GENERAL CHARACTERS OF PLANTS 3 



Besides these common forms there are roots of a somewhat 

 exceptional character, such as the aerial roots or suckers which grow 

 from the stem of the Ivy and serve to support the plant ; and the 

 roots of the Mistletoe, which, instead of penetrating the soil, force 

 their way into the substance of certain trees, from which they derive 

 the necessary nourishment. 



The student of plant Ufe must always be careful to distinguish 

 between roots and underground stems, for there are many exaraples 

 of creeping and tuberous stems which resemble certain roots in 

 general appearance. A true root bears no buds, and, therefore, is 

 not capable of producing new plants. If a root creeps under the 

 ground, as does the root of the Barley Grass, it merely serves the 

 pm-pose of collecting nourishment from a wider area — a matter of 

 considerable importance when the soil is dry and deficient in suitable 

 mineral food. A creeping stem, on the other hand, developes buds 

 as it proceeds, each bud giving rise to a new plant ; and the creeping 

 itself is the result of the growth of a permanent terminal bud. 



Again, when studying plants for the purpose of identification, 

 it is often important to note whether the root is annual, biennial, or 

 perennial ; that is, whether the root Hves for one season only, lives 

 throughout the winter, and supports the plant for a second season, 

 or retains its life for an indefinite number of years. 



Most of the roots that five over one season are of a fleshy nature, 

 thick and tapering, or tuberous, and contain more or less stored 

 nourishment w^hich assists the new growths that are called forth by 

 the warmth and light of the early spring sun. 



The Stem 



The stems of plants exliibit a much greater variety of structure 

 and habit than do the roots. Then chief functions are to support 

 the leaves and flowers, and to arrange these parts in such a manner 

 that they obtain the maximum of light and air ; also to form a 

 means of communication by which the sap may pass in either 

 direction. Stems also frequently help to protect the plant, either 

 by the development of thorns or prickles, or by producing hairs 

 which prevent snails and slugs from reaching and devouring the 

 leaves and flow^ers. 



The character of the stem is often of some importance in deter- 

 mining the species, so we must now note the principal features that 

 should receive our attention. 



B 2 



