Sedge family (Cyperaceae)
Description: This native perennial plant is 2-4' tall and unbranched. The culms are green or dark green, glabrous, and terete; each culm has 5-10 alternate leaves along its length. The leave blades are up to 10" long and 1/3" across; they are green, dark green, or yellowish green. The leaf blades curve upward near the culm and spread outward or downward toward their tips. The upper surface of leaf blade is glabrous and often indented along its central vein, while the lower surface is hairless. The leaf sheaths are green or dark green, glabrous, finely ribbed, and closed; each sheath has a small V-shaped opening near its apex. The central culm terminates in a compound umbel of floral spikelets that spans up to 8" across. The branches and branchlets of this inflorescence are slender, green, and hairless; they are also strongly nodding or drooping. At the base of the inflorescence, there are about 3 leafy bracts that are variable in length; they can be longer or shorter than the inflorescence. There are also smaller membranous bracts at the base of each umbellet of spikelets. Each spikelet occurs individually on its own branchlet; the spikelets are not arranged in sessile heads. Each spikelet is about 6-10 mm. (1/41/3") in length and about one-third as wide; it is oblongoid or oblongoid-ovoid in shape, greenish brown, and somewhat bristly in appearance because of the exerted styles of the florets. Each spikelet consists of a dense head of florets and their outer scales. Each scale is about 2 mm. in length and lanceolate or lanceolate-ovate in shape; it is brown, except for a broad central vein that is green. Each floret has 3 stamens, a tripartite style, and an ovary. The blooming period occurs during the summer. Pollination is by wind. With maturity, each floret produces a single achene that is about 1 mm. long. This achene is light brown, bluntly 3-angled, ovoid or obovoid in shape with a short beak at its apex; it is surrounded by 5-6 fine bristles that are about the same length as the floral scales (2 mm.). The achenes are small enough to be blown about by the wind and they probably float on water. The root system is coarsely fibrous. Small colonies of plants are occasionally formed.
Cultivation: The preference is full sun to light shade, wet to mesic conditions, and soil with organic matter to retain moisture. However, it tolerates rocky ground if there is sufficient moisture. In sunny areas that are too dry, the leaf blades often become yellowish green.
Range & Habitat: Nodding Bulrush is common in most areas of Illinois; in the NW section of the state, it is occasional (see Distribution Map). Habitats include openings in moist woodlands, powerline clearances in wooded areas, edges of woodland paths, sedge meadows, riverbottom prairies, wet dolomite prairies, marshes and seeps, borders of rivers and ponds, moist depressions in limestone glades, roadside ditches, and fields. Sometimes, this species is found in mesic black soil prairies, but this is atypical.
Faunal Associations: The caterpillars of Archanara oblonga (Oblong Sedge Borer Moth) and Archanara subflava (Subflava Sedge Borer Moth) bore through the culms of Scirpus spp. (Bulrushes) and other members of the Sedge family. The seedheads of Bulrushes are an important source of food to ducks and some other birds (see the Bird Table for a listing of these species). The foliage is eaten by Canada Geese and Trumpeter Swans, while the culms and rootstocks are eaten occasionally by muskrats. Meadow Voles gnaw on the seedheads.
Photographic Location: A powerline clearance at Busey Woods in Urbana, Illinois.
Comments: Nodding Bulrush has attractive foliage and a rather elegant drooping inflorescence. To a greater extent than many other Scirpus spp. (Bulrushes), this adaptable species often occurs in woodlands and other surprisingly dry areas, although it also occurs in wetlands. Nodding Bulrush can be distinguished from many other Bulrushes by its flat leaf blades and drooping inflorescence. The spikelets of Nodding Bulrush occur individually at the tips of its branchlets, while Scirpus cyperinus (Wool Grass) and other Bulrushes with a similar appearance have sessile clusters of spikelets at the tips of their branchlets. The spikelets of Nodding Bulrush are oblongoid and about 3 times longer than they are across. In contrast, the spikelets of other Bulrushes are often ovoid and less elongated in appearance. Another important distinction is the appearance of the floral scales during the period of bloom: each scale of Nodding Bulrush has a conspicuous central vein that is green, while the scales of other Bulrushes usually have inconspicuous central veins.