77 



Ijengtii of Ijipe of Arisaema Triphyllum CORM8. 

 By F. L. Pickett. 



Ill the suiiiUH-r of litUS the writer's attention was called to tlie siiiii- 

 larily in tlie nuinher of i^rowtli periods of A. tripliyllnin conns coming from 

 plants that ninst have heeii of widely different ages. Three years' observa- 

 tion of inatnre plants in the field and gai'den as well as a stndy of seed- 

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

 period. 



The nnderground stem or conn of A. trijihylhnn is an irregular, flat- 

 tened, oval body composed of an inner starcli bearing parenchyma mass, 

 traversed liere and there l)y vascular strands, covered with a thin layer of 

 brown, scurfy cork, and surmounted by a conical bud. The lower side is 

 flattened, much wi'inkled and often beais patches of loose, disorganizing 

 cork tissue. The liud at the toj) is rather large — in mature plants measur- 

 ing from s 2."inin. thrdugh flic base — and contains the leaves and flowers 

 for a succeeding year's gro\^'th inclosed completely by closely convolute, 

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

 l»etioles of the aerial leaves, but is left exposed bj' their decay. The roots 

 grow out from the base <»f the bud scales and so are quite near the outside 

 of the petiole bases. 



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

 leaA^es a scar, marked by a depression in which the traces of vascular 

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

 conn just newly formed below the peti«>le bases. This large scar is a 

 readily usable guide in ((lunting the number of annual growth periods in a 

 given conn. The number of growth jieriods may also be determined 

 through the following facts. Vigorous plants 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 api)earance, by 

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

 fact has been observetl. 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 nnm- 

 lier of record scars as at the beginning of the observation period. It has 



