M PLANT STUDIES 



A. Stems iearitig foliage leaves 



42. General character. — As the purpose of this stem is to 

 display foliage leaves, and as it has been discovered that the 

 essential life-relation of foliage leaves is the light-relation, 

 it follows that a stem of this t3'po must be able to relate its 

 leaves to light. It is, therefore, commonly aerial, and that 

 it may projierly display the leaves it is generally elongated, 

 with its joints (nodes) bearing the leaves well separated (see 

 Figs. 1. 4, 18, 20). 



The foliage-bearing stem is generally the most eonspieu- 

 ons part of the plant and gives stylo to the whole body. 

 One's impression of the forms of most plants is obtained 

 from the foliage-bearing stems. Sm/h stems have gi'eat 

 range in size and length of life, from minute size and very 

 short life to huge trees wdiich may endure for centni'ies. 

 Branching is also quite a feature of foliage-bearing stems ; 

 and when it occurs it is evident that the jxiwer of display- 

 ing foliage is correspondingly increased. Certain pi'onu- 

 nent types of foliage-bearing stems may be considered. 



43. The subterranean type. — It may seem strange to in- 

 clude any subterranean stem with those that bear foliage, 

 as such a stem seems to be away from any light-relation. 

 Ordinarily subterranean stems send foliage-bearing l)ranches 

 above the surface, and such stems are not to be classed as 

 foliage-bearing stems. ISut often the only stem possessed 

 by the plant is subterranean, and no branches are sent to 

 the surface. In such cases only foliage leaves appear above 

 ground, and they come directly from the subterranean stt'in. 

 Tlie ordinary ferns furnish a conspicuous illustration of 

 this habit, all that is seen of them aliove ground beiiii;- the 

 characteristic leaves, the commoidy called " stem " lu'lna; 

 only the petiole of the leaf (see Figs. 4"), 4(;, 144). ^lanv 

 seed plants can also be found which show tlie same haliit, 

 especially those whi<:h flower early iu the spring, 'I'his 

 cannot bo regarded as a very favorable type of stem for 



