33 



the same, I always expect to find less specialized insects on 

 the crowded flower." 



\_yhe relation between conspicuousness and pollination of 

 flowers is noticeable in some flowers, as in Lysimachia vul- 

 garis of which two forms occur , one in which the parts of the 

 flower are larger and colored more intense; in this case self- 

 pollination rarely occurs; but a form which grows in shaded 

 places has smaller and less conspicuous flowers and these are 

 seldom visited by insectaJuAn equally instructive lesson is 

 afibrded by the small heart's ease {Viola tricolor). The 



FIG. 18. 

 Fig, 18. Nectaries. I. to tlie left, Hellebore iUellehorua viriMa). II. Colum- 

 bine {A^wUegia vulgaris) . III. Violet ( Virila oAorata) . I. and II. three times en- 

 larged. I. to the right, Parnassus (Panias8ta palusCrte). s. nectary, d. portion 

 where nectar is secreted ; f . stamen, b petal. 



species has two varieties. The large flowered variety with 

 conspicuous flowers, variety vulgaris, which has given rise to 

 our pansy, is frequently visited by bumble-bees and other 

 insects. In fact there is no occasion for self-pollination since 

 insects carry pollen from one flower to another. The variety 

 arvensis on the other hand is smaller and is a weed in gardens 

 and fields. It is seldom visited by insects. Yet in both 

 cases the spur of the lower petal contains the honey. Bhin- 

 anthus crista galli variety major is abundantly visited by 

 insects while the vartety minor is not. It follows from this 

 that colors are important in pollination.^ 



