NOTES ON rOLLINATIOX. 21 



ing a half dozen or more humming-birds among tlieiu.'V Although 

 this species is somewhat later than the other scarlet one, their sea- 

 sons overlap, and the humming-birds often pass from one to the 

 other, but I found no hybrids. The two species are generally similar 

 in their provision for pollination. The flowers of P. Bridgesii are 

 more declined and have a somewhat shorter but a wider tube, so 

 that the hive bee sometimes essays to get the honey. The bee, after 

 much fussing, wriggles into the tube as far asjpossible, but even then, 

 as one can see through the tissue of the corolhi, the tongue does not 

 reach quite to the bottom. The pollen is discharged so slowly 

 through the short curved slit at the apex^of the anthers that it does 

 not tempt the bees, so that this flower comes near to excluding all 

 but the most desirable guests. 



Castilleia affinis, H. & A. Considerable areas of moist land 

 are scarlet w'ith this plant and become resorts for humming-birds. 

 The plant needs no provision for self-pollination. The protruding 

 capitate stigma is sure to be struck by the visiting bird, while the 

 anthers just below in the galea deposit a fresh supply of pollen on 

 its bill. Honey is abundant and pollination is usually effected 

 before the flowers attain their full length, so that the older flow^ers, 

 like the bracts, merely [con tribute to the^general showiness. Thrips 

 are frequently present, and may effect some close-pollination. 



Cordylanthus Nevinii, Gray, flourishes on sunny hillsides 

 among the pines. It flowers in August, and, notwithstanding a 

 slenderness characteristic of the habitat and season, the plant -is 

 fairly conspicuous because of the white tips of the finely dissected 

 leaves and bracts and the prominent lower lip of the corolla. This 

 lip is three or four lines broad, and the flower is one-half inch or 

 more long, but as the corolla tube is less than a line long, the abun- 

 dant honey is accessible to a considerable range of guests. Like 

 Castilleia the flower has a long period for pollination, the essential 

 organs being mature before the flower attains its full growth. The 

 stigmas are exserted but are not so conspicuous as Castilleia. 

 Bombns Californiciis frequentlyj^visits^the flowers, and I have also 

 taken Anthophora urhana and an Ammophila on them. 



Veronica Americana, Schweinitz, abounds along streams and 

 has flower clusters that lastjfrom June to September at least. The 



