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Elisabeth C. Miller Library

Keyword: Plant reproduction

On sex difference among eggplant fruits

I read on a cooking blog that it’s important to be able to distinguish between male and female eggplants, because males are less seedy and therefore less bitter. Supposedly, the difference can be detected by looking at the indentation at the bottom of the vegetable. Females have long, deep, dash-shaped dents, and males have round, shallow ones. This is the first time I’ve ever heard of such a thing, and I’m wondering if you can confirm it.

There is no sex difference among eggplant fruits. The confusion may have come from the fact that eggplant flowers have male and female parts. Mary Keith, a nutrition educator with University of Florida Extension says:

“Please, don’t waste any sleep over trying to remember which one is which.
There are not ‘male’ or ‘female’ eggplants. They all come from the female organs of the
flower, but eggplant flowers have both male and female organs. The seeds they
contain will grow into plants that make flowers with both male and female parts.[…] The shape of the scar where the flower fell off doesn’t tell you whether the fruit is a boy or a girl.”

Keith goes on to explain the best way to select an eggplant for cooking purposes:

“The best place to start is what you can see, the skin. There should be a little bit
of the stem still attached to one end. A ripe eggplant will have a smooth, bright, shiny
skin. It should be firm, not hard but not soft and soggy either. Whether it is purple, green, white or striped, if the skin is dull the fruit has been picked for too long. When you press on the skin it should spring right back at you. If it’s too hard to press in, then the fruit is too green and underripe. If it goes in and stays in, the fruit is too old. The texture is getting soft and it is more likely to be bitter. In general the smaller ones are usually better. Probably the best way to decide which ones to buy is to weigh them. […] The heavier one will be the better one. Some people say they can tell by knocking on an eggplant as they do a watermelon. In this case though, you do not want to buy one that sounds hollow. These will be dry and punky inside.”

Similar information comes from University of Illinois Extension:

“There is long-standing controversy about male and female eggplants, which is an inaccurate approach considering the fact that fruits are the product of sex and do not have it. However, it is folk wisdom worth some attention. Eggplants have a dimple at the blossom end. The dimple can be very round or oval in shape. The round ones seem to have more seeds and tend to be less meaty, so select the oval dimpled eggplant.”

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on monoecious plants and bisexual flowers

My neighbor says his Deodar cedar tree is bisexual, and it’s the male cones that are making so much pollen this October. He seemed to be saying this was unusual, and that not all cedar trees were like this, with both male and female cones. What’s the story?

Cedrus deodara is monoecious, which means that an individual tree will bear separate and unisexual male and female flowers. If the tree had bisexual flowers, each flower would be ‘complete’ and ‘perfect,’ that is, with male stamens and female pistil in each flower. So it’s clearer to call the tree monoecious than to say it is bisexual. According to Wayne’s Word: An Online Textbook of Natural History, “about 90 percent of all flowering plants have bisexual flowers with both male (stamen) and female (pistil) sex organs. The remaining 10 percent have unisexual male and female flowers on the same plant (monoecious species) or male and female flowers on separate plants (dioecious species).”

Most conifers (like true cedar) are monoecious. The male pollen cones are 2 to 3 inches long by October, and are found in great number on the lower parts of the tree. Female flowers are tiny, and usually found high up in the tree. Female seed cones take two years to mature. You might wonder how pollination can take place if the female flowers are up high and the pollen is down low.  Conifer pollen is wind-dispersed, so it might seem arduous for it to reach the female flowers up above. However, if you consider the geographic origins of the true cedars, you will notice that Deodar cedar is also called Himalayan cedar and like the cedar of Lebanon (C. libani) and the Atlas cedar (C. atlantica), its native range is mountainous. Imagine cedars growing on a sloping mountainside, and you can easily picture the pollen drifting downward to female flowers on the trees below.