258 



TAKING UP OF POLLEN BY INSECTS. 



shining horny leaflets; and thirdly, the two poUinia which are attached to the cHp- 

 like body by ligulate strands belong to two adjacent stamens instead of to a single 

 one. A transverse section through the flower of Äsclepias Cornuti (see fig. 269^) 

 shows in the centre a five-sided column; adnate to each of its sides is a tumid 

 bilocular anther with membranous wings running down its lateral margins. The 

 wings are not appressed to the column, but are reflexed, and stand out in pairs, with 

 the free margins of the two wings in each pair converging towards one another. 

 This produces the same efiect as if the anthers coating the central column were slit 

 through longitudinally in front of every corner of the pentagon. Owing to the 

 fact that the swollen part of each anther bears a curious excavated structure, it 

 comes about that the pollen-producing portions of the anthers are nowhere visible 

 externally save the membranous wings or the five apparent slits, as is shown in 



1 



Fig. 269. — Clip-mechanism for fastening the poUinia of Asclepias Cornuti to the feet of insects. 



I Flower of Asclepias Cornuti seen from the side. 2 xhe same magnified and with two staminal appendages and the front 

 wall of an anther cut away, s Transverse section through the same flower. * Corpusculum (the clip) with two poUinia. 

 6 Foot of an insect with pollinia fastened to it hy the clip. 1 nat. size ; the other figures x 2-5. 



figs. 269^ and 269^). The hollow staminal appendages are full of honey, and each 

 is embellished by a central process shaped like a horn. At the back of every one 

 of the five slits is a little clip-like organ from which proceed ligulate strands 

 connecting it with the pollinia in the adjacent loculi of two difierent anthers (loculi 

 have vertical shading in fig. 269^), the pollen-mass in the left loculus of the anther 

 to the right of the slit being thus associated with the pollen-mass in the right 

 loculus of the anther to the left of the slit. The abundant honey in the staminal 

 appendages emits a scent perceptible from afar, and attracts numberless insects to 

 the flowers. The honey, being stored in a very superficial position, is accessible to 

 insects with short probosces, and, therefore, the chief visitors besides hive- and 

 humble-bees are wasps and Fossores, and these bright-coloured glossy insects — 

 especially the splendid Scolias (Scolia hcemorrhoidalis, S. quadripunctata, S. 

 hicincta) — are a beautiful sight as they hover about the blossoms. During the 

 time when the honey is most abundant the flowers are either nodding or pendent, 

 and they ofier no convenient place for the insects to alight upon, or from which 



