Protogynous: (proh-tuh-jahy-nuhs)
1. Adjective
2. BOTANY – (of hermaphrodite or monoecious plants) or relating to a flower in which the shedding of pollen occurs after the stigma has stopped being receptive, having female sex organs maturing before the male
Protandrous: proh-tan-drus
1. Adjective
3. BOTANY - (of hermaphrodite or monoecious plants) or relating to a flower maturing the anthers before the stigma
All plants have an innate drive to propagate their species or risk becoming extinct. All plants have developed specific ways maintain their existence. Oaks have acorns, zinnias self-pollinate and dropped seed grows the next season, seeds from fallen tomatoes will sometimes sprout in the vegie garden. The flowers on plants may contain only male reproductive parts, only female reproductive parts, or both. Timing is everything. Just like in humans, where eggs must be “ripe and ready” for sperm to complete fertilization, the reproductive parts of a plant must be ready to “give pollen” to the “ready” eggs in order for fertile seeds to develop: the pits of fruit, seeds in a sunflower, etc.
The two terms listed above are a very specialized fertilization process that inhibits self-pollination in order to maintain the genetic diversity of the seeds and reduce invasive habits.
Protogynous flowers begin life as wholly female with the ovaries briefly available for pollen. However, there is no pollen available at that time. Over a period of time the ovaries drop and then the male pollen develops. In other words, the flower changes completely from female to male over the period when the flower is open. Because the reproductive parts occur in sequence instead of simultaneously, self-fertilization is non-existent or rare.
Protandrous flowers begin life as wholly male with lots of pollen available to bees. These plants are essential to attract pollinators early in the season to assist with pollination of other plants that require lots of pollinator activity to produce heavy fruit crops. The male flowers then transition to wholly female flowers. Scientists have timed the transition process in several species. It happens within hours. Again, self-fertilization is rare or non-existent.
Examples of plants with protandrous flowers are Ivy (thank goodness that plant doesn't self-seed), salvias, pecans, mints, legumes, carrots, and some wind-pollinated plants, including some grasses.
Examples of plants with protogynous flowers are arum lilies, some wind-pollinated plants including some grasses, and avocado. COOL FACT: avocado has both protandrous and protogynous varieties. Growers must plant both in their orchards to get good crops and homeowners may get very few fruit with only one tree. Crop production is solely dependent on having available pollen when the female parts are ripe.