LABI AT AE 313 



734. Prostanthera Labill. 

 In species of this genus the connectives possess long appendages ; visitors strike 

 against these and are sprinkled with pollen in doing so. 



735. Ajuga L. 



Generally homogamous, rarely protandrous or protogynous humble-bee flowers 

 with a very short upper lip, the higher ones and the bracts serving as an imperfect 

 protection for the inside of the blossoms. Corolla-tube with a circlet of hairs ; nectar 

 secreted and concealed as usual. Occasional gynomonoecism. 



2376. A. reptans L. (Sprengel, 'Entd. Geh.,' pp. 299-300; Herm. MuUer, 

 'Fertilisation,' pp. 501-2, ' Weit. Beob.,' Ill, pp. 45-6, ' Alpenblumen,' p. 309; 

 Kirchner, ' Neue Beob.,' p. 59; Schulz, ' Beitrage,' I, p. 87, II, pp. 138-9, 222; 

 MacLeod, Bot. Jaarb. Dodonaea, Ghent, iii, 1891, p. 337, v, 1893, pp. 378-9, Bot. 

 Centralbl., Cassel, xxiii, 1885 ; Loew, ' Blutenbiol. Floristik,' p. 391 ; Knuth, 'Bloemen- 

 biol. Bijdragen.')— The lower lip of the blue, rarely pink or white flowers of this 

 species is marked with brighter lines that serve as nectar-guides. They are generally 

 homogamous, but sometimes protandrous or protogynous. The corolla-tube is 

 9 mm. long, the lowest 2^ mm. being ventricose. The nectar, which is secreted by 

 a thick, yellow, fleshy gland situated on the front of the ovary, is stored in the 

 enlargement of the tube. As the upper lip is almost entirely absent, the anthers and 

 stigma are exserted ; they are protected from rain by the bracts of the flowers 

 situated above. 



The stigmatic branches usually diverge as far in flowers just opening as in older 

 ones, the lower branch resting on the anthers (which lie very close together) of the 

 shorter stamens. It is therefore not touched at first by the smaller insect visitors, 

 which do not press the stamens apart very forcibly, though they are nevertheless 

 sprinkled by the pollen-covered surfaces, that are directed downwards and forwards. 

 The stamens separate later on, and the style drops down between them, so that the 

 lower stigmatic branch with its papillose surface is brought into the entrance, and 

 touched by visitors before the anthers. The length of the style varies, however, so 

 that the stigma is not always situated above the anthers, but sometimes behind or in 

 front of them. In some cases, therefore, cross-pollination is effected more easily, in 

 others, self-pollination. 



The course of maturation of the stigma and anthers also varies : sometimes they 

 mature simultaneously, sometimes one before the other : homogamy is, however, 

 much more frequent than protogyny, and this is commoner than protandry. 



Should insect-visits fail, automatic self-pollination often takes place, the papillose 

 tip of the stigma sliding down through the pollen clinging thickly to the lower side of 

 the anthers ; autogamy is, however, less eff'ective than allogamy. Perforation by 

 humble-bees is not infrequent. 



MacLeod observed a second kind of flower at Ghent besides the ordinary ones. 

 This form is large, markedly protandrous, and more brightly coloured. The corolla- 

 tube is 11-12 mm. long, and the lower lip 8-9 mm. broad. In the second (female) 

 stage the stamens lean backwards, while the style bends so far forwards that the 

 stigma occupies the entrance of the flower. 



