Invasive Species Sheet - Japanese Stilt Grass
Invasive Species Identification Sheet
Japanese Silt Grass (Polygonum cuspidatum
Sieb. & Zucc.)
Alternate Common Names: Vietnamese Stilt Grass; Asian Stilt Grass; Nepalese
Browntop; Chinese Packing Grass; Annual Jewgrass; Basketgrass; Mary’s Grass
Alternate Latin Names: Andropogon vimineus
Trin.; Microstegium imberbis Nees
ex Steud.; M.
willdenovianum Nees ex Lindl.;
Eulalia viminea (Trin.) Kuntze;
Pollinia viminea (Trin.) Merr.;
P. imberbis Nees
ex Steud.; P. willdenoviana (Nees
ex Lindl.) Benth.
- annual grass; shade tolerant; lush, dense, light green stands are prominent in
- sprawling growth; frequently with nodes marked by stiff, root-like structures
dropping into the ground and leafy stems growing upward
as tall as 3'; easy to pull up
- leaves alternate, 1 1/4"–3" long, up to 3/8" wide, not thick; with pointed tip
and tapered base
- leaf midvein area frequently is wide and shiny white (best seen in sunlight)
- flowers mid-Sept. on stalks attached at ends of leaf stems; seeds late-Sept.
or early Oct.
Japanese Stilt Grass is generally recognizable by vegetative characteristics.
It is often confused with (and may grow
intermixed with) the native White Grass (Leersia
virginica Willd.). Important characteristics to check for on
Japanese Stilt Grass vs. White Grass are: (1) stem nodes hairless (check with
hand lens) vs. tiny hairs protrude
from nodes (usually visible even without a hand lens), (2) all thin roots vs.
some roots are short, thickened
rhizomes (underground stems), (3) flower clusters on 1 or 2 (up to 5)
densely-packed, spike-like branches each
with many pairs of green spikelets vs. flowers in an open panicle usually with
5+ branches, (4) late fall leaf color is
wine red/purple and pale yellow vs. pale green or tan.
In New England, Japanese Stilt Grass seeds sprout in June. Plants grow
rapidly on shady, moist sites where the soil
has been disturbed, for example, riparian areas scoured by high water,
roadsides, and lawns.