DEVELOPMENT OF PLANTS 415 



many of them to dry and steppe regions, from which source many 

 of our cultivated liHes have been obtained. It will be seen that 

 this habit of storing food in underground stems enables these 

 plants to develop their leaves, flowers and fruit during the short 

 rainy season, after which the entire aerial portion withers away 

 and their life lies dormant in the buried stems. This habit is 

 equally serviceable if these plants come into competition with 

 larger forms, as in forests where phmts with bulbs and rhizomes 

 may complete their annual growth before the grosser vegetation 

 that would crowd them out is fairly started (see page 44) . 



(o) The Fawn Lily, Erythronium americanum. — This species 

 may be examined as typical of the order (Fig. 287). This plant 

 has received the atrocious name of adder's tongue, which is 

 offensive and far-fetched, and also of dog-tooth violet, although 

 it is not a violet at all. Burroughs has suggested the very appro- 

 priate name of trout lily, since the mottled leaves often form 

 conspicuous beds on shady banks of streams; but to those who 

 have experienced the spring time in the north country, the term 

 fawn lily seems singularly appropriate. The leaves of the fawn 

 lily spring from deep-seated bulbs that are formed in a peculiar 

 way. The seed germinates on the surface of the soil and forms 

 a very small bulb and a single grass-like leaf. During each suc- 

 ceeding season a larger leaf and bulb are fornied, and when of 

 sufficient size, the bulb sends out one or more runners that pene- 

 trate the soil and develop new bulbs at their tips (Fig. 287, B). 

 In this way the bulbs become deep-seated and rapidly increase 

 in numbers, and after several years they attain sufficient size to 

 develop two leaves and a flower. The mottled leaves have the 

 same habit of rolling up in emerging from the ground, as noted 

 in the skunk cabbage. It is to be observed that the position 

 assumed by the mature leaf of many plants is often strikingly 

 correlated with the extent of the root system. In the Liliales 

 generally, which do not have extensive lateral roots, the hang of 

 the leaves is such as to direct the water that falls upon them 

 towards the center of the plant, a feature doubtless of consider- 

 able advantage to plants living in semi-arid regions. The flower 

 is of a decidedly higher type than any previously studied and it 



