Robertson — Flowers and Insects. 157 



pendulous, or nearly so. The flowers are rather inconspicuous 

 and are partly concealed by the leaves, but there is an abun- 

 dance of nectar. The lower petal is quite large. It is notched 

 at the apex and bears a longitudinal groove which terminates 

 in a blunt spur. The spur conceals the nectar, which is 

 secreted by a large gland formed by a union of the two basal 

 processes of the two lower stamens. The stamens are united 

 into a tube enveloping the pistil, their cone-shaped tips receiv- 

 ing the loose pollen. Near the tip, the style is bent aside so 

 that the stigma is placed in the groove of the lower petal. 

 When a bee lands upon the lower petal, to which it clings, its 

 proboscis is guided by the groove to the nectar at the base. 

 The stigma is first touched and thrown upwards and back- 

 wards, a movement which disturbs the loose pollen and causes 

 a downpour. Although there is evident adaptation for cross- 

 pollination, and I have not seen any evident modification for 

 securing spontaneous self-pollination, still the inconspicuous 

 flowers, partly concealed by the leaves, the shady situations 

 in which the plant grows, as well as the apparent infrequency 

 of insect visits, lead me to suspect that spontaneous self-pol- 

 lination may occur. On May 7th, I saw the flowers visited 

 for nectar by a single female of Augochlora pura Say. 



EuoNYMUs L. — The flowers have freely exposed nectar. 

 They are usually perfect, but in England, Darwin (5) found 

 E. europaeus to be polygamous and trioicous, about one-half 

 of the plants having all of the flowers pistillate. In the Tyrol 

 Schulz (12) found this species to have perfect flowers in most 

 cases, less frequently andro- or gynomonoecious. Of several 

 thousand plants, he observed but two or three with only pistil- 

 late or staminate flowers. 



Among the more or less fanciful types of floral mechanisms 

 which Delpino (4) recognizes are the Tipo ramnaceo and Tipo 

 melantino. He regards both as adapted to the larger flies. 

 The former contains E . europaeus^ latifolius, and japonicus; 

 the latter contains E. verrucosus^ with lurid color and offen- 

 sive odor. In England, Darwin saw E. europaeus visited by 

 many Diptera and some small Hymenoptera. In Germany, 

 Miiller (3) saw it visited by twelve flies, mostly Syrphidae and 



