92 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



THE PHYSIOLOGY OF PITCHER-PLANTS. 



By Professor Sydney H. Vines, M.A., D.Sc, F.R.S., &c. 

 [Read June 15, 1897.] 



Of all the remarkable and varied modifications of the members 

 of the plant-body, perhaps none are more striking or have excited 

 greater interest than the now familiar "pitchers." They are 

 striking owing to the variety and sometimes beauty of form and 

 colour which they present ; they are interesting on account of 

 the morphological and physiological problems which they suggest. 

 It is impossible for me to discuss their morphology, that 

 is their development and general structure, what parts of 

 the plant enter into their composition, and what resemblances 

 and differences exist between them in this respect : for were I to 

 attempt this, it would prevent me from doing justice to the topic 

 which I have selected as the subject of this lecture, namely, 

 their function and use. I shall, therefore, only incidentally 

 allude to this aspect of the matter. 



The number of genera in which structures, fairly coming 

 under the designation of " pitchers " occur, is considerable ; and 

 are as follows, arranged in their Natural Orders as determined 

 in the " Genera Plantarum " of Bentham and Hooker. Taking 

 first those which are undoubted " pitcher-plants," we have : — 



(1) . Sarraccniacecd ; Sarracenia, Darlingtonia, Heliamphora. 



(2) . Nepcntliacecz ; Nepenthes. 



(8). Asclciriadacece ; Dischidia (in a few species, of which 

 only D. rafflcsiana has been fully investigated). 

 (4 ). SaxifragacecB ; Cephalotus. 



To these may be added the Utriculariea? with their curious 

 " bladders," which, in spite of their divergent form, are essentially 

 u pitchers " : — 



(5). Lcntibulariaccai ; Utricularia (nearly all species), 

 Genlisea, Polypompholyx, Biovularia ; which are all rootless 

 plants : — and to render the account of the physiology of these 

 structures complete, mention must be made of the curious hollow 

 subterranean scale-leaves of Lathrcea Squamaria (Oroban- 

 chaceie) ; as also of some Liverworts {e.g. Frullania). 



Thus,apart from the pitchcred Liverworts, we find that pitchers 



