PENTSTEMON GRACILIS. 73 



of diluted Karo on the anthers without noticing its presence, and went 

 directly to the anthers as usual. Another twice visited a flower with a 

 drop at the right corner of the corolla mouth, and rubbed the anthers without 

 discovering the sirup. Halictus pulzenus entered flowers with Karo on the 

 anthers as it did normal ones, that is, upside down. It walked through 

 one drop, turned around, and sipped it up before flying away. Vespa 

 germanica visited every flower on the stalk except those with the Karo 

 drop. Osmia melanotricha entered a flower with Karo at the right corner 

 of the mouth, straddling the staminode in the usual manner, but before 

 reaching the nectar turned around and came out at the left corner. 

 Bombus juxtus almost entered such a flower, but suddenly flew to the next 

 one. 



PENTSTEMON GRACILIS. 



NORMAL POLLINATION. 



Habit and structure. — This is the smallest flowered species of Pent- 

 stemon found in the Pike's Peak region. The corolla-tube is narrow and 

 comparatively long, 1 to 2 cm., and the limb extends at right angles to the 

 tubular portion. The racemes are erect, the color varying from delicate 

 pink to pale blue. It grows on warm slopes and blooms earlier than the 

 other species in the locality, and is sought particularly by various species 

 of Osmia. 



Behavior. — Osmia bruneri and pentstemonis push the head into the 

 corolla-tube, the anthers and stigma rubbing against the hairs on the 

 dorsal surface of the thorax as the bee sucks nectar. 0. phaceliae rests 

 on the lower lip, and then enters the flower in a normal position. Its 

 hind legs hang over the lip and the front pair rest in the corolla-tube. 

 It goes from one flower stalk to the next and enters flowers at about the 

 same level, in preference to visiting all the open flowers on one stalk. The 

 same flower is visited repeatedly by different individuals and sometimes 

 one bee returns several times. Prosopis elliptica enters in the normal 

 position and turns so that it either stands upside down or sidewise within 

 the corolla while collecting pollen. Halictus (Chloralidus) sp. lands on 

 the lower lip in the normal position, and then turns upside down, hanging 

 suspended from the upper lip. The tip of the abdomen touches the outer 

 pair of anthers as it scrapes pollen on to the hind legs. 



Bombus juxtus lands, thrusts its head in and places its front legs around 

 the two outer lobes of the lower lip as it sips, the hairs on its head rubbing 

 against the stigma meanwhile. It enters the flower upside down as well 

 as in the normal position. This bee visited pink and blue flowers without 

 discriminating between the two. In one plant with unusually small flowers, 

 it could not get its head into the corolla-tube. However, it inspected 

 these and tried to enter, even splitting the corolla-tube in the attempt. 

 B. juxtus did not accumulate the heavy pollen loads exhibited by B. bifarius. 

 The latter pushes its ligule into the flowers for nectar, the recurved part 

 of the lobes extending past the thorax to the base of the abdomen. As it 

 sips, the anthers rub against the dorsal side of the thorax. Most of the 

 individuals carried heavy pollen loads on their legs, but they were not col- 



