Wednesday, April 01, 2009

Invasive species: wavyleaf basketgrass - Oplismenus hirtellus subsp. undulatifolius

An invasive species is spreading from the Baltimore area of Maryland south to Washington and west to the Blue Ridge of Virginia. Like a fire in the forest, wavyleaf basketgrass (Oplismenus hirtellus subsp. undulatifolius (Ard.) U. Scholz, Phanerog. Monogr.) [1] is spreading rapidly and replacing the natural diversity with its mono-culture habit of eco-system and eco-service destruction. This grass, which remains taxonomically confused and, therefore, not precisely identified or categorized, is spreading in public parks and on private lands in the Baltimore Washington Metropolitan area. picture from
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Some species within the genus are sold in a highly unstable variegated form in the nursery, reportedly under a number of names, including Pancum spp. This species is not yet identified as the species loose in the public lands. Maryland Department of Natural resources reports that ”The native grasses are basketgrass (Oplismenus hirtellus) and its related native subspecies bristle basketgrass (Oplismenus hirtellus ssp. setarius). The exotic subspecies is wavyleaf basketgrass (Oplismenus hirtellus ssp. undulatifolius), and up to the summer of 2008, Maryland was the only place on the North American continent that this grass had been reported.”
There is an ongoing effort of some stakeholders to eradicate this species while before it becomes another overwhelming challenge to our natural systems and gardens Japanese stiltgrass (Microstegium vimineum (Trin.) Camus). In November, 2006, I posted an essay about Oplismenus hirtellus subsp undulatifolius, and have been following its progress ever since: v. Sunday, 2007: Invasive Species follow up: Basket Grass Removal in Beltsville

At a high philosophical level, the stakeholders interested in this newly detected invasive species are divided by the precautionary principle on the one hand and the proactionary principle on the other. The precautionary stakeholders want action now because they believe that there “… is a moral and political principle which states that if an action or policy might cause severe or irreversible harm to the public or to the environment, in the absence of a scientific consensus that harm would not ensue, the burden of proof falls on those who would advocate taking the action.” The proactionary parties are guided by their belief system are opposed to early action “… when restrictive measures are proposed: Assess risks and opportunities according to available science, not popular perception.”

Effectively what this means is that one side wants to go “public” and ask gardeners and horticulture in general to voluntarily stop selling and planting whatever species they are selling until the correct taxonomy is established the confusion: The other side is unwilling to shout fire in a crowded theater, and wants to wait because the prima facie evidence is that the plant species in the trade - no matter how aggressive - is different from the one running loose in the mid Atlantic woodlands. And effectively, a chance for early detection and rapid response is fading. Sic transit mundi

[1] Peterson, Paul M.. Department of Botany, MRC-166, United States National Herbarium
National Museum of Natural History, Smithsonian Institution Washington, DC 20013-7012, 202-633-0975, Fax 202-786-2563; :

The taxon [Oplismenus hirtellus subsp. undulatifolius (Ard.) U. Scholz, Phanerog. Monogr. 13:147. 1981. Panicum undulatifolium Ard., Animad. Spec. Alt. 14, pl. 4. 1764. Oplismenus undulatifolius (Ard.) P. Beauv., Ess. Agrostogr. 54, 168, 171. 1812, nom. nud. Oplismenus undulatifolius (Ard.) Roem. & Schult., Syst. Veg. (ed. 15) 2: 482. 1817. Orthopogon undulatifolius (Ard.) Spreng., Syst. Veg. 1: 306. 1824 (1825). Type: ITALY. cultivated, Arduino s.n. (holotype: M; isotype: C).] as treated by Scholz (1981) and all others is temperate in distribution, and is said to be found in “damp shady places” by Clayton (1980); ranges from Spain, northern Italy, former Yugoslavia through the Caucases to southeast Asia (Scholz, Pp. 147−155). In Tsevlev (1983) it says the taxon is found “in deciduous forests, among shrubs, forest glades, gardens and parks; up to lower mountain belt….Mediterranean, Asia Minor, Iran, Himalayas, Japan, China (southern part).”

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