THE president's ADDRESS. 25 



structure. These are sometimes short-lived, as in D. indica, a 

 native of the tropical monsoon region which grows in a satur- 

 ated soil and runs through its life-cycle from germination to 

 seeding in one season. More often they are perennial, as in 

 D. rotundifolia, and adapted to climates which show a marked 

 periodicity. In this species the leaves of the rosette wither at 

 the approach of winter, leaving a large central resting-bud on 

 the surface of the bog-moss. During the winter this is buried 

 by the growth of the surrounding moss ; with the warmth of 

 spring the bud starts growth again, the internodes develop and a 

 vertical stem is formed which produces only a small leaf at each 

 node until the surface of the moss is again reached, when it 

 forms the familiar spreading leaf-rosette and develops an in- 

 florescence from the axil of one of the leaves. By piling the 

 moss round the plant during development of the rosette the 

 action may be interrupted and the successive internodes will 

 again lengthen until the surface of the moss is once more reached. 

 About one-third of the species belong to a subgenus which is 

 practically limited to Australasia, and are adapted mainly to 

 life under conditions where a damp winter alternates with a 

 dry season. At the approach of the dry season the plant dies 

 down, and persists during the drought as a bulb which is buried 

 deeply in the soil ; the plant is what is termed geophilous. The 

 portion of the stem below ground bears leaf- structures with a 

 much-reduced blade which function as rhizoids. When the 

 surface of the soil is reached a leaf-rosette may be formed, or 

 the stem may continue to elongate, in which case the lower leaves 

 are reduced to small scales with no blade. In the axil of the 

 upper scale-leaves is formed a pair of functional leaves, while 

 higher on the stem the subtending leaf itself develops a blade. 

 The stem may be comparatively short and end in an inflorescence, 

 or be more or less elongated and show in very varying degrees 

 the climbing habit. The climbing organ is the leaf of the first 

 order, which has a much elongated stalk. After the terminal 

 gland of a tentacle has become attached to the supporting 

 object its stalk becomes bent to make a spring-like attach- 

 ment. The bulb consists of very closely united leaves the tips of 

 which only are free : it is renewed each year by a lateral bud 

 developed at the base of the stem which grows down into the 

 older bulb and finally replaces it, except for the outermost 



