The stigmas of flowering plants selectively recognize pollen from the same species in part through biochemical interactions.

References

"A stigma will not react to pollen from another species. Since the physical shape of the pollen grains is so distinctive, it is tempting to think that the recognition between the two is a geometric one analogous to the way that a lock can recognise a key that belongs to it. This may in fact be the case, though if so it is only part of the mechanism of recognition. Other biochemical stimulations and responses also play a crucial part." (Attenborough 1995:96)

Book
The Private Life of PlantsMay 26, 2017
David Attenborough

Living System/s

Organism
Vascular PlantsMagnoliophytaPhylum