Biology Reference
In-Depth Information
to invade otherwise undisturbed habitat in remote and largely uninhabited areas
(Queensland Department of Primary Industries and Fisheries 2007b).
3.8.2 An Unequivocal Candidate for Eradication: Heracleum
mantegazzianum
Reluctance to embark on a plant eradication program can draw from a pool of
conventional wisdom: the target species is already too widespread across too many
sites, it is inconspicuous, it occurs in inaccessible habitats, the public is unlikely
to view the introduced plant as a widely shared hazard, and the eradication will be
prohibitively costly. The case for eradicating
H. mantegazzianum
(Giant hogweed)
in the US trumps all these reasons. This large perennial Umbellifer is native to the
subalpine zone in the western Caucasus Mountains (Azerbaijan, Georgia, and
southern Russia) (Mandenova 1951 and Otte and Franke 1998 as cited in Page
et al. 2006). It was likely introduced deliberately in the US as an ornamental and
as a spice in Iranian condiments (RNM, pers. obser.). Its introduction has been an
egregious mistake as most aerial plant parts are festooned with stiff pustulate-
based hollow trichomes that produce linear furanocoumarins. Humans and other
mammals are highly sensitive to the phytophotodermatitis that these compounds
produce, which are activated under UV. Contact with these trichomes produces
painful blisters and even scarring (Page et al. 2006 and references therein). Any
culinary/ornamental benefits of this plant are more than outweighed by its serious
health risk.
Fortunately, Giant hogweed has been recognized as a Federal Noxious Weed in
the US since the mid-1980s, and consequently its interstate transport is forbidden
(Foy et al. 1983); 12 states further forbid its intrastate movement or even its occur-
rence (http://plants.usda.gov/java/noxiousDriver). Even though it now occurs in 16
US states, its total area of residence is probably < 100ha (M.A. Bravo, pers.
comm.) - seemingly well within the scope of even a modestly-funded eradication
project. The ability to eradicate Giant hogweed is aided by the plant's ecological
amplitude: it does not become established in communities with high plant cover.
Instead it occupies disturbed sites (e.g., roadside ditches, old fields, gravel bars) as
well as riparian areas (Page et al. 2006). And certainly destruction of Giant hog-
weed would seem well worth the cost - a case where a cost-benefit analysis seems
needless, given the legitimate concern for public health.
In the US, Giant hogweed may be most widespread in Pacific Northwest, far
removed from other populations in the Mid-West and along the East Coast. The western
third of Washington, centering on metropolitan Seattle, has reportedly > 1,000 loca-
tions. Many of these locations likely support a single plant, but more extensive popula-
tions have become established along stream courses by water-borne seeds (King
County DNRP/WLR 2006). These streamside populations warrant immediate attention
because
H. mantegazzianum
spread initially in the Czech Republic along river courses
(Pysek 1991). The legal requirement to destroy Giant hogweed coupled with its serious
