FLOWERS WITH CONCEALED NECTAR 113 



As I have pointed out (' Bliitenbesucher,' I, pp. 16-17), ^^ot only do the flowers 

 of this class present a considerable advance on those of the previous group, but their 

 visitors also attain a distinctly higher level of specialization with regard to pollination 

 than do the visitors of flowers with partly concealed nectar. The less intelligent 

 short-tongued insects, finding it more difficult to get at nectar which is completely 

 concealed than that which is more or less exposed, are much less important here than 

 in the two preceding classes. Long-tongued insects, on the other hand, visit these 

 flowers far more. 



The honey-bee may almost everywhere be observed sucking the flowers 

 belonging to this class : its proboscis (6 mm. long) conveniently reaches the nectar 

 concealed in the base of the flower, the position of which it quickly discovers. Its 

 nearest relatives, the humble-bees, also appear in swarms as visitors, and parasitic 

 humble-bees eagerly seek out the abundant though hidden nectar, which they can 

 reach without trouble, with the help of their long proboscis. The other long-tongued 

 bees join them in this quest. 



Since the nectar is usually concealed at a depth of only a few mm., it is easily 

 reached by short-tongued bees and long-tongued wasps, as well as by the Bombyliidae 

 and Syrphidae among the Diptera. The nectar, owing to its deeper position, can 

 also be more conveniently sucked up by Lepidoptera than that of flowers belonging 

 to the preceding classes. 



This is more difficult for short-tongued flies (Muscidae and others) and wasps. 

 For the same reason beetles are even more infrequent visitors : those that do occur are 

 usually small forms, with slender bodies, enabling them to creep right into the flower, 

 where they get at the nectar, without conferring any benefit. The coleopterous 

 visitors are sometimes pollen-eating beetles, which only occasionally effect pol- 

 lination. 



Some flowers of this class are specially interesting, as being visited by definite 

 species or groups of insects. 



Wherever Lythrum Salicaria grows, for example (see p. 95), the bee Cilissa 

 melanura Nyl. is found upon it as a guest, and indeed scarcely visits any other plant. 



Symphoricarpos racemosus is in some districts almost exclusively visited by wasps, 



while Scrophularia nodosa is everywhere a well-marked wasp flower, as are Cotone- 



aster vulgaris and Lonicera alpigena (according to Herm. Miiller's observations in 



the Alps). These wasp flowers will be more fully described when hymenopierid 



Jlowers are dealt with (cf. pp. 119-20). 



Veronica Chamaedrys and a few other species of the same genus are hover-fly 

 flowers, as the delicate mechanism of pollination is here only properly brought into 

 action by flies of the kind (see Floral Class, Fb, pp. 135-6). 



Not a few flowers conceal the nectar so deeply that they form a transition 

 between classes C and H, so that they may be designated by the symbol C H, 

 e.g. Rubus Idaeus and saxatilis; Euphrasia officinalis, salisburgensis, and minima; 

 Goodyera repens. The following belong to CHb : Polygala comosa and alpestris, 

 Polemonium caeruleum, Vaccinium Vitis-Idaea and uliginosum, Calluna vulgaris. 

 Saxifraga oppositifolia belongs to the transitional stage CL : Hermann Miiller 

 ('Alpenblumen,' pp. 25 and 31) includes the following in CF : Oxalis Acetosella, 

 Pyrola uniflora and rotundifolia. 



DAVIS T 



