The existence, therefore, of two or three bodies of individuals,
differing from one another in the above more important characteristics, offers
by itself good evidence that the species is heterostyled. But absolutely
conclusive evidence can be derived only from experiments, and by finding that
pollen must be applied from the one form to the other in order to ensure
complete fertility.
In order to show how much more fertile each form is when legitimately fertilised
with pollen from the other form (or in the case of trimorphic species, with the
proper pollen from one of the two other forms) than when illegitimately
fertilised with its own-form pollen, I will append Table 6.33 giving a summary
of the results in all the cases hitherto ascertained. The fertility of the
unions may be judged by two standards, namely, by the proportion of flowers
which, when fertilised in the two methods, yield capsules, and by the average
number of seeds per capsule. When there is a dash in the left hand column
opposite to the name of the species, the proportion of the flowers which yielded
capsules was not recorded.
TABLE 6.33. Fertility of the legitimate unions taken together, compared with
that of the illegitimate unions together. The fertility of the legitimate
unions, as judged by both standards, is taken as 100.
Column 1: Name of species.
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