The Original Mystery Plant
Dr. John Nelson

Photo by Linda Lee

What's the difference, botanically, between a reed and a cane? I'm not sure I know. Both of these are very old words that tend to refer to hollow-stemmed, grass-like plants. Here is a plant that seems to fit, and is, as well, a true member of the grass family.

It is native to southern Europe and probably also parts of the Middle East where it grows naturally in damp places especially along marshy coasts. It is now a common plant through most of the southern half of the United States from coast to coast after having been brought to our shores and intentionally planted. It can be seen not only on coastal spoil-banks, low roadsides and ditches but also well inland.

It sometimes forms impressive patches or even deep, dense thickets. The plants bear extremely vigorous, slender rhizomes below the soil, and it is by these that the clumps spread. The plants are capable of forming tall bamboo-like stems, sometimes as high as 12 feet or more, and these often lean over.

The leaves are long and pointed and smooth on both surfaces. The leaf bases (sheaths) wrap around the stem and closely overlap each other. The blades of the leaves, scratchy on the margins, tend to spread horizontally forming two ranks up and down the stem. Some forms of this plant have prominently variegated foliage, exhibiting green and white longitudinal stripes.

In the summer and fall, large, branched panicles appear at the ends of the stalks. Each panicle will consist of many hundreds of tiny flowers, and as is the case with all grasses, the flowers themselves are tiny and chaffy.

Collectively, the flowers lend a dramatic feather-duster effect to the stem. The flowers don't generally make grains, and so the plants tend to be spread either accidentally or intentionally by the divided rhizomes. A big patch of these plants in bloom can be very dramatic, and for this reason landscapers have sometimes used it as an accent plant.

People have been growing this species for thousands of years and not just because it's pretty. The stripped stems can be used for building lattices, and the dried leaves for stuffing things and for thatch. Large patches, grown in rows, have been used as windbreaks, and hedges can be made by constantly clipping back the stems.

This plant holds considerable promise as an alternative fuel and has already been investigated as a combustible source of energy for power plants. Woodwind players might know this plant as a prime source of instrument reeds, which are derived from the pithy interior of the stem. The hollow stems have been used for flutes.

There's a dark side, though. This species, like so many others now present outside their natural range, is an aggressive weed and a quick colonizer; it's a serious pest in California and Hawaii. Natural areas, especially in coastal habitats and along rivers, are susceptible to its nearly uncontrollable spread. Home landscapers are advised NOT to grow this plant!

Answer to this week's mystery plant

Giant reed, Arundo donax

Dr. John Nelson is the curator of the USC Herbarium.

To learn more about the Herbarium, call 777-8196. The

department also offers free plant identification.

www.herbarium.org