344 ANGIOSPERMAE—DICOTYLEDONES 



einricht. einheimisch. Pfl.,' Stuttgart, 1886, pp. 36-7; Knuth, ' Bloemenbioi. Bij- 

 dragen.') — In this species the cup-shaped receptacle is 8 mm. long ; for a height 

 of 5 mm., according to Herm. Miiller, it is lined with an orange-coloured layer 

 that secretes nectar. The flowers are therefore better adapted for visits from 

 long-tongued insects than the other flowers of this order. Kirchner states that 

 the roots of the filaments are so curved towards the style as to lie closely 

 together, thus blocking the entrance to the receptacle and its contained nectar. 

 The size of the flowers varies greatly in the different varieties. 



Visitors. — In the Kiel Botanic Garden I noticed the honey-bee, skg., and also 

 2 humble-bees. — i. Bombus lapidarius L. 5, skg. ; and 2. B. terrester L. 5, do. 

 Kirchner saw Apis, Bombus sp., and Vanessa urticae L. in Wurtemburg. Herm. 

 Miiller observed, besides Meligethes, several bees. — i. Andrena albicans MiiU. 5 

 and S, po-cltg. and skg.; 2. Bombus terrester L. 5, skg.; 3. Osmia cornula Z/r. 5 

 and S, do. ; 4. O. rufa L. S, do. Schletterer saw 2 bees at Pola. — i. Bombus terrester 

 Z. ; 2. Xylocopa violacea L. Plateau noticed 3 bees in Belgium. — 1. Apis, freq. ; 



2. Bombus lapidarius L. ; 3. Osmia bicornis Z. 



243. Prunus L. 



White, homogamous or protogynous flowers, with half or completely concealed 

 nectar, secreted in the receptacle. 



820. P. Armeniaca L. — The flowers of this species are white, with a reddish 

 tinge ; they exhale an odour of honey, and Kirchner says that they are homogamous 

 (' Neue Beob. u. d. Bestaubungseinricht. einheimisch. Pfl.,' Stuttgart, 1886, p. 37). 

 The red receptacle forms a cup 7-8 mm. deep, and nectar is secreted by the orange- 

 yellow lower part of its wall, so as to be quite concealed. The stamens are either 

 erect or directed somewhat outwards, so that the access to the nectar is not closed. 

 The ovary and lower part of the style are covered with hairs, that serve to protect 

 the nectar. 



Visitors. — Herm. Miiller observed only Hymenoptera (' Weit. Beob.,' II, 

 p. 244).— 



{a) Apidae: i. Andrena fasciata Wesm. 5, po-cltg.; 2. A. parvula K. 9, do. ; 



3. Halictus leucozonius Schr. j, skg. ; 4. H. sexstrigatus Sc/ienck 5, po-cltg. and 

 skg.; 5. Osmia rufa Z. S, freq,, skg. {b) Pleromalidac; 6. Chalcis sp., skg. 



Schletterer saw the carpenter-bee Xylocopa violacea L. at Pola. 



821. P. domestica L. (Kirchner, 'Beitrage,' p. 35; Herm. Miiller, ' Fertili- 

 sation,' p. 222 ; Knuth, ' Bloemenbioi. Bijdragen.') — The flowers of this species are 

 white with a greenish tinge, and Kirchner says that they are protogynous, though 

 Herm. Miiller describes them as homogamous. The first female condition, accord- 

 ing to Kirchner, lasts almost two days, after which the anthers dehisce ; the flowers 

 remain for three days in the hermaphrodite condition, so that the whole period of 

 anthesis is five days. Cross-pollination is therefore only possible in the first stage. 

 Since the stigma projects beyond the inner stamens, while the outer ones are at the 

 same level, insects are likely to bring about cross-pollination, as they suck the nectar 

 secreted by the fleshy lining of the receptacle, for they usually touch the stigma and 

 anthers of the same flower with different sides of their bodies. In flowers that are 



