Let’s Talk About Plant Sex
At a certain stage in every plant’s life cycle, all the plant wants to do is get busy and make lots of babies so its genes carry on. But how do objects rooted permanently in the ground have sex?
When it comes to plants and sex, there is a lot to talk about. From mimicry, to knocking their pollinator partners senseless, to perfect flowers with all the right pieces in all the right places, to seductive sirens that draw their pollinators in, flowering plants display tremendous diversity in their methods of reproduction. Plants have active sex lives, as this article is about to prove, starting with a little talk about plant parts.
An Anatomy Lesson
Before jumping right into bed, let’s review a bit of the reproductive morphology of our flowering friends. The stamen is the male pollen-producing reproductive organ and is comprised of the stalk-like filament and the anther, which contains the pollen. The carpel, or pistil, is the female reproductive organ and is made up of the stigma, style, ovary and ovule. If it all stopped there, this would be a simple insert tab A into slot B kind of scenario…but Mother Nature is much more adventurous than that.
Some flowers are hermaphroditic, which means they have both male and female parts. These flowers are referred to as perfect. A flower missing either the male or female parts is referred to as imperfect.
Plants may also have flowers that are complete or incomplete. If a flower has sepals, petals, pistils and stamens, then it is a complete flower. If any of the aforementioned pieces of anatomy are missing in a flower, then it is known as an incomplete flower. Imperfect flowers are always incomplete, but incomplete flowers may or may not be imperfect, just like all squares are rectangles, but not all rectangles are squares.
Plants can also be classified as monoecious or dioecious. Monoecious plants have separate male and female flowers on the same plant. Corn, cucumbers and figs are monoecious. Dioecious plants have male and female flowers on separate plants. Holly, kiwi and hemp are examples of dioecious plants.
How Plants Do It
Sex with one’s self is all fine and good, but we all know sex with a partner or, in some cases, many partners, is better! A plant’s goal in life is to pass on its genetic materials by any means necessary, which includes both sexual and asexual reproduction. Sexual reproduction is the fusion of two gametes: the pollen and the ovule. Asexual reproduction is the formation of new plants by any other means, which can include vegetative cloning (rooting a cutting from a plant), or fragmentation—dividing a plant into two or more pieces.
Plants can also reproduce on their own in some cases. Stolons, which are modified plant stems that run along the ground, occasionally lay down roots of their own that develop into separate plants. Strawberry plants are a perfect example. Also, plants that form bulbs or tubers over time will develop bulb-lets and buds, tiny structures that eventually mature into fully formed tubers and bulbs. These eventually give rise to a new plant.
Now to get into the down and dirty side of plant reproduction—when plants need a little help. To attract a pollinator, plants have evolved several strategies. Some flowers produce a strong fragrance, like a pheromone perfume, that travels on the wind to attract pollinators, sometimes from as far as a mile away. Some have specific prey. For example, Mexican stanhopeas produce a powerful fragrance designed to lure only a specific species of bee to their location.
Other plants use a combination of fragrance and a pollination tactic known as mimicry, where they attract bees by producing a scent that mimics the scent of a female bee. Some plants go even further—the lip of the Ophyris apifera orchid flower strongly resembles a female bee so that the male bee confuses it with a female bee and tries to have sex with the flower. Pollen transfer occurs during the ensuing interaction.
While for humans, consent is paramount, in the plant world, naivety and non-disclosure run rampant. Some flowers actually knock their pollinator senseless (the first episode of Showtime’s Californication comes to mind). Or consider the male flowers of the orchid genus Catasetum, which employ a hair-trigger activated pollen release mechanism that forcibly attaches pollen sacs onto an unsuspecting bee’s back. The force with which the pollen smacks the bee leaves it flying off in a daze. The bee then heads for safety, where it finds a female Catasetum flower.
There was a period of human history where Royal families practiced inbreeding to solidify power, or as an act of diplomacy. This caused all sorts of issues, including hemophilia and a host of other disorders stemming from the expression of recessive traits due to a lack of genetic diversity. For this reason, inbreeding is frowned upon where humans are concerned, but in the plant kingdom, it is prevalent and often used by growers and biologists to stabilize particular traits in a species.
A phenomenon known as a hybrid swarm is a population of individual plants that are all hybrid offspring, consisting of primary hybrids between the original parent species, various generations of backcrosses between the hybrids and parent species, and crosses between the resulting primary hybrids. This inbred plant orgy causes a blur in the integrity of the parent species. Essentially, with limited starting genetic diversity, compounded by extensive inbreeding, backcrossing and just plain promiscuity, the traits that differentiate species from hybrids get blurred.
Next time you hike into a field of wildflowers and start picking, you may want to consider using protection, now that you know how wanton plants can be!