PRICKLY PEARS AND MARTIAN WEEDS - Rethinking Invasion Ecologies from the Environmental Humanities - page 143

fecundity. Its seeds were simply poured down into the water of the Wey and
Thames, and its swiftly growing and Titanic water fronds speedily choked
both those rivers.
(Wells, [1898] 2009: 170)
What has just happened? Suddenly this land-dwelling plant with cactus-like
branches has become aquatic and possesses Titanic water fronds.
Upon first encountering this difficulty, I tried to reconcile these details with the
facts of the prickly pear's dispersal. MacOwan's memorandum records the growth
of the prickly pear in '[t]he courses of streams, and flats between their curvatures'
(MacOwan, 1888: 166). It also notes the spread of the plant to new regions by way
of flooding rivers and landowners' practice of disposing of uprooted plants by
throwing them into waterways, scenarios that could be read as models for the spread
of the Martian red weed by water. However, even if one entertains the possibility
of a water-dwelling cactus, how does one account for the red weed's Titanic water
fronds, which impede the narrator's feet as he attempts to wade through the shallow
floods and which turn the river into 'a bubbly mass of red weed' (Wells, [1898]
2009: 171, 186)?
It is at this point that it becomes clear that no single historical example can
wholly account for the Martian red weed, but this does not mean that historical
models cease to be relevant. Following the example of Matthew Chew, I turned
to the Canadian waterweed, Elodea canadensis , as an additional model for Wells's
Martian red weed. The Canadian waterweed is a perennial aquatic herb native to
North America that grows submerged in marshes, lakes, and streams and has a
tendency to form large masses, which it did with considerable frequency following
its accidental introduction to Britain in the early nineteenth century. Once
introduced to Britain, it spread rapidly, choking waterways, before declining just
as rapidly for no clearly discernible reason in the late nineteenth century. In an
article in the 27 June 1872 issue of Nature , A. W. B. remarks on 'the suddenness
with which the Canadian waterweed, Elodea canadensis , filled up all our canals and
water-courses within a few years of its first introduction' (A. W. B., 1872: 164).
In the 21 January 1886 issue of Nature , it is recorded that 'Mr Siddal writes on the
American waterweed ( Anacharis alsinastrum , Bab.) [a synonym for Elodea canadensis ],
its structure and habit, and adds some notes on its introduction into this country,
the causes affecting its rapid spread at first, and present apparent diminution' (Anon,
1886: 279). By the late 1880s, the waterweed had already spread to its greatest
extent and was recognised to be in retreat.
The Canadian waterweed thus provides a model for the Martian red weed's
congestion of the Thames, which, as Wells's narrator recounts, caused the water
of the river to pour 'in a broad and shallow stream across the meadows of Hampton
and Twickenham', so that these suburbs were covered in 'sheets of the flooded
river, red tinged with the weed' (Wells, [1898] 2009: 172). The red weed's
subsequent fate also recalls the history of the waterweed in Britain. Wells's narrator
reports that 'in the end the red weed succumbed almost as quickly as it had spread',