154 ANGIOSPERMAEDICOTYLEDONES 



Insekt. a. d. nordfr. Ins.,' pp. 109, 164, ' Bloemenbiol. Bijdragen.') The homogamous 

 nectarless flowers of this species are directed vertically or obliquely downwards, and 

 close at night. The corolla is usually of a pure white colour, but in some cases its 

 lobes are tipped with blue, and not infrequently a narrow blue line runs down the 

 middle of each lobe to the throat, which is then commonly of an orange-yellow. 

 Hermann Miiller regards this coloration as perhaps the beginning of adaptation 

 to cross-pollination by means of flies. The tips of the corolla-lobes are reflexed, and 

 the cone of anthers projects in the direction of the floral axis. The stigma protrudes 

 a little beyond this cone, and pollen escapes from the terminal pores of the anthers 

 when the flower is vigorously shaken. Insect visitors climb up from below on the 

 erect somewhat curly hairs covering the short stiff" filaments. 



Visitors. The following were recorded by the observers, and for the localities| 

 stated. 



Sprengel, bees: 'They struck vigorously against the anthers, so that pollen 

 fell out, and little white balls of this were to be seen on their hind-legs.' Knuth, 

 bees (Apis, Anthophora sp., Bombus agrorum F., and B. terrester Z. ^). Herm.j 

 Miiller, 2 po-dvg. hover -flies Melithreptus scriptus Z., and Syritta pipiens Z. 

 Buddeberg, 2 po-dvg. hover-flies Ascia podagrica F., and Syritta pipiensZ. MacLeod 

 (Flanders), the hover-fly Syritta (Bot. Jaarb. Dodonaea, Ghent, vi, 1894, p. 371). 



2027. S. rostratum Dun. (Herm. Miiller, Kosmos, Stuttgart, xii, 1883.) 1 

 In the flowers of this species the style is turned to the right or left. (For a fuller] 

 description cf. Vol. I, p. 107.) 



627. Physalis L. 



Flowers protogynous ; with concealed nectar secreted at the base of the ovaryj 

 and stored at the bottom of the corolla-tube. Described as ' revolver flowers ' b; 

 Kerner. 



2028. P. Alkekengi L. (Sprengel, 'Entd. Geh.,' p. 127; Kirchner, *Floi 

 V. Stuttgart,' p. 569; Kerner, 'Nat. Hist. PI.,' Eng. Ed. i, II, p. 366.) Th( 

 protog)'nous dirty-white flowers of this species are either pendulous or directed 

 obliquely downwards. The lobes of the corolla are spread out flat, and marked 

 with green veins serving as nectar-guides, besides which there is a circle of green 

 spots above the insertions of the stamens. In the bottom of the corolla-tube 

 there is a small quantity of nectar, protected from unbidden guests by hairs 

 which line the tube at the bases of the filaments. Kerner describes five grooves 

 in the corolla, which abut against the woolly filaments in the centre of the flower 

 so that tubular passages are formed. (' Revolver flowers.') The pollen-covered 

 sides of the anthers are so disposed at the opening of the flower that they m 

 be touched by insects probing for nectar. 



Kirchner states that the stigma is mature when the flower opens, at which 

 time it projects about 4 mm. beyond the still undehisced anthers. The stamens 

 are at first curved outwards and their anthers dehisce extrorsely. Later on they 

 approach the stigma, which still projects beyond them, and as this remains receptive 

 automatic self-pollination can now easily take place by fall of pollen. Kerner 

 describes a subsequent growth of the corolla-tube, by which the anthers are brought 

 up to the stigma and autogamy effected. 



1 



I 



