In some plants the stamens are perfected before the pistil; these are called proterandrous, as in Ranunculus repens, Silene maritima, Zea Mays.
The flower is termed proterandrous or proterogynous according as anthers or stigmas mature first.
Xenogamy is of course the only possible method in diclinous plants; it is also the usual method in monoclinous plants, owing to the fact that stamens and carpels often mature at different times (dichogamy), the plants being proterandrous or proterogynous.
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