Crawe's Sedge
Carex crawei
Sedge family (Cyperaceae)
Description:
This perennial sedge consists of solitary plants about 4-14" tall.
The culm (central stem) of each plant is light green, glabrous, and
bluntly 3-angled; this culm is usually unbranched, but on rare
occasions it may divide into 2 parts. Along the culm, there are 2-5
widely spaced leaves (or leafy bracts) along its entire length; the
blades of these leaves (or bracts) are arching or ascending. Individual
blades are up to 5" long and 1.5–4.5 mm. across; they are light green,
glabrous, and often furrowed along the middle. The leaf sheaths are
light green, glabrous, and relatively tight. The culm terminates in an
inflorescence consisting of a terminal staminate spikelet, 2-4
pistillate spikelets, and the leafy bracts of the latter spikelets. At
the bases of these leafy bracts, the solitary pistillate spikelets
occur; these spikelets are sessile or they have very short peduncles
(less than 3 mm. in length), and they are erect or ascending.
Sometimes, the lowest pistillate spikelet is located near the ground at
the base of the plant. When the culm of this sedge divides into 2
parts, it produces 2 solitary staminate spikelets and 2 sets of upper
pistillate spikelets. Individual pistillate spikelets are up to 1¼" (3
cm.) long, about 4-6 mm. across, and cylindrical in shape.
The
perigynia (sac-like membranes covering the achenes) are densely packed
together on all sides of each pistillate spikelet; these perigynia are
oriented horizontally or slightly upward in relation to the central
axis of this spikelet. Individual perigynia are about 2.5–3.5 mm. long,
1.5–2.0 mm. across, and glabrous; they are broadly ellipsoid in shape
with very short beaks at their tips. Immature perigynia are
light green, but they become golden yellow to brown as they mature. The
pistillate scales are 1.5–3.0 mm. long and about one-half as much
across; they are ovate in shape, tapering to acute tips. These scales
are shorter than the perigynia. The terminal staminate spikelet is up
to 1¼" (3 cm.) long and very narrow; after blooming, it soon turns
brown. The staminate spikelet has an erect peduncle (floral stalk) that
is ½–4" long;
it is held above the uppermost pistillate spikelet. The blooming period
occurs from late spring to mid-summer, lasting about 1-2 weeks for
individual plants; the florets are cross-pollinated by the wind. The
achenes of this plant are about 1.5–2.0 mm. long and 1.0–1.5 mm.
across; they are bluntly 3-angled and obovoid-ellipsoid in shape. The
root system is fibrous and long-rhizomatous. Clonal colonies of plants
are often formed from the rhizomes.
Cultivation:
The preference
is full sun, wet to moist conditions, and either very sandy or rocky
soil that is calcareous. Temporary flooding is tolerated. This sedge
will not tolerate much competition from other plants. Cool to warm
summer weather is preferred.
Range
& Habitat: The native Crawe's Sedge is
found primarily in NE
Illinois, where it is rare (see Distribution
Map). At one time, Crawe's
Sedge was considered 'threatened' in Illinois, however its status has
changed with the discovery of additional populations of this plant. It
is has a wide distribution in the United States and Canada. In
Illinois, habitats of this sedge include wet marly sand, interdunal
depressions where moisture accumulates, moist sand flats, margins of
beach pools, calcareous seeps, and wet dolomite prairies. Outside of
the state, it is sometimes found growing in the cracks of alvars
(limestone pavement) near the Great Lakes. It also occurs sparingly in
White Cedar fens. This sedge is normally found in high quality natural
areas.
Faunal Associations:
Crawe's Sedge and other wetland sedges (Carex spp.)
are a source of food for such insects as leaf beetles (Plateumaris
spp.), billbugs (Sphenophorus spp.), the
larvae of leaf-miner flies (Cerodontha spp.), aphids
(Allaphis spp., Iziphya spp., Subsaltusaphis
spp.), leafhoppers (Cosmotettix spp.), the
larvae of skippers (Euphyes spp., Poanes
spp.), and sedge grasshoppers (Stethophyma spp.).
The seeds and/or seedheads of sedges are eaten by ducks, rails, some
species of sandpipers, upland gamebirds, and granivorous songbirds
(Martin et al., 1951/1961). Muskrats occasionally feed on their roots
and young sprouts.
Photographic Location:
Wet marly sand near Lake Michigan in NE Illinois.
Comments:
This is a small sedge that is rarely encountered, except in highly
specialized habitats. Crawe's Sedge (Carex crawei)
resembles the more common Meadow
Sedge (Carex granularis) to some extent because of
the similar
appearance of their pistillate spikelets, and sometimes they can be
found growing in the same habitats. Crawe's Sedge differs from the
latter sedge by its more narrow leaves (less than 5 mm. across),
tendency to form loose colonies of leafy culms rather than dense tufts
of leafy culms, and by its production of terminal staminate spikelets
on long peduncles (floral stalks), rather than short peduncles or
no peduncles. Another distinctive characteristic is the tendency of
Crawe's Sedge to produce its lowest pistillate spikelet close to the
ground. Both Meadow Sedge and Crawe's Sedge belong to the Granulares
Section of sedges (Carex spp.).