Clones among us

THE NATURAL VIEWPOINT

Clones are in the news again, especially artificial cloning of

human beings. I stress the word “artificial” because nature has been

cloning plants and animals for a very long time without test tubes.

I’ll start with plants.

Plants that reproduce vegetatively, without making flowers and

seeds, produce identical copies of themselves. Violets, strawberries,

mint, and bamboo, among others, send runners (horizontal stems) out

from the main plant. Where they root they produce another plant -- an

identical copy, or clone. One of the oldest plants still around,

Equisetum, or horsetail, is notorious for spreading out and taking

over a garden if not contained. Fossilized Equisetum can be found in

coal beds hundreds of million of years old, so this strategy is

ancient indeed.

Cloning is common in the plant world, and the basis for a lot of

garden planning. Ground covers wouldn’t be of much use if they didn’t

spread out from the original small plants to, well, cover the bare

ground.

A plant that can be divided at the base and the resulting smaller

plants grown is also reproducing asexually. This includes a number of

wild and garden plants like iris and artichoke. If the clump gets

bigger with time, it’s cloning itself. Unfortunately, giant reed

(Arundo), a serious pest plant in wetlands and stream beds,

reproduces easily this way, and also from stalk segments that break

off and wash downstream.

Any plant that roots from a fragment or cutting is cloning itself.

This includes African violets, grapes, and both of our native cactus,

prickly pear and cholla. Prickly pear pads break off from the main

plant, fall to the ground, and soon send out roots. A rooted pad

becomes a new plant.

In the leggy and extremely spiny cholla cactus, the stems break

naturally into segments a few inches long. Many hikers have had the

unfortunate experience of brushing up against a cholla, getting a

segment firmly (and painfully) attached. The desert species is

nicknamed the “jumping cholla” for the ease with which the stem

segments attach themselves to unwary hikers.

The most common plant around here that reproduces by cloning is

the eucalyptus. My professor at UC Irvine argued that the trees,

brought here more than 100 years ago from Australia, were not

“naturalized” to California because they weren’t seen to reproduce

sexually; instead, they sent out underground stems that rooted and

sprouted into new trees.

Cloning allows the trees to reproduce quickly and efficiently.

That’s how a few eucalyptus trees, planted along Laguna Canyon Road

in 1921 through the efforts of artist Anna Hills, became the

ever-expanding phalanx of shaggy monsters that invaded Lake No. 1.

The trees are now supporting the inbound right lane of the road.

But in tough conditions, seeds may be the best way to go. After

the 1993 fire, hundreds of tiny seedlings appeared out of the ashes

beneath gum trees in my neighborhood in Laguna Canyon. Something

about the fire stimulated the seeds to germinate, adding another,

more sexy, way for eucalyptus to continue their invasion of

California.

* ELISABETH BROWN is a biologist and the president of Laguna

Greenbelt Inc.