LABIATAE 253 



or bee flowers with two stamens, of which the connective is modified into a two-armed 

 lever. The upper anther-lobe, containing pollen, is generally concealed under the 

 upper lip, and thus protected from rain. A humble-bee probing for the nectar 

 secreted at the bottom of the flower by the base of the ovary strikes its head against 

 the generally sterile lower anther-lobe, which is situated in the mouth of the corolla. 

 In this way the fertile upper lobe is brought down on to the back of the insect which 

 is using the lower lip as a platform, and dusts it with pollen. This is transferred to 

 the stigma of a flower in the second stage, when the diverging stigmatic branches, 

 with mature papillae, are situated in the entrance of the flower, and must be touched 

 first by visitors. 



The highest specialization of this lever mechanism is reached in S. glutinosa L. 

 In other species the ' hammer mechanism ' as Kerner, or ' turnpike mechanism ' as 

 Hermann Miiller calls it, is not so perfect, and sometimes the upper lip itself is 

 movable, instead of the connective (S. verticillata Z.), or the style and fertile anther- 

 lobes are not enclosed in the corolla (S. tubiflora Stn.). Those species in which 

 there is a movable joint between filament and connective differ (according to Correns) 

 to this extent, that in one group the lower half of the connective serves not only as 

 a surface to be struck against, but also as a nectar-cover (S. pratensis Z., S. sylvestris 

 Z., S. Horminum Z., S. hispanica Z., S. tilifolia), while in a second group there is 

 a special nectar-cover provided (S. glutinosa Z., &c.). 



Delpino states that in some species there are special adhesive spherules on the 

 anthers (S. verticillata Z., S. ofiicinalis Z., and S. Sclarea Z.), assisting the pollen- 

 grains to cling more closely to visitors. Correns does not confirm this opinion, but 

 says these are ordinary glandular hairs, occurring in other species of Salvia on the 

 most various parts of the flowers, even on those which are never touched by insects. 

 The view expressed by Delpino about the oecological meaning of these structures 

 would therefore appear to be untenable. Brightly coloured bracts serve to increase 

 the conspicuousness of the flowers in many species (S. Horminum Z., S. sylvestris Z., 

 and S. Sclarea Z.). 



2235. S. pratensis L. (Sprengel, loc. cit. ; Axell, ' Om Anord. for Fanerog. 

 Vaxt. Befrukt.,'; Hildebrand, op. cit.; Herm. Miiller, 'Fertilisation,' pp. 477-9, 

 ' Alpenblumen,' pp. 3x5-17, *Weit. Beob.,' Ill, p. 55; Kirchner, 'Flora v. Stuttgart,* 

 p. 616; Schulz, 'Beitrage,' I, p. 78; II, pp. 127-9; Loew, 'Bliitenbiol. Floristik,' 

 pp. 392, 400 ; Correns, op. cit. ; Knuth, ' Bloemenbiol. Bijdragen.') In this species 

 the corolla is usually dark -blue in colour, and directed horizontally. Its tube conceals 

 the nectar secreted by the yellow, fleshy base of the ovary. The lower lip forms 

 a convenient and safe platform for nectar-seeking bees, while the galeate upper lip 

 serves as a protective roof for the fertile anther-lobes. The entrance to the corolla- 

 tube is closed by a plate made up of the two spoon-shaped sterile limbs of the con- 

 nectives, which fuse together in the course of anthesis. The fertile limbs are about 

 three times as long as the sterile ones. As Sprengel observed, there is a movable 

 union between the filament and connective. Correns says that the joint is not 

 a cylindrical one, but a genuine torsion-joint, distinguished by a remarkable 

 elasticity: it can be twisted artificially through 180 while an insect visitor only 

 moves it 35''-6o. 



This joint is kept in place by a shell-shaped broadening of its end ('joint-^ 



