stigma

As nouns the difference between stigma and geitonogamy

is that stigma is stigma (mark of infamy) while geitonogamy is (botany) transfer of pollen grains from the anther of a flower to the stigma of another flower of the same plant.

As a noun stigma

is stigma (mark of infamy).

As an adjective protandrous is

(label) exhibiting protandry.

In botany terms the difference between stigma and protogynous

is that stigma is the sticky part of a flower that receives pollen during pollination while protogynous is whose female parts (archegonia) mature before the male parts (antheridia) release their spermatozoids .

As a noun stigma

is a mark of infamy or disgrace.

As an adjective protogynous is

exhibiting protogyny.

As nouns the difference between stigma and chemocyanin

is that stigma is stigma (mark of infamy) while chemocyanin is a plantacyanin, extracted from the stigma of the lily, that induces pollen tube guidance.