38 
HOW PLANTS EMPLOY INSECTS TO WORK FOR THEM, 
corolla divided and spread open in Fig. 34) has a short style, which brings the 
two stigmas up to near the middle of the tube of the corolla. The sort that 
shows the stigmas projecting (as in Figs. 35 and 36) has the siyle long enough to 
bring them up just to the place which the anthers occupy in the other flower; 
but its anthers are placed as low down in the tube as the stigmas are in the first 
flower. The little Partridge Berry of the woods has its flowers of two sorts, on 
the same plan : and among garden flowers it may be seen in Primroses. But it 
is to be noted that this plan occurs only in flowers that are frequented by insects. 
78. In the Houstonia , small insects, feeding by a proboscis, passing from flower 
to flower, take from the high-stamened one (Figs. 33, 34) some pollen upon the 
face, as it is brought down close to the orifice of the corolla when the proboscis 
is thrust to the bottom for the nectar there. When the insect passes to another 
flower of the same sort, it merely gets its face smeared with a little more pollen. 
But when it visits a long-styled flower (such as Figs. 35, 36) and brings its head 
down to the orifice, it will apply some of this pollen to the stigmas, which are 
exactly in the position to receive it. So the high anthers are to fertilize the high 
stigmas. How about the low stamens and low T stigmas, when the insect flies from 
a flower of the second sort to one of the first, as it is quite as likely to do? 
Why, the insect’s proboscis, as it explores that flower, gets dusted with the pollen 
of the low anthers, and this pollen is neatly carried and applied to the similarly 
placed stigma of the other kind of flower. So much for dimorphous flowers. 
There are even 
79. TrimorphoilS Flowers, that is, perfect flowers of three sorts arranged to co- 
operate in this way. One case at least was discovered by the most sagacious 
investigator of this whole class of subjects (Mr. Darwin), in a kind of Loosestrife 
( Lythrum Salicaria ), and there is something nearly like it in another bog plant of 
the Loosestrife Family, Nescea verticillata. There are three lengths of style and 
three lengths of stamens, two of the latter in each sort of flower, the stamens 
being in two sets. Bees suck the flowers of this Loosestrife. In doing so, the 
longest stamens rub their pollen against the lower and hinder part of the body 
and the hind legs ; the middle-length stamens, between the front pair of legs ; 
the shortest stamens, against the proboscis and chin. When they fly to other 
flowers, the very parts that are dusted with long-stamen pollen rub against the 
stigma of the long style ; those dusted with that of middle-length stamens, 
against the stigma of middle-length style ; those with that of short stamens, against 
