Monday, January 23, 2012

Week of the Clones: the ethics of vegetative reproduction

Is cloning ethical? That question is something of a hot-button issue in bioethics, especially as we get better at it. Forty years ago, we couldn't so much as clone a fruit fly; today, we can manage sheep and dogs, and biologists are ever honing our techniques. Soon, we may be able to clone human beings.

Oh, and did I mention that plants beat us to the punch by several hundred million years?

"Reproductive cloning", in the most precise sense, just means any form of reproduction where the offspring is genetically identical to the parent. In the most popularly familiar sense, this means the cloning of complex animals like, say, a sheep -- a process requiring a great deal of careful lab work. More broadly, though, it actually refers to any kind of asexual reproduction. Virtually all bacterial reproduction is clonal: when a cell divides, it is cloning itself. A great many animals reproduce asexually, too: when a planarian gets split in two and each end grows back into a complete individual, it is cloning itself.

Plants clone themselves all the time, both on their own and with human assistance. Most serious gardeners will, at some point, have propagated a favorite plant from cuttings or by dividing a clumping perennial: the resulting plants are clones of the original. When a tree produces root suckers, it is cloning itself. When a bulb (say, of an Asiatic lily or a garlic plant) produces smaller bulbs off its sides, it is cloning itself. Cloning is absolutely rampant in the plant world. It's called vegetative reproduction, and it's about as unusual as a rabbit having a litter of kits.

That said, the fact that plants clone themselves regularly doesn't make their methods of doing so any less interesting. The types of vegetative reproduction are as varied as plants themselves. This week, I'll be posting entries on vegetative reproduction both natural and artificial, in plants as diverse as mosses, bananas, grapes, and mother-of-thousands. Look for more coming up in the Week of the Clones!


  1. Mother of thousands? I haven't heard of that, but it instantly put in mind a picture of the hens & chickens plant, which must be another example of vegetative propagation. :-)

    1. Mother-of-thousands, mother-of-millions, etc.; they're common names for Kalanchoe daigremontiana and a few similar species. You know the one -- I have a sizeable, very sprawling houseplant, and it drops its babies everywhere. More to come. :D

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