PHANKEROGAMIA. 367 
lip usually serving as a resting-place for the insect while it 
thrusts its head or tongue into the corolla. The upper lip 
is frequently arched so as to contain the stamens and style. 
In the Dead-nettle the stigma projects beyond the stamens 
(Fig. 145), so that upon visiting successive flowers the in- 
insect always first pollinates the stigma with pollen from 
D ~. 
. 146.—Flowers of Composites. .A, of Dandelion, showing style protruding 
peek ring of anthers; B, Ef Thoroughwort; C, ditto, vertical section Showing 
style surrounded by anthers; D, style showing two stigmas. All magnified. 
preceding flowers, and then coming in contact with the 
stamens secures more pollen. In many plants with a sim- 
ilar structure the stamens mature before the stigmas are 
ready for pollination, so that in these, while the means for 
cross-pollination are perfect, self-fertilization is rendered 
impossible. 
