It’s springtime, so those of us with allergies might have noticed plants getting all animal planet with our sinuses. Seems most plants are pretty lose with their pollen, but when it comes to procreation, they’re very particular. So how do plants swipe right on a match?
First base is geography. Plant breeders can take related plants from different regions, play some Barry Manilow, and cross them in a green house yielding new varieties. But under normal conditions, plants have to live and thrive in the same environments to cross.
Second base is timing. To our dismay allergy season is a season not a day. That’s because different plants flower at different times. They respond to environmental cues like day length and temperature and flower at the time that will yield the maximum chance of survival and success for their offspring. The timing differs depending on the plant and the method of seed dispersal/germination. So even in plants, equivalent levels of maturity are necessary for a fruitful relationship.
Third base is anatomy. For some plant species, male and female reproductive parts are found on different plants (sound familiar). I’ll spare you the analogy, but for many species, both genitalia appear on the same plant. In some cases they’re right up next to each other within the same flower. The location of plant privates determines whether plants are more likely to breed with their neighbors or themselves.
Plants are actually pretty content with pollinating themselves, and some almost exclusively self-fertilize. These loners like rice can be a real pain for breeders hoping to cross different varieties. On the other hand, corn man parts, called tassels, stick right out of the top of the plant. Wind blows the pollen from the tassels and it lands on the silky hairs that stick out of the ears of neighboring plants as much as 200 feet away
Home runs require chemistry. Assuming our gentle-pollen and lady-ovule live in the same zip code, are age-appropriate, and are serendipitously brought together (totally not by online dating), there’s still got to be chemistry. And I’m not being cute here, I’m talking about literal chemistry. In order for fertilization to occur, pollen has to produce a straw-like appendage called the pollen tube which delivers the sperm to the egg. Pollen tube growth is guided by chemicals called chemoattractants which are produced by the ovule.
Aw scent of a woman! The molecules that ovules use to lure pollen tubes had been previously identified. Just last month, two studies published in the prestigious journal Nature uncovered the male receptors that recognize their female partners. Why are these breakthroughs important? If we can figure out what prevents different species from crossing, we might be able to create inter-species mixes (like an actual “grapple” or the blue raspberries my brother keeps pushing for).
Happily ever after. So that’s what happens when two plants love each other very much. For a real R-rated experience, check out these absolutely incredible videos of plant and insect mé·nage à trois encounters.
- Flowers trick male wasps into thinking they are female wasps. A BBC production.
2. Flower requires bee “vibrations” to release pollen. Also a BBC production.
For scientist readers, here are the less fun but fascinating nature papers: