232 THE BIOLOGY OF FLOV/ERING PLANTS 



adventitious roots. The plant may be annual or may take 

 several years to produce its flowering shoot. After flowering 

 it usually dies. 



If we look back over the series we have traced, we see 

 that the partially parasitic Rhinanthus shows little departure 

 from the normal. Tozzia shows reduction of the aerial 

 shoot which is short-lived and has diminished chlorophyll ; 

 there is a well - developed subterranean rhizome. In 

 Lathraea the vegetative part of the plant is entirely subter- 



A^^D. 



Fig. 27. — Cytinus hypocistis, two inflorescences rising from the root 

 of a Cistus shrub. Nat. size. 



ranean though well developed, only the flowering axis comes 

 above the ground, and chlorophyll has completely disap- 

 peared. Finally, in the broom-rapes the vegetative body 

 is reduced to the little tuber and its peculiar roots, v/ith 

 purely absorptive functions. Only the flowering shoot 

 attains any size. 



Balanophora, etc. — The Balanophoraceae are root-para- 

 sites on shrubs and trees. This family is nearly confined 

 to tropical rain-forests, a few species occurring in savannah 

 and bush vegetation, and one, Cynomoriiim coccinemn, the 



