96 ANGIOSPERMAE—DICOTYLEDONES 



Darwin mentions cleistogamous flowers devoid of pollen one of which produced 

 a capsule in which seeds were (? parthenogenetically) developed. These appeared 

 normal, but were incapable of germination. 



Visitors. — Vide supra. 



1885. H. globulosa Hook. f. (VV. G. Smith, Card. Chron., London, New Ser., 

 xvii, 1882, p. 570.) — W. G. Smith observed flowers of this species in which flies had 

 been caught by the legs. 



575. Stephanotis Thou. 



The corolla-tube is long, so that only nocturnal Lepidoptera can effect pollination. 

 The clips attach themselves to the proboscis (Delpino, op. cit.). 



576. Ceropegia L. 



1886. C. elegans Wall. (Delpino, ' Ult.oss.,' pp. 224-8 ; Hildebrand, Bot. Ztg., 

 xxviii, 1870, pp. 604-5.) — In this species the visitors are small flies (e.g. Gymnopa 

 opaca Rond.), which when they settle on the flower are held fast for a day by means 

 of stiff hairs. These then become limp and allow the flies to escape with clips 

 holding on to their proboscis. Pollination is now effected of fresh flowers which 

 may be visited. 



Visitors. — Vide supra. 



577. Periploca Toum. 



1887. P. graeca L. (Delpino, ' Sugli appar. d. fecondaz. nelle piante autocarp.,' 

 pp. 14-15; Hildebrand, Bot. Ztg., Leipzig, XXV, 1867, p. 273.) — The flower mechanism 

 of this species deviates from that of other Asclepiads. The five spoon-shaped bands 

 (retinacula) are sunk in the five angles of the stigmatic disk in the direction of the 

 long axis of the flower. The broadened part of each band lies under two loculi 

 belonging to adjacent anthers, and becomes covered with a sticky mass shortly 

 before the flower opens, taking up pollen when dehiscence takes place. When a fly 

 visits a flower its proboscis sticks to the adhesive matter present on the stalk of the 

 spoon, and this is carried off' with the pollen to be transferred to the stigma of another 

 flower. 



LXVm. ORDER GENTIANEAE JUSS. 



Flowers homogamous, protandrous, or protogynous ; usually possessing a large, 

 brightly coloured corolla. Some species are generally dimorphous (Menyanthes 

 trifoliata Z., Limnanthemum nymphoides Hoff?n. el Link, Erythraea Centaurium Pers.). 

 The species of the genera Erythraea and Chlora appear to secrete no nectar ; in 

 other cases there is nectar, which is either accessible to all (Gentiana lutea Z.), or 

 else concealed, in many cases so deeply that only humble-bees or Lepidoptera can 

 reach it. The genera and species which have been investigated belong to the 

 following flower classes. — 



Po (?) : Erythraea, Chlora ; 



E : Gentiana lutea Z. ; 



C : Menyanthes, Limnanthemum, Swertia ; 



