TROPOPHYTES 63 



(Figs. 59, 60). The flower is also there, and so far 

 developed that all its different parts may be quite easUy 

 recognized and separated. In this bud-like condition the 

 plant hibernates out of harm's way, protected from wind 

 and weather, l^s soon as the frost is gone, and the first 

 warm days of spring arrive, the little shoots break from 

 their bulbous cradles and grow into the air. In a short 

 space of time — about two months — -the plant has flowered, 

 set its seeds, and died down again to the ground. 



To what conditions of climate is such a life as this 

 adapted ? Clearly to one where the unfavourable season 

 is long and the vegetative season very short. Some of 

 our bulbous plants, both native (snowdrop) and alien 

 (hyacinth), are the first flowers of spring. Plants which 

 depend upon seed for their renewal require a warmer 

 temperature for germination than buds require for growth. 

 They must therefore wait a httle longer, till the spring is 

 more advanced. This delay is immaterial when the 

 vegetative season is long, but when it is short it is im- 

 portant that the plant should start on its career as soon as 

 possible, and, like the snowdrop, take advantage of the 

 first warm days of spring. 



Most of the bulbs and corms which are cultivated come 

 from the dry and sunny parts of the world. The narcissus 

 is a native of the Mediterranean region, lilies come from 

 Asia Miaor, tulips from Siberia, and the gladiolus from 

 South Africa. In these countries the middle of summer, 

 besides being dry, is very hot, and where this is followed 

 by a long, hard winter, as in Siberia, the vegetative season 

 is reduced to the spring. When the drought of summer 

 comes, most of the ground-flora perishes, and among its 

 earliest victims is the bulbous plant. 



Marsh-Plants. — These plants live in a soil which is 

 always saturated with water, but the greater part of their 

 leaves and stems is in the air. Since water is always 

 abundant, they naturally show many of the characters 

 of water-plants {e.g., large internal air-spaces), and most 

 of them may be submerged for a long time without injury. 

 On the other hand, they agree with land-plants in pos- 

 sessing a good vascular and mechanical system, for they 

 draw their water from the ground, and their assimilating 

 organs are exposed to the air. The air over the marsh is 

 sometimes dry, especially when the wind is blowing. 



