Lastly, the three longer stamens alternate with the three shorter ones,
whereas in Lythrum and Oxalis the long and short stamens belong to distinct
whorls. With respect to the absence of the mid-styled form in the case of the
Pontederia which grows wild in Southern Brazil, this would probably follow if
only two forms had been originally introduced there; for, as we shall hereafter
see from the observations of Hildebrand, Fritz Muller and myself, when one form
of Oxalis is fertilised exclusively by either of the other two forms, the
offspring generally belong to the two parent-forms.
Fritz Muller has recently discovered, as he informs me, a third species of
Pontederia, with all three forms growing together in pools in the interior of S.
Brazil; so that no shadow of doubt can any longer remain about this genus
including trimorphic species. He sent me dried flowers of all three forms. In
the long-styled form the stigma stands a little above the tips of the petals,
and on a level with the anthers of the longest stamens in the other two forms.
The pistil is in length to that of the mid-styled as 100 to 56, and to that of
the short-styled as 100 to 16. Its summit is rectangularly bent upwards, and the
stigma is rather broader than that of the mid-styled, and broader in about the
ratio of 7 to 4 than that of the short-styled.
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