Juncus militaris Bigelow
Family: Juncaceae
Bayonet Rush
Juncus militaris image
Herbs, perennial, rhizomatous, 3--15 dm. Rhizomes 3--4 diam., nodes not swollen, smooth. (often developing filiform leaves in running water). Culms erect, terete to compressed, 5--12 mm diam. Cataphylls 1--3, straw-colored to pink, apex acute. Leaves: basal 0, cauline 2, long capillary leaves often found in fascicles on rhizomes; auricles 0.3--0.5 mm, apex rounded, scarious; blade terete, 50--70(--100) cm x 2--5 mm, those of proximal leaves usually overtopping inflorescences, distal leaves usually inflated bladeless sheaths, occasionally absent or with well-developed blades. Inflorescences terminal panicles of 20--100 heads, 4--15 cm, branches erect to ascending; primary bract erect; heads (3--)5--13(--25)-flowered, hemispheric to turbinate, 6--8 mm diam. Flowers: tepals straw-colored or reddish, lanceolate, 2.3--3.2(--4) mm, nearly equal, apex acuminate to awned; stamens 6, anthers 1.5--2 times filament length. Capsules straw-colored, 1-locular, ovoid, 2.3--3.3 mm, equaling perianth, tapering to subulate tip, valves separating at dehiscence. Seeds obovoid, 0.5--0.6 mm, not tailed; body clear yellow-brown. Fruiting late summer--fall. Mucky bottoms of shallow lakes and rivers, wet shores; 0--500 m; St. Pierre and Miquelon; N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I.; Conn., Del., Ind., Maine, Md., Mass., Mich., N.H., N.J., N.Y., Pa., R.I., Vt. The proximal culm leaf of Juncus militaris usually has a single well-developed leaf blade that overtops the inflorescence; and the distal leaf usually is an inflated bladeless sheath above it. An Alabama report, based on a single specimen collected by Drummond (not seen), at GH and MO, was discounted by Coville (and here). Coville believed the location and possibly the collector were wrongly attributed to this collection (see letter from Coville to Small at NY).

Perennial grasslike forb 0.5 - 1.5 m tall Leaves: usually one about mid-stem (but see below), stout, large, 0.5 - 1 m long (extending beyond inflorescence), 2 - 5 mm diameter, linear, grasslike, stiff, round in cross section, with distinct crosswise partitions inside (septate), and having a thin and papery, basal, 0.3 - 0.5 mm long, round-tipped, ear-like appendage (auricle) at the top of the leaf sheath. In many plants there are actually two leaves per stem, but it appears as only one leaf since the other leaf (leaves) has no expanded blade and is only represented as an inflated sheath, though occasionally it is absent or sometimes it may have a well-developed blade (though relatively short). Inflorescence: a terminal, 4 - 15 cm long, more or less ascending-branched structure with branches ending in 20 to 100, hemispheric to inversely conic, 6 - 8 mm diameter flower clusters. Each flower cluster is a compact head of three to twenty, tiny, radially symmetric flowers. Stamens: six, with very long anthers, which may be up to two times longer than the filaments. Pistil: with one superior ovary, and three stigmas. Fruit: single-chambered, straw-colored, 2.3 - 3.3 mm tall (about same height as tepals), three-angled, somewhat egg-shaped capsules with very slender-tapering, pointed, bristle-like tips. Stems: tufted, erect, smooth, round or compressed in cross section, robust, 0.5 - 1.2 cm diameter, and arising from 3 - 4 mm diameter rhizomes lacking swollen nodes. Seeds: many, clear yellow-brown, 0.5 - 0.6 mm long, inversely egg-shaped with short-pointed or abruptly narrowed tips, but without distinct narrowed tails at the ends. Tepals: six in two whorls of three, straw-colored or reddish, all about equal length (2.3 - 3.5 mm), lance-shaped with long-tapered, slender, pointed tips.

Similar species: Juncus militaris is hard to confuse with our other species due to its large size (usually at least 0.5 m tall), the very long and stiff lowest stem leaf blade that overtops the inflorescence, and the fact that it is confined to very specific and rare locations in the Chicago Region. Probably most similar would be J. alpinoarticulatus, J. articulatus, and their hybrid, J. x alpiniformis, but none of those taxa have the inflorescence overtopped by a stem leaf, and they are usually much smaller plants.

Flowering: late July to October

Habitat and ecology: Incredibly rare, in mucky bottoms of shallow lakes or wet shores.

Occurence in the Chicago region: native

Notes: Juncus militaris is a much more northern species and the two sites of occurrence in northern Indiana represent far disjunct populations. The next closest populations are probably in Michigan's Upper Peninsula or very north Lower Peninsula in counties bordering Lake Huron. Tragically, the one documented site in Porter County, Indiana was destroyed in the 1950's. It was thought to be extinct in the Chicago Region (state of Indiana listed this species as extirpated),until it was found at a nature preserve in St. Joseph County, Indiana in 1997 (specimen at MOR as displayed on this website).

Author: The Field Museum

Stems stout, erect from a rhizome, (3-)5-10 dm, with a few (or no) bladeless sheaths near the base and a single (seldom two) long foliage lf near the middle, its stout stiff blade overtopping the infl; rhizome, when submersed, often producing many long capillary lvs; infl obpyramidal, 4-15 cm, freely branched (the branches ascending), the obpyramidal to subhemispheric glomerules 5-13(-25)-fld; fls eprophyllate; tep lance-subulate to lanceolate, subequal, 2.3-3.5(-4) mm, the sep often aristulate; stamens 6; fr unilocular, trigonously ovoid-prismatic, 2.4-3.3 mm, acuminate into a conspicuous beak. Shallow water and wet shores; N.S. to Del.; inland in n. N.Y., s. Ont., and n. Mich. J. subnodulosus Schrank, a European species, was collected as a waif in Mass. many years ago and described as J. pervetus Fernald. It has obtuse tep and widely spreading primary branches of the infl.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.