Juncus bufonius L.  
Family: Juncaceae
toad rush,  more...
Juncus bufonius image
Max Licher  
Herbs, annual, cespitose, 0.5--4 dm. Culms 1--many, occasionally becoming decumbent. Cataphylls 0--2. Leaves basal and cauline; auricles rudimentary or absent; blade flat, 3--13 cm x 0.3--1.1 mm. Inflorescences loose and diffuse or less often compact, usually at least ½1/2 total height of plant; primary bract shorter than inflorescence. Flowers: bracteoles 2; tepals greenish, lanceolate, 3.8--7(--8.5) mm; inner series slightly shorter, apex sometimes obtuse; stamens 3--6, filaments (0.7--)1--1.8 mm, anthers 0.3--0.8 mm; style 0.1--0.2 mm. Capsules tan to reddish brown, 3-locular, ellipsoid to narrowly so, slightly truncate, 2.7--4 x 1--1.5 mm, sometimes exceeding inner tepals but usually not outer series. Seeds yellowish, widely ellipsoid to ovoid, 0.26--0.49, not tailed. 2n = 27--37, 58--81, 108--115. Flowering and fruiting spring--early fall. Moist soils in meadows, along lakeshores or stream banks, ditches, or roadsides, especially frequent in drawdown areas; usually in open sites and often becoming weedy; Greenland; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; nearly worldwide. Nearly worldwide, Juncus bufonius is found essentially throughout North America except north of the Alaskan and Canadian tTaiga. Juncus bufonius is a highly polymorphic complex that is poorly understood systematically. Insufficient evidence exists upon which to base the segregation of the plethora of taxa that have been recognized out of this group in the past.

Notes: grass-like plant of moist places References: J.C. Hickman, ed. The Jepson Manual.W.B. McDougal. Seed plants of Northern Arizona. ASU specimens.
Annual grasslike forb 5 - 40 cm tall Leaves: few to several, both basal and alternate on stem, 3 - 13 cm long, 0.3 - 1.1 mm wide, linear, grasslike, flattened in cross section, without crosswise partitions inside (non-septate), as well as lacking ear-like appendages (auricles) at the top of the leaf sheaths. Inflorescence: a terminal, relatively elongate (at least half the total height of plant), loose and widely spreading, branched structure with several, single, short-stalked, radially symmetric, small flowers scattered along the branches. The entire branched inflorescence is subtended by a bract (usually shorter than full inflorescence), and the individual short-stalked flowers have two small (1 - 2.5 mm) bracts (bracteoles) positioned directly below the tepals. Stamens: three to six, with 0.7 - 1.8 mm long filaments, and usually shorter anthers (0.3 - 0.8 mm). Pistil: with one superior ovary, a 0.1 - 0.2 mm long style, and three stigmas. Fruit: three-chambered, tan to reddish brown, 2.7 - 4 mm tall (rarely longer than outer tepals), 1 - 1.5 mm wide, narrowly ellipsoid, fairly blunt-tipped capsules. Stems: tufted, ascending or sometimes more decumbent, round in cross section, and arising from fibrous roots. Seeds: many, yellowish, 0.26 - 0.49 mm long, widely ellipsoid to egg-shaped with short-pointed or abruptly narrowed tips, but without distinct narrowed tails at the ends. Tepals: six in two whorls of three, greenish with transparent or membranous edges, 3.8 - 8.5 mm long (outer three slightly longer than inner three), lance-shaped, sometimes with blunt tips.

Similar species: Juncus bufonius is quite unique due to its annual life cycle, fibrous roots instead of rhizomes, relatively small size (often under 10 cm), and the absence of ear-like appendages (auricles) at the top of the leaf sheaths. Although superficially J. marginatus may appear similar, it differs by having knotted rhizomes, always only three stamens, and the flowers are grouped in small clusters. Species in the same subgenus as J. bufonius (i.e. subgenus Poiophylli) differ because they are perennials, typically taller than 10 cm (with much shorter inflorescences compared to the total plant height), and some either have obvious small ear-like appendages (auricles) at the summits of the leaf sheaths, while others have leaf blades that are nearly round in cross section.

Flowering: June to September

Habitat and ecology: Occasional, typically in wet sands or silty soils, especially on pond shores, but also in compacted soils along paths or in vehicle tracks.

Occurence in the Chicago region: native

Notes: This is the only annual species of Juncus in our area. In the Chicago Region, this plant is consistently less than 15 cm tall.

Author: The Field Museum

Juncus bufonius image
Max Licher  
Juncus bufonius image
Juncus bufonius image
Juncus bufonius image
More Images        Web Links       View Parent Taxon       Close window