- PART IIL. | THE MECHANISMS OF FLOWERS. 389 
ia inoperative, we can easily comprehend how in Hottonia palustris 
tha application of pollen from a long-styled flower to a long-styled 
stigma on another plant has retained its full efficiency. 
4 Androsace Vitaliana, K.S., is dimorphic (Treviranus, No. 742; 
- Darwin, No. 167). 
The Alpine species of Androsace (A. septentrionalis, L., A. 
Chamejasme, Host., A. obtusifolia, All., etc.) are homogamic, and 
_ visited chiefly by Diptera, but to some extent by Lepidoptera and 
- small bees; in absence of insects they are self-fertilised (No. 600, 
figs. 140, 141). 
___-* Species of Cortusa fertilise themselves, according to Treviranus, 
by the style bending back towards the anthers (742). 
. Dionysia, Fenzl., is dimorphic according to Kuhn (399). 
4 The Alpine species of Soldanella are adapted for bees by the 
pendulous or inclined bell-shaped flower, the lilac or violet colour, 
the position of the anthers close around the style, and the more 
or less complete protection of the honey from small insects by 
_ means of the anthers and appendages of the corolla (609,° figs. 
_ 146-148), 
290. LysIMACHIA VULGARIS, L.—The following varieties of 
this plant occur near Lippstadt: (@) on sunny embankments, a 
conspicuous form which is never or only rarely self-fertilised ; (0) in 
shady hollows, a less conspicuous form which fertilises itself 
regularly ; (c) transition forms in spots intermediate in character, 
¢g.on the banks of ditches exposed to the sun. In the form (a) 
the petals are dark-yellow, red at the base, recurved, expanding 
_ widely, about 12 mm. long and 6 mm. broad on an average, and 
_ the filaments are red near the end; the style projects. several 
millimetres ‘beyond the tallest anthers, so that in case of insect- 
' visits, cross-fertilisation takes place regularly, but in absence of 
insects, self-fertilisation cannot easily occur. In (0) the petals are 
 light-yellow and of one colour throughout, 10 mm. long and 5 mm. 
_ broad on an average, not spreading out so widely, but for the most 
part diverging obliquely upwards; the filaments are greenish-yellow; 
the style is of the same length as the two inferior and longer 
stamens, so that in absence of insects self-fertilisation always 
occurs. (c) The intermediate forms differ from (0) either (1) by the 
1 This reasoning, however, is directly opposed to other cases, such as that of — 
| _ Linum grandiflorum, in which the long-styled form is quite unproductive with 
pollen from another long-styled flower, although from the position of the anthers it 
is regularly conveyed to the stigma (No. 167, chap. vi.). ; ‘ 
