82 SOUTH AFRICAN FLOWERING PLANTS. 



support themselves ; consequently, to prevent falling, 

 they put on '' supportive tissues," of which wood-fibres 

 are the most important. But as tlie water helps to 

 support a submerged stem, which is also filled with 

 air, there is no necessity for much, if any, wood. As 

 a result it is not developed. The general effect of a 

 submerged life is a " degeneration " by the arrest of the 

 formation of internal supportive tissues, and in other 

 ways. 



The Water-lily's leaves and flowers arise from a 

 thick, horizontal stem called a Rhizome. If a section 

 of this be made, the " woody bundles " do not form a 

 ring, but are scattered about, like those in a stick of 

 asparagus, or as described in speaking of the stem of 

 Monocotyledons.^ 



General Description of the Water-lily Family. 



HerU — Aquatic, with thick rhizomes. 



Leaves — Mostly floating, with cordate ^ or j^eltale ^ 

 blades. 



Floivers — Petals numerous, passing into stamens ; 

 carpels, numerous, syncarpous, within a fleshy disc. 



' Seep. 71. ^ I.e. heart-shaped. 



" I.e. shield-like, the petiole entering the middle of tlie blade. 



