OEGANS OF GROWTH. 



19 



Arum and Orchid families. It is generally a simple 

 body, but also often variously lobed, as in some of the 

 Melanth family. The word corm may also be extended 

 to what are called pseudo-hulbs, whic'^ is applied to the 

 bulb-like and cylindrical stems of man) tropical orchids 

 that grow above and under the surface. 



Phyllocorm (leaf- corm). — This term is applicable to 

 the bulb of the onion, lily, crown imperial and allies ; it 

 differs from the preceding in not being solid, but com- 

 posed of the bases of leaves more or less firmly over- 

 lapping each other ;* such being termed coated or 

 tunicated, and therefore not a true stem. In these the 

 leaves are deciduous. But the term also includes a set of 

 plants with parallel veined permanent leaves seated on 

 an erect, short, or very rudimentai'y axis, the bases in 

 some becoming thickened, swollen, and bulb-like ; the 

 stemless American and African aloes, and others of the 

 lily and amaryllis, nearly the whole of the pineapple, 

 anthuriums, and others of the Arum families being ex- 

 amples, also tuft growing (ccesjgitose) grasses, as pampas, 

 tussac, and dogsfoot. 



There are many special cases difficult to classify under 

 any of the above terms, of which the singular plant known 

 as Elephant's-foot, or Tortoise plant, is an example. 

 Some botanists describe it as a rhizome, while its erect 

 growth, and its developing flower, stems, and leaves from 

 its apex only, indicate it to be more properly corm. Its 

 congener black bryony, a native of this country, is an- 

 other example. 



Plants growing in fresh water are termed Aquatics. In 

 general their root stems agree with the above definitions. 



* See Structure of Stems. 



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