332 A TEXT-BOOK OF BOTANY 
196. Swamp thickets.—A growth of shrubs or low 
trees may invade the sedgy swamp, giving rise to a thicket. 
Tic. 304.—A reed swamp.—After Kerner. 
These shrubs and trees are of very uniform type, being 
mainly willows, alders, birches, etc. 
This series of associations, from pondweed associations 
