FLOWERS AND INSECTS 
135 
FIG. 140. A bee obtaining nectar in the pouch of 
Cypripedium. After GIBSON. 
will result in rubbing some of the pollen upon the stigma, 
and in receiving more pollen for another flower. 
In cases of protandry, as the common fig wort, flowers 
in the two condi- 
tions will be visited 
by the pollinating 
insect, and as the 
shedding stamens 
and receptive stig- 
mas occupy the 
same relative posi- 
tion, the pollen 
from one flower 
will be carried to the stigma of another. It is evident that 
exactly the same methods prevail in the case of protogyny, 
as the fire weed (see Fig. 134). 
The Houstonia (see Fig. 135), in which there are sta- 
mens and styles of different lengths, is visited by insects 
whose bodies fill 
the tube and pro- 
trude above it. In 
visiting flowers of 
both kinds, one re- 
gion of the body 
receives pollen 
from the short sta- 
mens, and another 
region from the 
long stamens. In 
this way the insect 
will carry about two bands of pollen, which come in con- 
tact with the corresponding stigmas. When there are three 
forms of flowers, as mentioned in the case of one of the 
loosestrifes, the insect receives three pollen bands, one for 
each of the three sets of stigmas. 
93. Warding off unsuitable insects. Prominent among 
10 
FIG. 141. A bee escaping from the pouch of Cypri- 
pedium, and coming in contact with the stigma. 
Advancing a little further the bee will come in con- 
tact with the anthers and receive pollen. After 
GIBSON. 
