DEVELOPMENT OF PLANTS 381 



set of hairs wither, giving him entrance to this chamber, where 

 he feeds upon the microspores and becomes covered with them. 

 Finally the upper set of hairs wither and he is free to leave the 

 spathe and repeat his work in another inflorescence. 



133. Liliales, the Lily Order. — The members of this order 

 comprise nearly 5,000 species that are widely distributed and 

 extensively cultivated for their showy flowers. We have now 

 reached a point in the evolution of the flower where it has become 

 perfect and the protective spathe of preceding orders is replaced 

 by a well-developed perianth. The floral axis also becomes short- 

 ened and we pass from the spiral series of flowers with their 

 variable number of organs to the cyclic flowers with a definite 

 number of organs arranged in whorls. In the lily order there 

 are five whorls of organs of three members each, the stamens 

 being arranged in two whorls. Note also that this crowding 

 usually results in the complete coherence of the carpels (Fig. 

 287, C). These plants are largely perennial, with underground 

 stems in the form of bulbs or rhizomes. This feature adapts 

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

 of our cultivated lilies 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 plants with bulbs and rhizomes 

 may complete their annual growth before the grosser vegetation 

 that would crowd them out is fairly started (see page 39). 



(a) 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 of- 

 fensive 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 



