1895.] The Philosophy of Flower Seasons. 109 
more simple open flowers is determined by the early predomi- 
nance of the less specialized bees, and that the late preponder- 
ance of the more complicated closed flowers is correlated with 
the flight of the most specialized bees, leaf-cutters, bumble- 
bees, etc.° 
The Sympetalae (Gamopetalae) consist of flowers with more 
or less deepseated nectar and often with closed complicated 
flowers. They are adapted to bumble-bees or to the more 
highly specialized bees in general, to butterflies or to miscel- 
laneous more or less long-tongued insects. An interesting case 
is that of flowers of Stetronema which are associated with the 
flight of Macropis steironematis, a bee which as far as observed 
depends exclusively upon these flowers for its pollen. The 
wild potato vine (Ipomoea pandurata) is dependent mainly 
upon two bees (Entechnia taurea and Xenoglossa ipomoeae). 
The flowers of ground cherry (Physalis) bloom during the 
flight of two species of Colletes (C. willistonii and C. latitarsis), 
upon which they depend almost exclusively for pollination, 
the little bees on the other hand, obtaining all of their pollen 
from these flowers. The dominant mint family (Labiatae, Fig. 
18, Plate VII] )is principally adaptedto the higher bees, although 
some having degraded irregular flowers with exposed stamens 
are adapted to miscellaneous insects. The figwort family 
(Scrophulariaceae, Fig. 19, Plate VII1)is an evenmoreexclusive 
bee-flower family, most of them being adapted to bumble-bees, 
and appearing late. The earliest species, Collinsia verna, is 
one of the most highly specialized and looks like a papiliona- 
ceous flower. The upper lip and the lateral lobes of the lower 
lip represent banner and wings, while the middle lobe repre- 
sents the keel, and it performs the same function for it con- 
tains the stamens, which instead of lying against the upper 
wall of the corolla, as is usual in the family, are declined across 
the tube. We have observed that most of the Leguminosae 
with declined stamens are adapted to bees with abdominal 
6 The early blooming of the dominant families of Choripetalae, as well as the 
Liliiflorae, must also be explained in part as correlaféd with their woodland 
— their decline being influenced by the appearance of the leaves on the 
