172 ANGIOSPERMAE-DICOTYLEDONES 



2073. A. sempervirens Lapeyr. (MacLeod, ' Pyreneenbl.,' p. 41.) The 

 flowers of this species are white in colour, and the swellings on the lower lip 

 pale yellow. Only humble-bees are strong enough to force them open. A pale- 

 violet patch on the upper lip serves as a nectar-guide. The spur is divided by 

 a partition into lower and upper parts, the latter only containing the nectar secreted 

 by the ovary. 



Visitors. MacLeod observed the humble-bee Bombus hortorum L. in the 

 Pyrenees. 



2074. A. Orontium L. (Knuth, Bot. Centralbl., Cassel, Ixxi, 1897.) This 

 species bears homogamous bee flowers. They are of medium size, red, rarely 

 white in colour, arranged in scanty racemes, and therefore not very conspicuous. 

 The rose-coloured (rarely whitish) upper lip is 8-10 mm. broad, and marked 

 with dark-red streaks that converge to the opening of the flower closed by the 

 palate. The lower lip is similarly coloured, but the streaks upon it are feebler, 

 and its summit is marked with a pale-yellow nectar-guide, from either side of 



Fig. 287. Antirrhinum Orontium, L.{iTom m.t\xii. ( i) Flower, seen from the front. (3) Corolla, 

 seen from the side. (Natural size.) (3) Flower with the lower lip pressed down, seen from the front ( x 2). 

 o, 6, anthers of the longer and shorter stamens ; c, stigma ; d, the two rows of bristles which guide the ' 

 proboscis of a bee into the base of the flower ; e, hairs lining the lower lip which receive pollen. (4) Pistil 

 seen from the side ( X 2) ; , nectary. 



which (in rose-coloured flowers) a white zone runs along the lower edge of the 

 closed entrance. If the flower is opened by pulling down the lower lip it will 

 be seen that the red streaks of both lips are continued into the corolla-tube, which 

 is only 6-7 mm. long, and produced below into a sort of spur. The upper lip 

 interlocks by means of a keel-like projection with a corresponding depression of 

 the lower lip, thus closing the flower more firmly. The sides of the lower lip are 

 almost vertical, so that rain-drops falling upon the flower are not able to injure it. 



The four anthers are situated inside the upper lip, immediately below the keel- 

 like projection. Those of the two longer stamens project beyond the stigma, while 

 those of the two shorter ones are at a lower level. The stigma, borne upon a style 

 bent at the end somewhat like a hook, therefore occupies the space between the 

 two pairs of anthers. 



That part of the inner surface of the lower lip which touches the anthers in 

 the closed flower is densely clothed with numerous small yellow hairs. These are 

 to some extent felted together, and the pollen is shed upon them. They are 

 continued into two rows of stiff", yellow, erect, capitate bristles, which run dowr 



II 



