SOME PLANT MARRIAGES 



425 



plant Ceropegia elegans, though in this case the insects (small flies) are not 

 imprisoned for so long a time, and instead of getting dusted with pollen they 

 leave the flower with the pollinia on their proboscides. In the Dutchman's 

 Pipe (Aristolochia sipho), a native of North America, escape is prevented by 

 the smoothness of the perianth-tube and its curvature at both ends, but 

 when the midges have fulfilled their allotted task, the perianth withers and 

 they are thus enabled to crawl out. Analogous devices are not unknown 

 even among our commoner British plants. The Cuckoo-pint (Arum 

 maculatum) is certainly guilty in this respect. The construction of the 

 flower-cluster s whose 

 prisoner guests are those 

 tiny moth-like flies, the 

 Psychodse has been 

 briefly explained in 

 Chapter X. The flies 

 pass in by the wide en- 

 trance formed by the 

 upper part of the spathe 

 and descend to the lower 

 chamber, which becomes 

 their prison. A number 

 of reflexed hairs (rudi- 

 mentary flowers) encir- 

 cle the spadix in the 

 upper part of the cham- 

 ber, forming a palisade, 

 which, though not pre- 

 venting ingress, cannot 

 be repassed by insects 

 within the chamber, who 

 are bewildered by the 

 sloping rigid bars when 

 they try to fly towards 

 the light. Below the 

 hairs is a closely packed 

 ring of male flowers, and 

 lower still, at the very 

 base of the spadix, a 

 surrounding cluster of 

 female flowers. These 

 mature first, and an- phoio by] 



nounce the fact to the FIG. 528.-NETTLE-LEAVED BELLFLOWER 



-n i i i . . (Campanula, trachelium). 



Psy chodae by emitting a ^ ^ ^ ^^ ^ fof ^ ^ of ^ Nectar provided 



loui ammoniacal odour, the base of the pistn, 



the visits of bees. 

 nd* covered by the expanded bases of the stamens. 



