Witches can cause their own horrors in horticulture

Angela O'Callaghan

Thursday, Oct. 9, 2008 | midnight

Over the past several years, Halloween has morphed from a single day when children could race home from school and change into some kind of fantasy or monster in order to collect candy and cash from "unsuspecting" neighbors. What we have now is something more along the lines of a "Halloween season." Trees are festooned with dangling jack-o-lanterns and front yards display spooky gravesites dripping with cobwebs. Doors and windows display ghosts and skeletons, and of course, witches.

Witches are reputed to be scary individuals who try to do frightening things to children in fairy tales.

In horticulture, witches can be no less terrifying. Many, but not all, of the plants that have "witch" in their names are indeed villainous.

First, let me mention the "good witches." Witch hazel (Hamamelis) is a yellow-flowered shrub that is used to produce a refreshing astringent. Unfortunately, it does not grow well in alkaline, salty, dry soils, so it is not a great choice for Nevada landscapes. An orchid found in North Carolina (Ponthieva racemosa) is known as "shadow witch," but again, it is not ideal for our challenging climate. There is a floribunda rose called "Witching Hour" that might be worth trying.

Aside from these, and perhaps a few other "good witches," quite a few plants containing the word "witch" in the name are unwelcome, and many of them will indeed survive in the desert Southwest.

Some witch plants are grasses. Two members of the genus Panicum are "witch grass" ( P. capillare) and "western witch grass" (P. dichotomiflorum). Even the noxious weed we commonly call "quack grass" or "couch grass" (Agropyron repens) is sometimes known as witch grass. Here is another good reason not to use common names if we have a choice; using proper names can lessen confusion.

Hylotelephium telephium can be called "witch's moneybags." This attractive plant probably grows in this region, but it is an invasive weed species listed by the USDA.

In parts of the world, including the eastern United States, a genus of root parasites known as "witchweed" (Striga) grows. This plant devastates the plants it encounters by sucking out its nutrients. Parasitic plants can be attractive, as this one is, but that makes them perhaps even more terrible.

The Mojave's difficult climate does not prevent the parasite dodder (Cuscuta) from wreaking havoc. Anyone who has seen something that looks like a tangled mass of orange or yellow string sitting atop wild plants has seen dodder. Some people know this freeloader as "witch's hair."

Finally, there is something known as "witch's broom." This is not a plant, but actually a phenomenon. When certain parasitic plants (or other organisms) land on a limb, it can cause the plant to respond by wildly producing masses of twigs and foliage. The resulting cluster can look like the business end of an old broom. It is very common on evergreens in this region.

There are indeed many witches out there. Enjoy Halloween, but do not bring these witch plants into the garden.

Angela O'Callaghan is the area specialist in social horticulture for the University of Nevada Cooperative Extension. She can be reached c/o the Home News, 2360 Corporate Circle, Third Floor, Henderson, NV 89074, or TheNews@hbcpub.com.