This perennial rush is 6-20" tall, consisting of a tuft of erect to
ascending basal leaf blades and more or less erect flowering culms. The
medium green, glabrous, and terete. The basal sheaths of the leaves
clasp the culms at their bases. These sheaths are mostly medium green
and glabrous while they are immature, although their upper margins are
white-membranous. The auricles (uppermost margins) of these sheaths are
white-membranous, soft, and rounded, sometimes becoming fragmented with
age. Eventually, the sheaths and their margins turn brown as they age.
The blades of basal leaves are 3-6" long and 0.5-1 mm. across; they are
medium green, flat, and glabrous. Both the blades and culms are rather
stiff. Each culm terminates in an inflorescence up to 4" long and 3"
across; usually this inflorescence is taller than it is across. The
inflorescence consists of a few primary branches that occasionally
divide into secondary branches; along the upper lengths of these
branches are several erect flowers that are sessile or nearly so. The
primary branches are erect to ascending and often slightly recurved;
the shorter secondary branches tend to diverge from their primary
branches to a greater or lesser extent. Both the primary and secondary
branches of the inflorescence are medium green, glabrous, and
Individual flowers are 3-4.5 mm. long and about
one-half as much across; their tepals and ovaries are about the same
length. Each flower has 6 tepals, 6 stamens, and an ovary with a single
style. The tepals are lanceolate in shape with membranous margins;
immature tepals are green, but they later become light brown. The ovary
of each flower is ovoid to ovoid-oblongoid in shape; the immature ovary
is green, but it later becomes light brown. Both the tepals and
ovary are glabrous. At the base of each flower, there is a pair of
short linear bractlets. At the base of entire inflorescence, there are
about 3 leafy bracts of variable size; these bracts are linear in shape
and ascending. The blooming period occurs from early summer
into the autumn; individual flowers remain in bloom for only a short
time and they are cross-pollinated by the wind. Afterwards, the flowers
are replaced by seed capsules that are the same size as the ovaries,
except they may be slightly more elongated and oblongoid in shape.
Eventually, these capsules divide into 3 parts to release their tiny
seeds. The seeds are up to 0.5 mm. long and brown; they are easily
blown about by the wind. The root system is fibrous.
The preference is full sun to light shade, wet to mesic conditions, and
poorly drained soil containing some clay or rocky material. This rush
can spread aggressively in some areas and it is difficult to pull out
by the roots.
Inland Rush is common
throughout Illinois, where it is native (see Distribution
widely distributed in eastern North America. Habitats include moist
prairies, prairie swales, seeps, depressions in rocky glades, soggy
meadows, paths in open woodlands, ditches along roadsides and
railroads, overgrazed pastures, grassy areas in parks, and poorly
maintained lawns. Inland Rush prefers areas with a history of
disturbance. It has low fidelity to any particular habitat.
Insects that feed on the similar Path Rush (Juncus
) probably also feed on Inland Rush. Examples of
include the Short-winged Meadow Katydid (Conocephalus brevipennis
which feeds on the seed capsules, and the Juncus Mealybug (Dysmicoccus
), which feeds on the roots. Other insects that may
these rushes include aphids (Prociphilus
e), the larvae of some Agromyzid flies (Cerodontha spp.
larvae of the Javelin Moth (Bactra
); see Gangwere (1961),
Blackman & Eastop (2013), Spencer & Steyskal (1986),
(1987), and others. Among vertebrate animals, the seedheads are
probably eaten by ducks and other waterfowl, while the foliage of
Inland Rush is usually avoided by cattle, Canada Geese, and other
herbivores because of its high silicon content (Lanning, 1972; personal
observations). The tiny seeds of this rush can probably cling to the
muddy feet and feathers of waterfowl, as well as the fur of mammals,
especially when they are wet. In addition, people probably spread the
seeds by means of their muddy shoes, mowing activities, and the wind of
passing motor vehicles.
A grassy lawn at Crystal
Lake Park in Urbana, Illinois. While Canada Geese are avid consumers of
Kentucky Bluegrass (Poa
) and other kinds of lawn grass at
this site, they ignored the coarse foliage of Inland Rush. This
selection effect, combined with infrequent mowing of the lawn, enabled
this rush to spread and establish itself.
The Inland Rush (Juncus
) is occasionally found in either
disturbed or poorly drained areas of prairies. It is a relatively small
and ordinary-looking rush that can be difficult to distinguish from
other rushes (Juncus spp.
especially the Path Rush (Juncus
and Dudley's Rush (Juncus
). The easiest way to distinguish
these rushes involves an examination of the membranous auricles
(uppermost margins) of their basal sheaths. The auricles of Inland Rush
are rounded and soft. In contrast, the auricles of Path Rush are
strongly exserted and narrowly triangular in shape, while the auricles
of Dudley's Rush are rounded and hardened. There is a tendency for the
Path Rush to be slightly smaller in size, while Dudley's Rush tends to
be slightly larger in size. The mature seed capsules of Inland Rush
tend to be more oblongoid in shape than those of the other two rushes.