88 



THE PLANT WORLD 



tional activity of the whole plant. Wherever such repairs are made the 

 series of changes in developing parts is approximately the same as that 

 in the development of parts of a seedling of the same species. In the 

 Trilliunis the first leaf after the cotyledon is petioled, so to speak, by its 

 sheathing base. Occasionally its blade diverges somewhat from the erect 

 axis of the plant, and when so divergent becomes green and more leaf- 

 like in texture. It would take but a little more development to produce 

 a perfectly tj^pical blade. Such typical blades are developed at this stage 

 in our Jack-in-the-pulpits. Just such leaves as these were developed on a 

 mature plant of Trilluwi sessile which was described and figured in the 

 Plant World, Vol. 5, p. 92 (May, 1902). Of this plant, Mr. Theodor 

 Holm says : ' ' The little leaves are from ' otherwise ' dormant buds, which 

 in 3'^our specimen have pushed out. Your specimen is injured, since the 

 terminal bud has been re- 

 placed [functionally, the 

 writer would add] by two 

 which have developed into 

 [leaf-] bearing stems. ' ' We 

 may consider all such ab- 

 normal developments as re- 

 parative. 



In contrast to the situa- 

 tion above cited, many 

 plants spring up where the 

 conditions are more or less 

 unsuitable for them. L,ack 

 of moisture at the roots or 

 in the air, too much light 

 or too much shade, crowd- 

 ing by too close neighbors, 

 and a score of other con- 

 ditions affect every species 

 in their normal develop- 

 ment. In Trillhims, per- 

 haps, as well as in any other 

 group, the results of these 

 conditions are recorded in 

 abnormal development, or in atrophy, or in arrest of development pre- 

 viously begun. These results are physiological. 



Abnormal development is shown in the asymmetry of the floral parts 

 in one or more series, irregular and unusual development of pigments, or 

 the unequal growth of leaves otherwise normal. Atrophy, or the arrest 

 of development, may take place in any of these parts. In contrast to 



Trillium, grandiflorum. Physiologically abnormal, with the 

 peduncle 8 inches long, the petioles 8J4 inches long, petals green, 

 with white margins. Drawn by Miss Mausie Cameron after 

 photograph by Mr. J. M. Dickson, Hamilton, Ontario, kindly 

 loaned by Mr. J. M. Macoun of the Canadian Geological Survey. 



