SOME PLANTS HAVE ODD TRAITS

by Whit Gibbons

May 20, 2007



If plants gave out honors among themselves, one awards category might be "strangers in a strange land: surviving against the odds." Among the prime candidates for such an honor would be ginkgoes, Franklinia, and tumbleweed.

The "tumbling tumbleweed" looked good in old Hollywood Westerns as a round, basket-like object rolling across the trail in front of a posse or a cowpoke on a dark and windy day. Tumbleweed is part of the legends of the Old West. But tumbleweed qualifies as a glamour species only in the eyes of moviegoers from back east. The species was never popular with ranchers and farmers. The leaves are sharp, and people and horses alike can suffer painful cuts from the spines. In the modern-day West, tumbleweed-vehicle collisions can result in the need for a new paint job. The huge, dried balls of plants add to their nuisance value by piling up against houses, barns, and fences, creating a fire hazard if nothing else. The fire specter is dramatically increased by the prospect of a tumbling fireball leaving a trail of burning prairie grasses or crops.

Farmers in the Dakotas in the late 1800s were the first to recognize tumbleweed as a serious pest. None of them liked it one bit. Tumbleweed was so destructive to the American frontier that some farmers even hinted at conspiracy. As an identifiable social and religious group with different customs, Russian Mennonites were already a target for frontier discrimination. As tumbleweed problems increased, some farmers blamed the Mennonites. The religious group was accused of intentionally introducing the noxious weed to America in a vindictive plot to get even for the prejudices against them. The U.S. Secretary of Agriculture sent a botanist to the region to study the tumbleweed problem and seek control measures. He eventually demonstrated that the plant, known by botanists as Russian thistle and by some people as wind witch, was introduced by accident in a shipment of flax seeds from Europe, where the plant was not native either. The finding dismissed the claims against the Mennonites.

The community of the Great Plains first felt the brunt of the newly introduced agricultural pest as the rolling plants spread their seeds across the land, invading croplands, towns, and open prairie. Ironically, although a bane to developing farmlands, tumbleweed owes its success to agricultural practices. A tumbleweed plant disperses its seeds by rolling across the landscape. The clearing of forests and the elimination of tall prairie grasses aided such a lifestyle; the dense natural habitats would not have allowed suitable dispersal or seedling establishment. The worldwide prosperity of Russian thistle can be attributed to an agricultural society that set up ideal conditions for its survival.

Tumbleweed is a botanical success story in barren habitats throughout much of the world, including Eurasia, Australia, and North America. According to some accounts, despite its abundance in some areas of the world, tumbleweed is apparently extinct in its original native habitat in Russia.

Franklinia, a member of the tea family, is a small evergreen tree originally described in the 1700s by William Bartram. The early explorer discovered a grove of two to three acres in the bottomland forests along the Altamaha River in Georgia. Neither the grove nor a single tree has ever been rediscovered. The only survivors of the entire species, available from horticultural companies, are descendants from seeds Bartram collected and sent to England.

Ginkgo trees are also extinct in the wild and no one knows for sure where they came from. Only one species exists, with a botanical history that traces it back to temple gardens of China. The ginkgo has one of the longest fossil records among the higher plants, has no wild representatives, and yet prospers today in the Orient and North America. Most are within planting distance of a house or building.

Franklinia, ginkgoes, and tumbleweed are botanical paradoxes. In contrast to the many species threatened today by encounters with humans, all these species owe their existence in America, and perhaps anywhere, to a consequence of the intermix of their natural history and a timely involvement by humans.

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