Panicled Bulrush

Scirpus microcarpus occasionally hybridizes with S. expansus, particularly in New England.

Populations of Scirpus microcarpus from eastern United States have been treated as a distinct species, S. rubrotinctus Fernald. Populations from the central part of the continent are intermediate for the characters Fernald used to separate S. rubrotinctus. The taxonomy of the group should be reinvestigated. Populations from the Queen Charlotte Islands (British Columbia) have a different chromosome number (2n = 64; R. L. Taylor and G. A. Mulligan 1968) than populations from New York and Pennsylvania (2n = 66; A. E. Schuyler 1967, 1976).

Plants spreading; rhizomes reddish, long, with conspicuous nodes and internodes. Culms: fertile ones upright or nearly so; nodes without axillary bulblets. Leaves 4–11 per culm; sheaths of proximal leaves red; proximal sheaths and blades with septa few to many, conspicuous or inconspicuous; blades 23–60(–75) cm × 5–15(–20) mm. Inflorescences terminal; rays divaricate or ascending, proximal branches almost smooth, distal branches scabrous, rays without axillary bulblets; bases of involucral bracts green, black, or red, not glutinous. Spikelets in dense clusters of (1–)3–18 (largest cluster with 6 or more spikelets), spikelets sessile, 2–8 × 1–3.5 mm, ovoid or narrowly ovoid; scales green or black, broadly ovate or ovate to broadly elliptic or elliptic, 1.1–3.4 mm, apex rounded to acute or apiculate or occasionally mucronate, apiculus or mucro (if present) to 0.2 mm. Flowers: perianth bristles persistent, (3–)4(–6) per flower, stout, straight or curved, shorter than to 1.5 times as long as achene, with retrorse, thick-walled, sharp-pointed teeth densely arranged almost to base, enclosed within (occasionally weakly projecting from) scales; styles 2(–3)-fid. Achenes almost white, ovate to obovate in outline, biconvex to plano-convex, 0.7–1.6 × 0.8–1 mm. 2n = 64, 66.

St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Alaska, Ariz., Calif., Colo., Conn., Idaho, Ill., Ky., Maine, Mass., Mich., Minn., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.Dak., Oreg., Pa., R.I., S.Dak., Utah, Vt., Wash., W.Va., Wis., Wyo.; Mexico (Baja California); e Asia (Kamchatka Peninsula).

Fruiting early summer (Jun–Jul).

Marshes, moist meadows, ditches; 0–2900m.

Scirpus microcarpus var. rubrotinctus (Fernald) M. E. Jones; S. rubrotinctus Fernald; S. rubrotinctus var. confertus Fernald; S. sylvaticus Linnaeus var. digynus Boeckeler

Scirpus microcarpus Presl, Rel. Haenk. 1: 195. 1828
Scirpus lenticularis Torr. Ann. Lye. N. Y. 3: 328. 1836.
Scirpus sylvaticus /3 digynus Bock. Linnaea 36: 727. 1870.
Scirpus sylvaticus var. microcarpus MacM. Metasp. Minn. Valley 97. 1892.
Scirpus Macounii Holm, Am. Jour. Sci. IV. 18: 21. 1904.
Scirpus microcarpus var. longispicatus M. E. Peck, Proc. Biol. Soc. Wash. 47: 185. 1934.
Stout perennial 0.5-1.3 m. tall, erect from thick rhizomes; leaves up to 1 m. long, often exceeding the culm, the sheaths mostly green but often tinged with red, the blades 0.5-2.5 cm. broad, green, often nodulose, strongly scabrous on the margins and midrib; involucral bracts 3-many, to 1.5 cm. broad, leaflike, variable in length, equaling but not exceeding the mature inflorescence; inflorescence spreading, compound-umbellate, the primary rays to 2 dm. long, terete or angled, obscurely scabrous, the secondary branches usually ca. 5 cm. long, the tertiary shorter and capped by 3-8 spikelets; spikelets greenish-black, mostly 3-5 mm. long, 2 mm. broad, lanceolate-acute; style bifid, brick-red; bristles 4-6, whitish, fragile, obscurely scabrous, exceeding the achene; achene 1.25-1.5 mm. long, white, lenticular, apiculate.
Type locality: "In Nootka-Sund."
Distribution : Moist shady banks ; Alaska, south to New Mexico and California.

Scirpus rubrotinctus Fernald, Rhodora 2: 20. 1900
Scirpus microcarpus var. robrotinctus M. E. Jones, Bull. Univ. Mont. Biol. 15: 20. 1910.
Scirpus rubrotinctus var. conferttis Fernald, Rhodora 2:21. 1900.
Scirpus avatshensis Kom. Repert. Sp. Nov. 13: 163. 1914.
Scirpus microcarpus var. conferlus House, Bull. N. Y. State Mus. 233-234: 62. 1921.
Scirpus rubrotinctus f. conferlus Weath. Bull. Conn. Geol. Nat. Hist. Surv. 48: 29. 1931.
Scirpus rubrotinctus f. radiosus Fernald, Rhodora 45: 295. 1943.
Perennial from stout, reddish stolons; roots fibrous; culm rather stout, 4-9 dm. high, 0.5-1.5 cm. thick at the base, green, triangular, smooth; leaves to 12 mm. broad, the upper equaling or slightly exceeding the inflorescence, the sheaths mostly red-tinged at the base, the blades scabrous on the margins only, tapered to a rounded tip; involucral leaves mostly 3, the longest equaling or exceeding the inflorescence, strongly scabrous on the margins; rays numerous, the 3-5 longest 0.5-1.5 dm. long, stiff, ascending, subequal, the many shorter ascending and divergent; spikelets 4-9 mm. long, ovoid to cylindric, iu glomerules of 3-many; scales 1.5-2 mm. long, ovate, blunt or somewhat mucronate, the weak midrib green or white, the margins greenish-black; bristles 6, whitish, stiff, retrorsely scabrous, equaling or slightly exceeding the achene; style bifid, reddish; achene 0.75-1 mm. long, white, oval, lenticular, slightly apiculate.
Type locality: Foxcroft, Maine.
Distribution: Damp soil; Newfoundland, south to New Jersey and west through the Great Lakes to Colorado, Idaho, and British Columbia.

Scirpus microcarpus, 3 plants flowering at stream edge

Scirpus microcarpus is a species of flowering plant in the sedge family known by the common names panicled bulrush, smallfruit bulrush, and barberpole bulrush. It is native to North America, where it can be found throughout the northern and western regions, from Alaska across Canada to the northeastern United States, in most of the central and western states, and in Baja California. It grows in many types of moist and wet habitat. It is a perennial herb growing from a long rhizome system. The erect, three-angled stems often exceed one meter tall. Sheathing leaves occur at the stem bases as well as higher up the stems. The inflorescence is a panicle of many clusters of spikelets and leaflike bracts on long, thin branches. The fruit is a pale, smooth achene less than 2 millimeters long.