956 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



BULB-EXTENSION IN DECIDUOUS ANDINE AMARYLLIDS. 



By A. Worsley, F.R.H.S. 



Among the following genera and sub-genera indigenous to the Andes, 

 viz. Ismene, Elisena, Chlidanthus, and Habrantlms [and probably also in 

 Placea, Phycella, and Eucrosia], certain characteristic bulb-growth has 

 been noticed by various writers. None of these writers have, as far as I am 

 aware, given any comprehensive explanation of the facts which they had 

 noted. In place of this we find rather disjointed notes scattered over a 

 vast literary field, and in fact many mutually destructive theories have 

 been advanced to explain what some considered abnormalities. 



Other authors — and these are the majority — take the very superficial 

 view that such bulbs are drawn underground by the action of their " con- 

 tractile " roots. Without denying that the roots of these bulbs may 

 exercise a special function of this kind, yet I am convinced that we 

 should not seek here for the sole, or even the main, cause of subsidence. 

 Such bulbs begin to bury themselves before they have any true roots, 

 and continue to do so after, but not solely because, root action has begun. 



The life-history and race-history of these plants show that they sustain 

 a constant struggle to bury themselves in the soil. 



On germination of the seed the original process (the cotyledon of some 

 writers) transposes the embryo from the seed and causes it to undergo the 

 process of weaning often half a foot deep in the ground. (See p. 853, 

 fig. 191.) 



The young bulb, perhaps during its first deciduous period, certainly 

 every year after attaining maturity, loses by decay the whole upper portion 

 of the bulb. Simultaneously a still greater growth and swelling occurs in 

 the lower part of the bulb. 



In the full-size drawing here given the upper half of the bulb is 

 already dead, and the point of issue of the new leaf-growth will be from 

 the constricted middle (or waist) of the bulb upward through a crater- 

 shaped hole in the dead upper part of the bulb (which was filled in the 

 year previous by the bases of the leaves). 



The top of the bulb maintains in the pot its original level, thus showing 

 that, in this case at least, the bulb has not been drawn downwards by 

 " contractile " roots, but the great growth in the lower part of the bulb 

 has in reality formed a new bulb below the original one, and it would 

 appear as though the only part of the plant which persisted from year to 

 year was the root-stock (disc). When leaf-growth recommences and the 

 soil becomes moist the dead upper portion of the bulb will speedily 

 disappear and perish. 



It is very easy to trace this regular process of events in gardens where 

 Ismenes or Elisenas are grown in pots. For to keep them in good health 

 it is almost necessary to repot them all in autumn, at which time every 

 bulb will be found near the bottom of the pot, with the dying old bulb- 

 tunics in various stages of decay above it. 



