RANUNCULACEAE 



37 



far as the anthers, which in this first (female) condition are still unripe. The carpels 

 project 3-4 mm. beyond them. The extension of the stigmatic surfaces is an 

 adaptation to the movement executed by nectar-seeking insects. 



The filaments now elongate — in centripetal order — until the extrorsely dehiscing 

 anthers completely fill the entrance to the flower, which is about 1-5-2 cm. 

 wide. The carpels also increase in length by a few millimetres. At the beginning 

 of this second (male) condition, the stigmas have not quite withered, but are still 

 receptive, so that an insect alighting on them may still bring about cross-pollination, 

 or the fall of pollen from the same flower may automatically effect self-pollination. 

 Looked at with the naked eye, or with a lens, the stigmatic papillae certainly look 

 dried up, but microscopic examination shows that at the beginning of this second 

 stage numerous pollen-grains adhere to them. Should, however, self-pollination 

 take place it is probably ineffective, for ripe fruits containing seeds are rarely found 

 if insect-visits fail owing to unfavourable weather. 



Nectar is secreted and concealed in remarkable cup-shaped nectaries, formed by 

 specialization of the petals. The flowers being pendulous, and the sepals forming 

 a close investment, the secretion is well protected from rain. The nectaries are close 

 to the sepals, while the stamens and stigmas project so far beyond them that some of 



Fig. 12. Hilleborus foctidus, L. (From nature, half schematic.) i. Flower in first (female) 

 condition. 2. Flower in second (male) condition, >fe, Outline of calyx :«, nectaries ; a, immature anthers ; 

 a\ mature anthers ; j, stigma. 



the insect visitors are quite unable to reach them. These content themselves with 

 gathering pollen, plunging into the crowd of stamens after brushing past the stigmas. 

 The insects which are able to suck the nectar, climb over styles and stamens, 

 between the latter and the sepals, till they reach the nectaries, and so always come 

 into contact with the stigmas, and — should the flower be in the second stage — dust 

 themselves with pollen. It therefore follows that pollen-collectors and nectar-suckers 

 alike effect cross-pollination. 



Visitors. — These are chiefly Hymenoptera, of which I observed the 

 following. — 



I. Apis mellifica L. 5, very freq., both po-cltg. and skg.; 2. Bombus terrester L. 

 $, occasional, ditto ; 3. B. lapidarius Z. ?, ditto, ditto ; 4. Anthophora pilipes F. 5, 

 ditto, ditto. Also Diptera. 5. Eristalis tenax Z., po-dvg. 



79, H. viridis Z. (Sprengel, ' Entd. Geh.,' p. 298 ; Knuth, Bot. Centralbl., 

 Cassel, Ivii, 1894.) — The yellowish-green flowers are solitary, or in pairs, and owing 



