PASSIFLOREAE 



453 



the weevils occasionally met with in the flowers as regular agents of pollination, 

 though they might sometimes bring this about. 



1074. T. verbanensis De Not. Cat. Sem. Ort. Bot. Roma (1875). The 

 flowers of this species possess the same mechanism as T. natans. 



XLIII. ORDER LOASEAE JUSS. 



309. Caiophora Presl. 



1075. C. lateritia Benth. (Delpino, ' Altri appar. dicog. recent, oss.') Delpino 

 describes the flowers of this species as markedly protandrous. In the first stage 

 of anthesis the five anthers open in succession, and occupy the middle of the flower ; 

 they afterwards bend back towards the petals. In the second stage the stigma 

 matures, and occupies the position previously taken up by the anthers. 



Visitors. These appear to be bees. 



XLIV. ORDER TURNERACEAE H. B. et K. 



Urban states that about eight-ninths of all the known species of this order are 

 dimorphously heterostylous (Verh. bot. Ver., Berlin, xxiv, 1882). 



XLV. ORDER PASSIFLOREAE JUSS. 

 (including Papayaceae Juss.) 



310. Passiflora L. 



Protandrous, humble-bee (and humming-bird) flowers; with nectar secreted by 

 a fleshy ring in the base of the calyx, and protected by three nectar-covers. 



1076. P. caerulea L. (Sprengel, 'Entd. Geh.,' pp. 160-5; Herm. Muller. 

 'Fertilisation,' pp. 267-8; Warnstorf, Schr. natw. Ver., Wernigerode, xi, 1896, 

 pp. 3-4.) The beautiful flowers of this species are large and very conspicuous. 

 The petals are white, and so is the inner surface of the calyx. There are differently 

 coloured concentric rings which serve as nectar-guides. They consist of a large 

 outer circlet of rays, a small inner one, and the outer nectar-cover. As the nectar 

 reservoir possesses but one ring-like aperture, visitors must go right round the 

 reservoir to get all the nectar. Larger insects only can effect crossing, and it is 

 easy for them to go round owing to the large outer circlet of rays; they move 

 from ray to ray as if on the spokes of a wheel, thrusting their proboscis into the 

 reservoir as they do so. 



In the first stage of anthesis, a large insect (such as a humble-bee) when 

 sucking the nectar, receives pollen on its back from the downwardly dehiscing 

 anthers. In the second stage the styles have curved downwards to such an extent 

 that the now receptive stigmas are lower than the empty anthers. It follows that 

 older flowers are fertilized by pollen from younger ones. 



Warnstorf gives a similar account. Anthesis lasts one day. When the bud 

 opens the five anthers have already dehisced and are directed outwards, in line 

 with the thick stiff filaments. As the flower fully expands, each anther rotates 

 through an angle of 180 in the vertical plane of its filament, so as to bring its 



