524 THE FERTILISATION OF FLOWERS. [PART IIT. 
Orv. SALICINEZ. 
378 a. SALIX CINEREA, L.; 3780. S. cApREA, L.; 378c. S. 
AuRITA, L., etc.—In spite of the simplicity of their flowers, which 
differ little from the anemophilous flowers of the poplar, willows 
possess special modifications which bring them greater variety of 
insect-visitors in the first sunny days of spring, and insure them 
abundant cross-fertilisation. These are: 1, the union of many 
flowers on one inflorescence, which is not only more conspicuous, 
but more easily and quickly sucked than so many single flowers ; as 
in all other diclinous entomophilous plants, the male flowers are 
more conspicuous than the female ones, owing in this case to the 
bright yellow colour of the anthers; 2, the development of the 
flowers in many Salices before the leaves, which renders the flowers 
conspicuous among the bare twigs in spite of their want of coloured 
envelopes ; 3, the large store of honey and pollen; and 4, above all, 
the early period of flowering, which leads many bees, especially 
many species of Andrena, to resort almost exclusively to willows in 
search of food for their young. These characters, of which the 
only one probably that has been developed in direct reference to 
insect-visits is the secretion of honey, have so far insured cross- 
fertilisation that the plants can well afford to dispense with the 
power of self-fertilisation. Most diclinic entomophilous flowers 
(Asparagus, Ribes nigrum, Lychnis vespertina, etc.) seem to have 
become diclinic by degeneration of their formerly hermaphrodite 
flowers, but Salix seems to inherit its diclinic condition from the 
oldest phanerogams, which were diclinic and anemophilous. 
Visitors: A. Hymenoptera—(a) Apide: (1) Apis mellifica, L. $,s. and 
c.p., very ab. ; (2) Bombus fragrans (Pall.), K. 2; (3) B. hortorum, L. 9; (4) 
B. lapidarius, L. 9; (5) B. pratorum, L. 9; (6) B. Scrimshiranus, K. 9; (7) 
B. terrestris, L. 9, Nos. 2—7 s.; (8) Osmia rufa, L. ¢, s.; (9) Nomada 
succincta, Pz. 9 ¢, very ab. ; (10) N. lineola, Pz. ¢; (11) N. varia, Pz. ¢, 
ab. ; (12) N. Lathburiana, K. 9 ¢, ab. ; (13) N. ruficornis, L. 9 ¢, very ab. ; 
(14) N. signata, Jur. ; all the species of Nomadas. ; (15) Colletes cunicularia, L, 
? d, cp. and s., in hundreds ; (16) Andrena albicans, K. ? ¢, very ab. ; (17) 
A. albicrus, K. 9 g; (18) A. apicata, Sm. 9 ; (19) A. argentata, Sm. (= gracilis, 
Schenck) ?, scarce, ab. ; (20) A. atriceps, K. (= tibialis, K.) 9 ¢; (21) A. 
chrysosceles, K. ¢; (22) A. cineraria, L. 9 ¢, ab. ; (23) A. Collinsonana, K. 
?; (24) A. connectens, K. 9, scarce ; (25) A. dorsata, K. 9 ¢, ab. ; (26) A. 
eximia, Sm. ¢; (27) A. Flesse, Pz. 9, rare ; (28) A. fulvicrus, K. ? g, ab. ; 
(29) A. Gwynana, K. 9 g, ab.; (80) A. helvola, L. 9 ¢; (31) A. nana, K. 
2 d; (32) A. nigroenea, K. 9 ¢; (83) A. nitida, Fourc. ¢; (34) A. parvula, 
K. ¢; (85) A. pilipes, F. ¢; (36) A. pratensis, Nyl. (= ovina, Kl.) ? g, ab. ; 
