FORM AND FUNCTION 131 



The true parasites are quite devoid of chlorophyl 

 and are entirely dependent on their hosts. Some 

 which grow on roots have, like the common CHRIS- 

 TISONIA of our hills, a short stem and colourless scale- 

 like leaves, or like BALANOPHORA, practically no 

 stem at all, but only a few scales and a mass of 

 flowers forming a large warty lump on the roots of 

 trees. Others like the common CASSYTHA, and CUS- 

 CUTA the Dodder, grow on the branches of soft 

 barked shrubs and herbs, looking like strands of 

 yellow string, but attached to the host by numerous 

 haustoriums, and with no leaves. All these parasites 

 and semi -parasites have perfectly normal flowers 

 however much the rest of the shoot may be reduced. 



6. In all these types, in the stout trunk of a tree 

 with perhaps its buttressed base, or the thin flexible 

 stem of a twiner, in the weak bifarious branches of 

 a creeping herb, the bulb or tuber of a perennial, 

 and the peculiarities of a parasite or an epiphyte, we 

 see examples of the intimate connexion between 

 form and function which we came across in our study 

 of cotyledons. And this is emphasized by the fact 

 that the flowers whose function of reproduction is, of 

 course, the same whatever be a plant's vegetative 

 habit, are not affected by these differences. A tall 

 tree and a creeping herb, a root-parasite and a shrub, 

 an epiphyte and a climber, may have flowers of the 

 same size and form. 



