4i8 



A NGIOSPERMAEDICOTYLEDONES 



FlG. 136. Ribes nigrum, L. 

 (after Herm. Mailer). Flower 

 seen from the side, a, anther; 

 ov, ovary; />, petal; s, sepal; 

 sf, stigma. 



describes them as homogamous. The tips of the sepals are of a reddish colour, 

 and the small petals are whitish. The latter incline together above, bringing the 

 introrse anthers so close to the stigma that an insect probing for the nectar secreted 

 in the base of the flower must touch one or two of the ripe anthers with one side 

 of its head and the stigma, which projects somewhat beyond the anthers, with the 

 other side. Cross-pollination necessarily follows. There are, however, but very 

 few insect visitors, and it is usual for automatic self-pollination to take place, the 

 pollen falling from the anthers upon the reflexed margin of the stigma. 



Visitors. Herm. Mfiller saw Apis mellifica L. J visiting the campanulate 

 flowers (5 mm. deep). MacLeod made the same observation in Belgium. The 



latter also noticed that the honey-bee extracts nectar not 

 only from open blossoms, but also opens the older buds 

 with its jaws, and during this process dusts the already 

 mature stigma with pollen brought from other flowers. 

 MacLeod further observed ants, which use a lower flower 

 as a ladder in their attempts to reach the nectar, from 

 which the pendulous character of the flowers and the 

 reflexed sepals keep them away. From below they 

 licked the stigmatic secretion, but were unable to 

 penetrate into the base of the flower. Plateau (Belgium) 

 saw Bombus terrester Z. Schenck (Nassau) observed 

 Bombus hypnorum L. 5 and B. pratorum Z. 5. 



986. R. rubram L. (Herm. MtUler, ' Fertilisation,' p. 250.) The flowers of 

 this species belong to class C. They are greenish-yellow in colour, and Hermann 

 Miiller describes them as homogamous. The bells are tolerably flat, and widely 

 open, so that the nectar is easily accessible. As in R. nigrum, insect visitors usually 

 effect crossing. Automatic self-pollination is only possible for flowers that hang 



obliquely, in which case pollen falls from 

 the stamens upon the underlying stigma. 



Visitors. Herm. M Oiler observed 

 the following. 



A. Hymenoptera. (a) Apidae: 

 1. Andrena fulva Schr. 9, freq., skg. anc 

 po-cltg. ; 2. A. parvula K. $>, skg. ; 3. A. 

 smithella K. t>, do. ; 4. Apis mellifica Z. , 

 freq., skg. and po-cltg. (b) Tenthredinidat : 

 5. Pteronus hortensis Htg., skg. 



Alfken saw 2 bees at Bremen, both 



skg. 1. Apis mellifica L. g; 2. Nomada borealis Zett. J. 



The following were observed by the authorities, and at the places stated. 

 Loew (Brandenburg) the hover-fly Syrphus lunulatus Mg. ('Beitrage,' p. 37). 



F. F. Kohl (Tyrol) the ruby-wasps Chrysis austriaca F. and C. fulgida Z., and the 



true wasp Odynerus trifasciatus F. Plateau (Belgium) Apis. 



Fig. 137. Ribes rubrum. L. O'rom nature). 

 A. Flower in section. B. Flower seen from above. 

 a, anthers ; ca, calyx ; co, corolla ; s, stigma. 



I. 



987. R. aureiim Pursh. (Herm. Mttller, 'Fertilisation,' p. 251, ' Weit. Beob.,' 

 p. 301; Knuth, ' Bloemenbiol. Bijdragen'; Warnstorf, Verh. bot. Ver., Berlin, 



