SCROPHULARINEAE 



f73 



into the base of the flower, and guide the proboscis of a bee probing for nectar. 

 Nectar is scantily secreted by a swelling at the base of the ovary, which is strongly 

 developed at the sides and towards the spur in which it is concealed. 



Only bees are able to open the flowers and regularly effect pollination. The 

 head of such a visitor is introduced into the entrance of the flower (4 mm. wide), and 

 while probing for nectar its extended proboscis touches the somewhat projecting 

 Stigma, after which its upper side (or the front of the head) is first dusted with pollen 

 by the anthers of the longer stamens and then by those of the shorter ones. The 

 second flower visited will therefore be cross-pollinated. Should insect-visits fail 

 automatic self-pollination is brought about by the pollen clinging to the hairy lining 

 of the lower lip. 



Visitors. Knuth observed the following. 



On August 8, 1897 (in fields near Kiel), Apis mellifica Z. '^, flying persistently 

 from flower to flower, and therefore effecting crossing. The proboscis of this bee 

 (about 6 mm. long) corresponds to the depth at which nectar is concealed. On 

 August 12, 1897, 2 humble-bees (Bombus tferrester Z. 5> and B. lapidarius Z. J) 

 were also observed, behaving like the honey-bee. Their proboscides, respectively 

 7-8 mm. and 8-10 mm. in length, can easily secure all the nectar. Large numbers 

 of Thrips were also noticed, but they never effected crossing. 



648. Linaria Toum. 



Flowers personate, usually homogamous, and adapted to the visits of bees 

 or humble-bees. Nectar secreted by the fleshy base of the ovary, and stored in 

 a spur. Two projections on the palate serve as alighting platforms. 



2075. L. vulgaris Mill. (=Antirrhinum Linaria Z.). (Sprengel, 'Entd. Geh.,* 

 pp. 317-20; Herm. Miiller, 'Fertilisation/ pp. 431-2; Delpino, ' Sugli appar. d. 

 fecondaz. nelle piante autocarp.,' p. 32 ; Kirchner, 

 'Flora V. Stuttgart,' p. 581 ; Knuth, ' Bloemenbiol. 

 Bijdragen,' ' Bl. u. Insekt. a. d. nordfr. Ins.,' p. 164, 

 'Weit. Beob. ii. Bl. u. Insekt. a. d. nordfr. Ins.,' 

 p. 238, 'Bliitenbiol. Notizen'; MacLeod, Bot. Jaarb. 

 Dodonaea, Ghent, v, 1893, pp. 343-5, vi, 1894; 

 ' Bl. u. Insekt. a. d. Ins. Norderney.') The flowers 

 of this species are bright-yellow in colour, with an 

 orange-yellow nectar-guide on the lower lip. Nectar 

 is secreted by the base of the ovary, and Hermann 

 MuUer states that 'it glides in a smooth, narrow fig. 288 Linaria vulgaris, mhi 



' (from nature). A flower (natural size) 



groove, bordered by short, stiff hairs, which passes seen from the front after removal of the 

 r .1 i u i iL i lower lip. The two pairs of stamens are 



trom the nectary between the two antenor stamens, seen below the somewhat arched upper 

 and thence to the tip of the spur, which it fills to ''p- ''"' '>>^ ^''^^^ '" *^^ ^p*" between 



-^ ^ ' their anthers. 



a depth of 5 or 6 mm. or even more.' Sprengel, 



on the other hand, says that the nectar 'remains in the opening of the spur till 

 a certain amount accumulates, and then rapidly flows down into it,' so that the 

 tip of the spur remains full of air. Hermann Muller examined several hundred 

 flowers, but only found two that agreed with Sprengel's description, and therefore 



