LEGUMINOSAE 275 



Visitors. — In Dumfriesshire, the honey-bee and a humble-bee have been 

 recorded (Scott-Elliot, ' Flora of Dumfriesshire,' p. 43). 



665. O. Natrix L. (MacLeod, ' Pyreneenbl.' ; Kirchner, 'Beitrage,' p. 40.) — 

 The flowers of this species are yellow, with dark red streaks on the vexillum. 

 Kirchner states that the mechanism agrees with those of the last two species. 



Visitors. — In the Pyrenees, MacLeod observed three Dasygastres (a Megachile 

 and 2 Osmia), and 6 Scopulipedes (an Andrena, 4 Bombus, and an Eucera). 



666. O. rotundifolia L. — According to Briquet ('fitudes de biol. flor. dans 

 les Alpes Occident.'), the rose-red flowers of this species possess a pumping arrange- 

 ment extruding threads of pollen, as in other species of the genus. Insect visitors, 

 mostly bees and Lepidoptera, are very numerous. They usually effect cross- 

 pollination, for the stigma projects beyond the anthers, and does not become 

 sticky until its papillae have rubbed against an insect's body. Automatic self- 

 pollination can take place at the end of anthesis. The uppermost stamen is not 

 fused with the others. Kirchner, however, found it to be united with its neighbours 

 for about 3 mm. at the base, but otherwise free. He also states that the flowers 

 exhale an odour of roses. 



Visitors. — Vide supra. 



202. Medicago L. 



Yellow or bluish nectar-yielding bee flowers, the stamens and pistil of which 

 spring out of the carina. 



667. M. sativa L. (Henslow, J. Linn. Soc, Bot., London, ix, 1867; Hilde- 

 brand, Bot. Ztg., Leipzig, xxiv, 1866, pp. 74-5, and xxv, 1867, p. 283; Delpino, 

 'Sugii appar. d. fecondaz. nelle piante autocarp.,' pp. 26-8, ' Ult. oss.,' pp. 47-8; 

 Herm. Miiller, 'Fertilisation,' pp. 175-8, 'Weit. Beob.,' II, p. 252; MacLeod, Bot. 

 Jaarb. Dodonaea, Ghent, vi, 1894, pp. 336-8; Knuth, ' Bloemenbiol. Bijdragen'; 

 Loew, 'Bliitenbiol. Floristik,' p. 391.) — The bluish or violet blossoms are aggregated 

 into tolerably conspicuous many-flowered racemes. Each individual flower is 7 lo 

 II mm. in length. Nectar is secreted in the usual place, and there is a passage 

 to it on either side of the free stamen, as in similar cases. The pressure exerted 

 by an insect visitor causes stamens and style to spring out of the carina, to which 

 they are unable to return. The elasticity necessary to bring about explosion lies 

 entirely in the upper stamens, and there are two arrangements in the unvisited 

 flower by which this is kept in check. — (i) At the upper basal angle of either carinal 

 petal there is an internal hollow process, forwardly directed, and closely apposed 

 to its fellow, the two together gripping the front part of the sexual column from 

 above. A still more pronounced alar process fits into each of them. (2) From 

 the upper edge of each ala a long fringe-like process runs back, passing upwards 

 and inwards so as to grasp, with its fellow, the upper side of the column at a point 

 about one-third of its length from the base. 



The various processes described forcibly maintain the sexual column in a 

 horizontal position. But should an insect visitor press down the alae and carina, 

 the stamens and pistil spring up out of the carina against the under-side of its 

 body or proboscis. The stigma projects beyond the anthers, and therefore first 



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