354 HUTCHINSON'S POPULAR BOTANY 



deeper colour than the rest of the perianth. The crown of the Passion- 

 flower (Passiftora), which in some species is single, in others double, is 

 split up into narrow threads which Fritz Miiller, a naturalist who has 

 given much attention to the mechanism of floral organs, believes to be 

 of service in detaining small insects in the lowest chamber of the flower, 

 and keeping them caged for humming-birds, the chief pollinators of many 

 species of Passiflora. 



In the White Dead-nettle (Lamium album} there is a circle of hairs in the 

 narrow part of the corolla-tube, near the base, which serves the purpose of 

 excluding flies and small bees from the nectar, these being useless to the 

 plant. The corona of our beautiful bog-flower, Grass of Parnassus 

 (Parnassia palustris), is very interesting. It consists of five scales (the 

 nectaries) terminating in hairs, each of which is surmounted by a yellow 



FIG. 435. ANTHERS AND THEIR DEHISCENCE. 



(a) Longitudinal, (6) transverse, (c) valvular, (d) porous dehiscence ; (e) cross-section of stamen of a Lily 

 (/) stamens of a Milkwort (Polygala erioptera). 



glandular body, which has all the appearance of a drop of fluid. Even flies 

 are deceived by these shining knobs, mistaking them for drops of honey. 



We come now to the stamens or male organs, which are known col- 

 lectively as the andrwcium. The forms of these, like the forms of the calyx 

 and corolla, vary considerably. Bearing in mind what has been said 

 already about the stamens in connection with cohesion and adhesion, 

 there is really little else to be acquired. 



It is instructive, however, to notice the diversities of form and 

 mechanism which the andrcecium presents, and which are usually connected 

 with that most important function, the scattering of the fertilizing meal 

 or pollen. Thus, in the Grasses (Graminese) and Plantains (Plantago) whose 

 pollen is carried by the wind, the anthers swing loosely on their connectives, 

 and so assist the wind in its useful labour they are versatile ; while in cer- 

 tain species of Sage (Salvia) the connective forms a curved bar or lever, and 



