31 o ANGIOSPERMAEDICOTYLEDONES 



is folded together in the median plane. This fold, with the projecting tip of the 

 carina, guides the proboscis of bee visitors, which must be 6-7 mm. long to get 

 at the nectar. In this species too the stigma is surrounded by the pollen of its own 

 flower, but probably this does not adhere to it without pressure. 



Loew has studied this species in the Uckermark, and compared it with those 

 described by Hermann Miiller (' Alpenblumen,' pp. 232-6), i.e. O. uralensis DC, 

 O. montana DC, O. lapponica Gaud., and O. campestris DC. He describes it 

 as intermediate between O. uralensis and O. campestris on the one hand, and 

 O. lapponica on the other hand; for a proboscis 10-13 mm - l n g is requisite for 

 securing the nectar of the first two species, while one 4-5 mm. long is necessary 

 in the case of O. lapponica. O. montana requires a proboscis 8-9 mm. in length. 



The very prominent tip of the carina, and the double union between alae and 

 carina are specially characteristic of O. pilosa. The carina, in accordance with the 

 mechanical arrangements of papilionaceous flowers, is exposed to the greatest 

 pressure and pulling-strain during insect-visits. Loew says that those parts of it 

 most liable to these stresses are best provided with epidermal cells of specifically 

 mechanical nature, the walls of these being either wavy or strongly ribbed. 



It must be added that the outer walls of the epidermal cells covering the folds 

 of the double basal union between carina and alae are strongly papillose, while 

 increased firmness is given by cuticular ridges radiating from the tips of the 

 individual cells. 



Visitors. Loew observed long-tongued dasygastrid bees in the Uckermark. 

 Eucera longicornis L. $ and S, and Osmia aurulenta Pz. 5 ; also some Scopulipedes 

 (humble-bees). In Thuringia Herm. Miiller saw the honey-bee, skg., and Pieris 

 rapae Z., do. Schulz noticed flowers perforated by humble-bees. 



220. Astragalus Toum. 



Nectar-yielding bee flowers, mostly yellowish or violet in colour; with simple 

 valvular arrangement. 



728. A. Glycyphyllos L. (Herm. Mailer, 'Weit. Beob.,' II, pp. 252-3; 

 Heinsius, Bot. Jaarb. Dodonaea, Ghent, iv, 1892, pp. 87-91; Schulz, 'Beitrage,' 

 II, p. 209; Knuth, ' Bloemenbiol. Bijdragen.') The flowers of this species are 

 greenish-yellow in colour. Hermann Muller states that the edges of the carina 

 are so close together in the front part containing the anthers, that they scrape off 

 some of the pollen and leave it outside when the depressed carina moves up again. 

 The alae only interlock with the anterior part of the carina; the lower edges of 

 their finger-like processes, which are broad and flat, abut closely on the sexual 

 column. Only the upper half of the flower is ensheathed by the broad base of 

 the vexillum, which passes gradually into its erect portion. Along the middle of this 

 is a deep groove serving as a guide for the proboscis of bees. An open cleft remains 

 between the claws of the carina and alae through which the honey-bee is in the 

 habit of stealing nectar from the side. 



Visitors. Humble-bees and other long-tongued bees suck the nectar legiti- 

 mately and are effective visitors. Schulz also observed flowers perforated by 

 humble-bees. 



