NOTES ON POLLINATION. S 



the beetles iind small flies often alight on tlie petals and so fail to 

 recompense their host, but a frequent guest, Anthophora urbana, 

 always alights in the center and makes a complete circuit of the 

 flowers in search of honey. I have seen small butterflies work at 

 the flowers in the same systematic way. 



PoTENTiLLA GRACILIS, Dougl. This larger and more showy 

 species resembles the above in its method of pollination, but varies 

 from it in some interesting particulars. The flowers open in the 

 morning with mature stigmas, but the flowers of the previous day 

 rarely retain their j^etals the second day, so there are few, if any, 

 conspicuous flowers to furnish pollen during these early hours. In 

 fact, the newly opened flowers seem to provide little honey at this 

 stage, and insect visits are few until near noon, when the four circles 

 of anthers begin dehiscing. Guests now become numerous, large 

 and small flies, hive-bees, Osmia Calijornicus, Ammophila, Melis- 

 sodes, etc., many of them of the most desinible sort. The flowers 

 close rather earh' in the afternoon and whenever the weather is 

 cloudy. 



PoTENTiLLA ANSERiNA, L., has Solitary and therefore less conspic- 

 uous flowers than the other two species, but the flowers retain their 

 petals much longer. The anthers begin dehiscence soon after the 

 flower opens, and from the first assume a nearly erect position, so 

 that self-pollination is possible. I was not able to observe this 

 species so carefully as the others, but I think, its flowers secrete less 

 honey and have fewer guests. I have seen bees on them. 



HoRKELiA BoLANDERi, Gray, var. Parryi, Wats., was very abun- 

 dant throughout the summer. The introrse anthers and the stigmas 

 seem to me to mature simultaneously, but not to come into contact. 

 Honey is secreted by a ring of tissue below the stamens, and the 

 bases of the filaments, together with the calyx, may exclude it to 

 some extent from small beetles and flies. The flowers are thronged 

 with guests of various sorts. Sand- wasps are specially numerous, 

 and there are large flies and many kinds of bees. The insects in 

 making the circuit of the honey-secreting ring must effect close- as 

 well as cross-pollination. 



