The Behavior of Swamp Plants
The Course of Study
The definite relations that exist between plants and the conditions which surround them are of constant interest to those persons who see plants as things which are alive and performing work. One set of conditions makes possible a type of plant life which type must be adopted in a general way, at least by all the plants living among these conditions. That this type is adopted in a general way only is clearly shown by the fact that no two plants, even of the nearest kin, are exactly alike, no
... ter how nearly identical the conditions which affect them. Plants which live in water need certain structures which plants living on dry land do not need; and those living on the land of the upward slopes of high mountains, to be successful, must have some structures not found among plants living in the valleys below. As an outcome of these diverse conditions we have certain groups of plants which we recognize as mountain-slope plants; certain groups which are valley plants, and others recognized as water plants. Furthermore, some water plants live entirely beneath the water's surface, while others have their leaves floating or standing above the water. Thus we have a group of submerged water plants and a group of floating ones, each group needing structures peculiar to the demands of the conditions which surround it. These various environ-ments have given rise to "plant societies." By this it is not meant that plants of nearest kin nor of greatest resemblances are associated, but those which have been able to respond to a particular environment by developing the structures needed for successful growth in that environment. Any given plant society usually contains species of plants widely separated in relationship, rather than those of closely related families. A large community in which all the men are blacksmiths would not prosper, since all would demand the same kind of support. Communities of men prosper best when some of the men are blacksmiths, some are merchants, some physicians, and others working in various other lines, thus obtaining their support from the community in a variety of ways. Likewise, if in the plant society all the individuals were alike, or even of the same species, all could not be indefinitely supplied with the necessities of life. But with some kinds of plants needing certain soil and water elements, and other kinds needing other things, the members of the society live together and prosper fairly well, since all do not demand the same thing from the soil or water in which they grow. Notwithstanding this fact of the usual diversity of individuals in a plant society, there are many cases of massing 50I This content downloaded from 191.189.