CASTILLEIA MINIATA. 63 



nectar. Acmaeops longicornis enters the corolla and eats pollen, which it 

 also collects and deposits as it moves slowly about. Selasphorus platycercus 

 visits and pollinates Mertensia as it flies very rapidly from flower to flower. 



In table 47 two lists of visitors are given. The first represents those 

 present during a two-hour period in the midst of the flowering season, the 

 second those for an hour period at the end of the season. In each case 100 

 flowers were under observation. 



During another hour's observation toward the end of the season, 15 

 individuals of Bombus juxtus made 167 visits to 140 flowers. The only 

 other visitors were two wasps that robbed the flowers. 



EXPERIMENTS. 



MUTILATION. 

 Changes of corolla. — The petals were split apart, the corolla made 

 irregular, or the upper petals were removed in various flowers. The only 

 visitors during the period of observation were 4 individuals of Halictus sp., 

 which went to the flowers with the front half of the petals removed. They 

 paid no attention to the exposed stamens and nectar, but pierced the small 

 corolla-tube in the usual place, as when robbing normal flowers. 



CASTILLEIA MINIATA. 

 NORMAL POLLINATION. 

 Habit and structure. — The bracts inclosing the flowers are vermilion 

 in color and arranged in a closely massed spike. As the individual flowers 

 mature they elongate rapidly and take an ascending position. The first 

 pair of anthers ripen while the flower is still very small, about one-third 

 the mature size. The lower lip is much suppressed and serves to open the 

 slit when pulled down. When the anthers are about through dehiscing, 

 the style elongates, grows through the tip of the corolla-tube, and then 

 bends downward. To obtain nectar, visitors must push into the slit of the 

 corolla and reach to the base of the tube. In doing this the head comes in 

 contact with the anthers in young flowers, while in the more mature ones 

 the stigma bends downward so that it rubs the back of the visitor (plate 13). 



Behavior. — Halictus (Evylaeus) sp. transfers pollen from the under part of 

 its abdomen to the receptive stigma as it lands on the green tip of the corolla. 

 It then turns upside down, opens the corolla, and exposes the stamens. 

 With its front legs it scoops out the pollen and places it on the ventral 

 surface of the abdomen. One individual stood with its head at the lower 

 lip of the corolla and took out pollen with its front feet and mouth-parts. 

 A second landed with the head toward the style and tried to open the corolla 

 slit without success; it then turned toward the other end and scraped up 

 the pollen on the outside with its front legs, placing it on the rear legs and 

 abdomen. After turning again, it repeated its unsuccessful attempt to 

 open the corolla, then turned its head downward, and at the lower lip 

 succeeded in opening the corolla. It went into the latter until only the 

 abdomen tip was visible outside the flower. A third bee of this species 

 landed at the tip of the corolla and ate pollen found on the outside. The 

 slit of this flower was inverted, i. e., faced up. The bee walked to the under 



