PART III. | THE MECHANISMS OF FLOWERS. 223 
place, and cross-fertilisation may also occur by the outer stamens 
of one flower coming to stand over the stigmas of the next. 
Fia. 73.—Spirea ulmaria, 1. 
1.—Young flower. 
2.—Older ditto. 
Visitors: A. Hymenoptera—(a) Apidew: (1) Apis mellifica, L. 9, ab., 
.; (2) Andrena Coitana, K. ?, ¢.p. ; (3) Prosopis communis, Nyl. 9, f.p. ; 
@) Chryside: (4) Chrysis ignita, L.; (5) Elampus auratus, Wesm. ; (6) 
 Hedychrum lucidulum, F. (I have never seen Chryside eating pollen, and so 
_ I suppose that these species were attracted by the flowers without finding any- 
thing useful in them). B. Diptera—(a) Syrphide: (7) Eristalis horticola, 
Deg. (Sld.) ; (8) E. arbustorum, L. ; (9) E. nemorum, L. ; (10) E. tenax, L. ; 
_ (11) E. sepuleralis, L.,—all eating pollen, in great numbers ; (12) Volucella 
jombylans, L. ; (13) Helophilus floreus, L. ; (14) Syritta pipiens, L., all f.p. ; 
_ (0) Muscide : (15) Anthomyia sp. C. Coleoptera—(a) Nitidulide : (16) Cy- 
chramus luteus, F.; (b) Dermestide: (17) Anthrenus pimpinelle, F. ; (c) 
Lamellicornia: (18) Trichius fasciatus, L.; (19) Cetonia aurata, L.,—both 
eeding on the tissues of the flower ; (d) Mordellide : (20) Mordella aculeata, 
u.; (e) Cerambycide: (21) Pachyta 8-maculata, F, (Sld.); (22) Strangalia 
uttenuata, L.,—both feeding on the anthers. 
131. Sprr#A FILIPENDULA, L.—The flowers secrete no honey, 
and are, therefore, visited only by pollen-seeking insects, which, 
Fg wing to the position of the parts, usually alight on the stigmas and 
_ perform cross-fertilisation. The petals are bent backwards and 
ownwards when the flower is fully expanded, and they are attached 
»y such narrow claws that they dip down under the weight of a 
small bee or fly, and are, therefore, unsuitable for a standing-place. 
The stamens before dehiscing are bent far outwards, and in the 
iy 
3 entre of the flower nine to twelve broad bifid styles spread out into 
