2 ANGIOSPERMAE—DICOTYLEDONES 



limb has already completely disappeared, so that only a nectar-cup remains. In 

 Aquilegia there is a similarly formed organ, but much larger, inverted, and curved 

 round at the tip, serving not only to secrete and conceal nectar, but also to attract 

 insects, being therefore brightly coloured. The nectary of Aconitum is shaped 

 much like that of Aquilegia, but it is smaller and provided with a long stalk — the 

 claw of the original petal — which serves to conceal nectar more deeply. The 

 remarkable nectary of Nigella is not connected by any intermediate gradations 

 with the preceding. 



Fig I. Nectaries of some Ranuncidaceae. {Enlarged. From nature.) 

 1. Ranunculus sceUraiits^ L.. 4. Aquilegia vulgaris ^ Z.. 



T^rollius europaeus^ L. 

 3. Helleborus niger, L. 

 K, nectary. ^, limb. 



5, stalk. 



Aconitum Napellus, Z.. 

 6. Nigella arvensis^ L. 

 h, protuberance. 



In not a few Ranunculaceae no nectar is secreted (Clematis, Thalictrum, 

 Anemone, Hepatica). These provide pollen for their insect-guests, as a reward for 

 their work in securing cross-pollination. There are therefore some Ranunculaceae 

 in almost all the flower-classes, as follows. — 



Po or An: Clematis (most species), Thalictrum, Anemone, Hepatica, Adonis, 



Actaea ; 

 E : Myosurus, some sp. of Ranunculus and Batrachium ; 

 EC : Ranunculus, Batrachium, Caltha, Eranthis, Isopyrum, Cimicifuga ; 

 C : Pulsatilla, TroUius, Helleborus ; 

 H : Aquilegia, Delphinium, Aconitum, Atragene, Nigella. 



Species belonging to the flower-classes Po, An, EC, and C, are homogamous 

 or slightly protandrous, more rarely protogynous. In these — owing to the relative 

 position and time of maturation of stamens and carpels — automatic self-pollination 

 is possible in the later stages of flowering should insect-visits have failed. In species 

 belonging to class H — on the other hand — self-pollination is largely prevented by 

 marked protandrous dichogamy, and the visits of bees are often indispensable for 

 fertilization. 



The visitors and pollinators belong to all insect-orders. The white, yellowish- 

 green, and yellow pollen flowers, and the similarly coloured flowers with readily 

 accessible nectar, are visited chiefly by short-tongued insects, especially flies and 

 beetles, more rarely by Hymenoptera, still more rarely by Lepidoptera. The blue 

 pollen flower Hepatica — on the other hand — is chiefly visited and pollinated by 



