Plant Sexuality
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Volume 4 (Number 4) Winter 1996

Plant Sexuality & Political Correctness
© W.P. Armstrong (Updated 7 May 2015)

  • Is Polygamy Legal Within The Kingdom Of Plants?
  • How Do Plants Practice Safe Sex With Other Plants?
  • Can A Plant Be Unisexual? How About Bisexual?
  • Why Is The Term "Deflowered" Politically Incorrect?      

Flowering plants have evolved one of the most complex and "sexiest" life cycles on earth. In fact, they have "double fertilization" involving two sperm rather than the usual one. In a mature seed, the embryo originates from a zygote formed by the fusion of sperm #1 with an egg inside the embryo sac. Sperm #2 fuses with the two polar nuclei forming the nutrient-rich endosperm tissue. When you consume coconut meat, coconut milk or popcorn you are eating endosperm. In the case of popcorn, the endosperm has exploded due to the pressure build-up inside the grain. Botanists have devised all sorts of terms to explain plant sexuality including unisexual, bisexual, asexual, self-fertile, self-sterile and polygamous. At least 90% of all flowering plants have bisexual flowers containing male and female organs. Many of these species avoid inbreeding and incest by having their sex organs mature at different times. In protogyny the female organ is receptive before the male is mature, and in protandry the male is ready before the female is receptive. This cleaver strategy favors cross pollination between different individuals. Some plants have only unisexual flowers and are dioecious with separate male and female individuals in the population--like date palms, edible figs, willows, cottonwoods, marijuana and people. The term homosexual is probably not politically correct for plants, although many plants are unisexual with flowers of only one sex. Poison oak is essentially dioecious, but it may also be polygamous with bisexual and unisexual flowers on the same individual. Figs are especially interesting because they have tiny unisexual male and female flowers inside a fleshy structure called a syconium. A minute female wasp squeezes into the syconium to pollinate the flowers and lay her eggs. After a few months, the new generation of wasps have an orgy inside the syconium and fertile females exit and start the entire cycle over again.

Protect Your Anthers

Up until the late 19th century, sexuality in plants was vigorously denounced by staunch theologians who believed in the literal translation of the Bible. According to Genesis 1, plants were created on the 3rd day. Not until the 6th day were animals and people created, and the words "male and female." Without male and female there could be no sex, therefore plants did not have sex. Flowers were erroneously considered sexless things of beauty. This preposterous assumption is undoubtedly the origin of the unfortunate term "deflowered" for a woman who has lost her virginity. Chauvinistic botanical ignorance has been perpetuated for centuries, including ridiculous ideas that the male contributes the seed. Not only does the female contribute the seed and egg, but also the vital extrachromosomal genes in cytoplasmic organelles called mitochondria and proplastids. The latter organelles become chloroplasts--the photosynthetic life blood of plants. Have you thanked your mother lately for your mitochondria?

A full-blown case of anther smut (Ustilago violacea) on the wildflower Silene verecunda ssp. platyota on Palomar Mountain in San Diego County, California, USA. The fungal disease on this native wildflower is definitely in the advanced stages.

At this time of sexual hysteria it is reassuring to know that plants also have sexually transmitted diseases. One of the most serious is anther smut (Ustilago violacea), the dreaded venereal disease of the plant world. Anther smut belongs to the Class Basidiomycetes in the fungal Division Eumycota. This debilitating fungal disease causes the male organs (anthers) to blacken and shrivel, resulting in sterility and a very unsightly floral appearance. Anther smut is spread by unsanitary, promiscuous insect pollinators who carry the infectious spores from one plant to another. The spores infect healthy individuals during the spring flowering season, erupting in their sex organs a year later when the plants once again enter their mating cycle. Floral castration is a rather drastic measure and infected individuals are seldom taken to a smut clinic, so diseased plants just keep on reinfecting the population. Safe sex is effective, but slipping miniature condoms over the anthers is tedious and much too impractical. Wise plants avoid the risk of sexually transmitted diseases by developing an asexual life style. They simply clone themselves vegetatively. Some can even produce apomictic seeds without sex. The embryo develops parthenogenetically from an unfertilized egg or from other cells in or surrounding the embryo sac.

Silene verecunda ssp. platyota on Mt. San Jacinto with a full-blown case of anther smut (Ustilago violacea). This sexually transmitted disease is spread by insects.

There are many additional species of smut fungi in the order Ustilaginales, particularly smuts that attack grasses. Some of these include corn smut, oat smut and wheat smut. There are even smuts that attack weedy grasses such as Johnson grass and Bermuda grass. These fungi typically infect the fruiting inflorescence region with sooty masses of spores.

Bermuda grass inflorescence (Cynodon dactylon) infected with Bermuda smut.

See Ergot Fungus That Attacks Rye Grass

  • Thrall, P.H., Biere, A. and J. Antonovics. 1993. "Plant Life-History and Disease Susceptibility: The Occurrence of Ustilago violacea On Different Species Within the Caryophyllaceae." Journal of Ecology 81: 900-909.

X-Rated Sexuality In Minute Protogynous Wolffia Plants
Images taken with Sony W-300 through Bausch & Lomb dissecting microscope.

Close-up view of Wolffia sample from a lake in Minnesota: Wolffia borealis (1) and W. columbiana (2). The average length of each Wolffia plant body is 1.0 mm (1/25th of an inch). Magnification 15x.

Flowering Wolffia columbiana: On individual plants, maturation of minute flowers within the dorsal floral cavity is protogynous: The stigma is receptive before the anther releases pollen. When the stima is receptive a droplet of stigmatic fluid is secreted. By the time the anther has split open and released its pollen, the stgma has already dried and withered. This strategy favors cross pollination between different plants. Magnification 20x.

Protogynous Wolffia columbiana: The stigma has already dried and withered. The anther has not yet released its pollen grains. Magnification 40x.

Floral "orgasm" of Wolffia columbiana: A mass of pollen grains have been released from a dehiscent anther within the floral cavity. The stigma has already shriveled up and is no longer receptive. Magnification 25x.

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