77 



Ijength of IjIfe of Arisaema Trii'Hyllum Corms. 

 By F. L. Pickett. 



In the sniiiiiu-i- of T.KI.s tlie writer's attention was called to the simi- 

 larity in the nunibei' t'Y i,'i'(iwth periods of A. triph.vHnni conns coming from 

 plants that nuist have been of widely different ages. Three years' observa- 

 tion of matnre plants in the Held and garden as well as a stndy of seed- 

 lings has led to the conclnsion that the conn has a fairly well fixed life 

 period. 



The nndergroniui stem or corm of A. triphyllnm is an irregular, flat- 

 tened, o\'al body composed of an inner starch bearing parenchyma mass, 

 tiaversed here and there by vascnlar strands, covered with a thin layer of 

 Itrown, scurfy cork, and surmounted by a conical Imd. The lower side is 

 flattened, nnich wi'inkled and often bears iiatches of loose, disorganizing 

 cork tissue. The bud at the top is rather large — in mature plants measur- 

 ing from S i.jmm. tlii-ough the base^ — and contains the leaves and flowers 

 for a succeeding year's giowtli inclosed completely by closely convolute, 

 thick, fleshy scales. This bud is formed in lat^^ spring, within the petiole or 

 petioles of the aerial leaves, but is left exjiosed by their decay. The roots 

 grow out from the base of the bud scales and so are quite near the outside 

 of the i>etiole bases. 



The falling away of leaves and roots at the end of the growing season 

 leaves a scar, marked by a depression ni which the traces of vascular 

 bundles are clearly visible, and extending entirely around that part of the 

 corm just newly formed below the jietiolc bases. This large scar is a 

 readily usable guide in cdunting the number ol annual growth periods in a 

 given corm. The number of growth periods may also be determined 

 through the following facts. Vigorous jilants usually form one or more 

 lateral buds of varying size at the base of the petioles each year. These 

 buds are carried down, with very little change in size or a]>pearance, by 

 the growth of each succeeding year, ;uid so form a record. The interesting 

 fact has been observed, that after a corm has reached four growth periods, 

 its size seems to have nothing to do with the number of such periods, and 

 that mature plants under observation for three years show the same num- 

 ber of I'ecord scars as at the beginning of the observation period. It has 



