120 THE FLOWERING PLANT. 
the outer ones irregular and much larger than in the inner 
ones. 
The most closely related flowers often differ remarkably in 
character, and this is correlated with differences in pollination. 
Compare, for instance, the common mallow (Malva sylvestris) 
and the dwarf mallow (M. rotundifolia). The flower of the former 
is much the larger, and the numerous stigmas form a tuft above 
the ends of the monadelphous stamens (cf. p. 95). It is insect- 
pollinated. The latter has much smaller flowers, and the stigmas 
and stamens intertwine, favouring self-pollination. A similar 
pair is found in the large-flowered, proterandrous rose-bay willow 
herb (Epilobium angustifolium), and the small-flowered willow 
herb (EZ. parviflorum), the stamens and stigmas of which mature 
simultaneously. The following table! compares, in this connec- 
tion, four of our native wild geraniums. 
Blue Meadow Mountain Dove’s-Foot Small-Flowered 
Geranium Geranium Geranium Geranium 
(G. pratense). | (@.pyrenaicum). (G. molle). (G. pusillum). 
Flower . : Large. Small. Smaller. Smallest. 
Proterandry .| Complete. Partial. Partial. Slight. 
Pollination .| Never self- Sete Often self- | Generally self- 
insect- 
Monocotyledons are remarkable from the fact that, although 
they include some of the minutest wind-pollinated forms (sedges, 
grasses, and rushes), yet, on the other hand, many of the most 
conspicuous flowers are found among them. Not only is the 
calyx frequently as bright as the corolla, eg., in lily, tulip, and 
hyacinth, but also stamens may become petaloid, as in orchids 
(cf. p. 88), and the three styles of zis are in the same condition. 
Their bracts also are frequently petaloid, as In many orchids and 
hyacinth, while in some exotic arums the enlarged spathe plays 
the part of a corolla. In many arums, too, the fleshy axis of the 
spadix compensates for the lack of perianth. 
Odour.—This varies according to the visitors required. Jra- 
grant flowers attract bees, butterflies, moths, and higher insects 
generally, while more rarely jfatid odours are given out with the 
view of enticing flies. Many flowers which to us appear scentless 
are probably not so to insects, which seem to be gifted with 
unusually keen powers of smell. There can be no doubt, for 
1 Modified from Lubbock. 
