Above: The Tennessee coneflower (Echinacea tennesseensis).
Trade in rare plants sows trouble for endangered species.
Those planted outside their normal habitats can devastate native growth and can hybridize with other species, blurring their genetic lines, scientists warn.
Rare plants are increasingly finding their way outside their normal habitats because of commercial sellers and citizen conservationists, two ecologists warn. Unless the movement of such plants is better regulated, it could spell trouble for endangered species as well as the environments to which they are moved.
The caution, written by Patrick Shirey and Gary Lamberti at the University of Notre Dame and published in the journal Nature, warned that rare plants grown outside their native territories can disrupt their new environment, hybridize with related plants and blur their genetic individuality, or carry pathogens them that devastate other plants. They called for more uniform and rigorous regulation of Internet trade in rare plants across the U.S.
The study suggests that it is surprisingly easy to get your hands on an endangered plant. That's letting some activists engage in their own efforts to help save rare species from extinction. But some conservation experts worry that there are potential risks when private groups unilaterally decide to move their favorite plants to new habitats.
"There's been a lot of attention to the trade of endangered animals. There's been less attention to the trade of endangered plants," says Shirey.
The scientists noted that about 10% of the 753 plants federally listed as threatened or endangered are being advertised for sale online. They recently found more than 50 sellers were offering to ship these plants between states, which is illegal interstate commerce under federal law without a permit.
Other sellers were offering these plants for sale in-state, which is legal. However, once a person obtains a plant, it's easy to move it around, Shirey says. It's legal, for example, for someone to drive to a nursery in one state, purchase an endangered plant, and then drive it to another state.
"You could drive to South Carolina and bring a plant up to Maryland, and you would not be violating federal law," says Shirey.
What's more, people who own any endangered plants on their property can give them as gifts to anyone. That's because federal laws treat endangered plants very differently than endangered animals.
"It dates back to a very old tradition of how we treat species," says Shirey. "Under common law, the person that owned the land owned the plants that were on the land, whereas the king owned the animals under English law."
Above: The Melaleuca or Australian Paperbark Tree (Melaleuca quinquenervia).
Though increasing the numbers of rare plants may on the face of it seem helpful, ecological disasters can occur, Shirey said. He cited the case of the Australian paperbark tree (Melaleuca quinquenervia (Cav.) S.F. Blake or punktree, whose coastal habitats are threatened. That same tree, imported into the U.S. in the early 1900s, is considered a noxious weed in the United States and has caused millions of dollars of damage in the Florida Everglades.
Above: Cabbage on a stick (Brighamia insignis).
Shirey worries about Brighamia insignis, known commonly as alula, or cabbage on a stick. In its natural habitat in Hawaii, fewer than 10 individual plants remain because their natural pollinators appear to have gone extinct. The plants can be hand pollinated and cultivated and are available at online nursery websites for less than $30 a pop.
Shirey also pointed to the case of Tennessee coneflower (Echinacea tennesseensis (Beadle) Small), which is currently listed as an endangered species (although the U.S. Fish and Wildlife Service has proposed it be delisted). The Tennessee coneflower hybridizes easily with other coneflower species, and in 2003 a commercial grower introduced a cross to the market. Having a hybrid available to purchase could reduce the threat of poaching. But, Shirey said, if these hybrids entered the native habitat they could compete for resources and hybridize in turn with the Tennessee coneflower.
Shirey noted that there is already a population of hybrid coneflowers growing near the home of the Tennessee coneflower.
Other groups are planting rare plants far from home with altruism in mind, not profit. Shirey cited as an example the Torreya Guardians, a loose-knit group of citizen and professional conservationists who are replanting the Florida torreya (also known as the Florida nutmeg or Torreya taxifolia Arn.) , a type of evergreen tree, on private land outside its current natural habitat. The conservationists justify this action by pointing out that the torreya used to thrive farther north in the last warm period between glacial freezes. Read more about the Florida Nutmeg below.
"It's not in its correct habitat right now. It should be in the Appalachians," said group cofounder Connie Barlow.
"I felt I was the only advocate," says Barlow. "I was the only one who was going to say it's not sufficient to just spend hundreds of thousands of dollars trying to find a way to make this plant be able to live again in the Panhandle of Florida. I said, 'I can do it for zero money, working with fellow volunteers, and we can legally give this plant a chance.' "
Her view is that the tree probably lived northward during the previous warm times of the past 2.5 million years, and her group is simply returning it to an older range.
Citizen actions that involve moving around endangered plants into new habitats worry Mark Schwartz, a plant ecologist at the University of California, Davis.
"It takes a lot of thought and probably some science to understand the risks there," he says. "And volunteers generally aren't going through that assessment process. They're going out and doing things."
Still, Schwartz understands why they want to do something. He says far more money is spent on helping cute and fuzzy endangered animals than plants.
"The Endangered Species Act is rather anemic with respect to accomplishing the job of protecting plants," he says. "It encourages people to take this job onto their own shoulders, so there's a tension there."
Schwartz says private citizens can help native plants, by pulling weeds or conserving their land. But when it comes to resettling a plant in a new area, he urges caution and says conservation groups need to come up with guidelines to help keep plant lovers from inadvertently making big mistakes.
Citizen conservationists certainly have a part to play in saving rare plants, Shirey and Lamberti said. However, they added, a better approach would be to let federal officials take the lead and coordinate with citizen advocacy groups eager to help.
"Of all the possible impacts of exotic species on the native species and communities, I think the possibility of bringing in a pathogen or pest is probably the greatest," said biologist Dan Simberloff, cofounder of the Institute for Biological Invasions biologist at the University of Tennessee, Knoxville, who was not involved in the study.
Above: Florida nutmeg, Torreya taxifolia.
Florida Nutmeg (Torreya taxifolia Arn.) is an endangered species. This small rare tree is nearly extinct in the wild, threatened by a fungal disease of the stem. Known locally as stinking-cedar because of the pungent odor given off when the leaves are crushed, it was first discovered in 1833 by H. B. Croom near the Aspalaga Crossing on the Apalachicola River. Its rarity limited its use except locally for fenceposts and Christmas trees. The largest living specimen is in North Carolina and measures about 89 cm (35 in) in d.b.h., 14 m (45 ft) in height, with a crown spread of 12 m (40 ft).
Its Native range is in three counties in Florida, Gadsden, Liberty, and Jackson. Fewer than a thousand specimen grow wild along a stretch of the Apalachicola River. It is also found in southern Decatur County, GA, just north of Chattahoochee, FL. The natural range of this species extends along the limestone bluffs for a 64-km (40-mi) stretch on the eastern bank of the Apalachicola River and its tributaries from Chattahoochee south to Torreya State Park in northern Liberty County, FL. One population exists approximately 11 km (7 mi) west of the Apalachicola River in the vicinity of Ocheessee Pond in Jackson County, FL.
The tree can perpetuate itself vegetatively by producing sprouts at the base of the parent tree, although, in almost every instance, only one sprout survives after several years. Probably every existing Florida torreya in its present native habitat is a product of vegetative reproduction.
Genetics: No population differences have been observed in this species. No natural hybrids occur because this species is separated from its nearest North American relative, T. californica, by more than 2090 km (1,300 mi).
If Florida torreya is to be preserved, it will be necessary to isolate and propagate blight-resistant trees. Such genetic material may be propagated from Torreya taxifolia cuttings because they root readily. Once the seedlings are well established, they may be outplanted in suitable habitats along the Apalachicola River.
Above: A juvenile Torreya taxifolia, also known as the stinking cedar or Florida nutmeg.