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Commelina benghalensis (COMMELINACEAE) Tropical Spiderwort, Hairy Wandering Jew

Image: Habit

Photo: Robert Whyte

Annual or sometimes perennial herb, known as Benghal Dayflower, Tropical Spiderwort, Wandering Jew

Stems have a high moisture content, and once well rooted the plant can survive for long periods without moisture availability and can then grow rapidly on the onset of rains.

An aggressive weed that produces aerial (above ground) and subterranean (below ground) flowers. This results in viable seed being produced both above and below ground. Will also root at the nodes and can be propagated from cut stems. Light cultivation can often break plant parts and increase the area of infestation.

Tolerance to glyphosate has been documented.

COMMELINACEAE named for two 17th century Dutch brothers, both botanists

Image: Brown hairs, hairy fused spathe

Commelina benghalensis
Photo: Robert Whyte (note brown tipped hairs and fused hairy spathe )

Confusion can occur with a number of other weedy Commelina species, but the following combination of characters may be used to distinguish C. benghalensis: all three petals blue, leaves broadly elliptical (length up to twice width only), spathe sealed to form triangular pocket, seeds rugose, presence of stolons, leaf sheaths with reddish-brown-tipped hairs. C. diffusa, the commonest of other species, has blue petals, but the spathe open along one edge, leaves are narrower, seeds are smooth, and there are no stolons. C. forskalaei has stolons and rough seeds, and the spathe is sealed, but the leaves are narrower, and their length is up to 4 times the width, and wavy-edged (Holm et al 1977, Drummond 1984). None of the other weedy species have brown-tipped hairs. Hence this is an especially useful character when looking at vegetative material.

SOURCE: North American Plant Protection Organization (NAPPO)