Robert H. Mohlenbrock. USDA SCS. 1989.
Midwest wetland flora: Field office illustrated guide to plant species
. Midwest National Technical Center, Lincoln. Provided by USDA NRCS Wetland Science Institute (WSI).
slender yard rush
This plant can be weedy or invasive according to the authoritative sources noted below.This plant may be known by one or more common names in different places, and some are listed above. Click on an acronym to view each weed list, or click here for a composite list of
Weeds of the U.S.
Willdenow, Sp. Pl. 2(1): 214. 1799.
Juncus bicornis Michaux; J. bicornis var. williamsii (Fernald) Victorin; J. macer Gray; J. macer forma williamsii (Fernald) F. J. Hermann; J. macer var. williamsii (Fernald) Fernald; J. tenuis var. bicornis (Michaux) E. Meyer; J. tenuis var. multicornis E. Meyer; J. tenuis var. williamsii Fernald
Herbs, perennial, tufted, 1.5--5 dm. Rhizomes densely branching. Culms few--20. Leaves basal, (1--)2--3; auricles 2--5 mm, apex acute, membranous; blade flat, 3--12 cm x 0.5--1 mm, margins entire. Inflorescences 5--40-flowered, borne congested or branch internodes ca. as long as tepals, ssomewhat loose, 1--5 cm; primary bract usually longer than inflorescence. Flowers: bracteoles 2; tepals greenish, lanceolate, 3.3--4.4 mm; outer and inner series nearly equal; stamens 6, filaments 0.5--0.9 mm, anthers 0.1--0.2 mm; style 0.1--0.2 mm. Capsules tan or light brown, 1-locular to pseudo-3-locular, ellipsoid, (3.3--)3.8--4.7 x (1.1--)1.3--1.7 mm, nearly equal to tepals. Seeds tan, ellipsoid to lunate, (0.52--)5.5--0.65(--0.7) mm, not tailed. 2n = 80.
Flowering spring--early summer. Exposed or shaded sites in soils ranging from sandy to clayey under moist or drier conditions, oftentimes these sites naturally or otherwise disturbed (e.g., game or human trails); Alta., B.C., Man., N.B., N.S., Ont., P.E.I., Que., Sask.; 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.; introduced worldwide.
Juncus tenuis occurs throughout North America. It is particularly abundant in northeastern United States and eastern Canada, although infrequent in the south and west.
Through the use of isozyme electrophoresis, hybridization can be demonstrated between various members of the Juncus tenuis complex, including Juncus tenuis, J. anthelatus, J. interior, J. secundus, and J. dichotomus (R. E. Brooks, unpubl.). Juncus ××oronensis is thought to be a hybrid between J. tenuis and J. vaseyi in the northeast.
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