ; corolla 

 four parted, somewhat bell shaped ; capsule invested 

 with the permanent corolla and calyx, one celled, two 

 valved. 



57. MITCHELLA. Corolla monopetalous, supe- 

 rior, two on each germ ; stigmas four; berry bind, 

 four seeded. 



58. HOUSTONIA. Corolla monopetalous ; calyx 

 four toothed ; capsule two celled, two valved. 



59. AMMANNIA. Calyx inferior, tubular, eight 

 toothed ; capsule four celled. 



60. GALIUM. Corolla flat, superior ; seeds two. 



61. CORNUS. Calyx four toothed ; corolla four 

 petalled, superior ; drupe with a two celled nut. 



