Jointed Rush

Foodplant / feeds on
larva of Aphanisticus emarginatus feeds on Juncus articulatus
Other: major host/prey

Foodplant / saprobe
apothecium of Cistella fugiens is saprobic on dead inflorescence of Juncus articulatus
Remarks: season: 12-10

Foodplant / saprobe
immersed, then revealed apothecium of Diplonaevia exigua is saprobic on dead Juncus articulatus
Remarks: season: 4-8

In Great Britain and/or Ireland:
Foodplant / gall
sorus of Entorrhiza casparyana causes gall of live, galled root of Juncus articulatus
Remarks: season: 8

Foodplant / saprobe
sessile, shielded apothecium of Micropeziza karstenii is saprobic on dead stem of Juncus articulatus
Remarks: season: 7-12
Other: unusual host/prey

Foodplant / saprobe
sessile apothecium of Mollisia juncina is saprobic on dead Juncus articulatus
Remarks: season: 5-9

Foodplant / saprobe
pseudothecium of Pleospora aquatica is saprobic on Juncus articulatus
Remarks: season: 10

Foodplant / saprobe
numerous, immersed, more or less linearly arranged, fuscous, covered pycnidium of Septoria coelomycetous anamorph of Septoria junci is saprobic on dead leaf tip of Juncus articulatus
Remarks: season: 2-10

Plant / associate
larva of Trichopsomyia flavitarsis is associated with galled Juncus articulatus

Foodplant / parasite
telium of Uromyces junci parasitises live Juncus articulatus
Remarks: season: 7 onwards

A widely distributed and very variable species, known to have: (i) several ecotypes (Clapham et al, Fl.Brit. Isles 990, 1962); (ii) larger forms with 80 chromosomes and up to 18 flowers in each head; (iii) and hybrid, with sterile capsules and usually 3-6 flowers in each head.

Juncus articulatus hybridizes with J. brevicaudatus (= J. ´ xfulvescens Fernald), J. alpinus (= J. ´ xalpiniformis Fernald), J. nodosus, and J. canadensis.

Juncus articulatus var. obtusatus Engelmann appears to be intermediate with J. alpinus. It has spreading inflorescence branches but obtuse inner tepals. This may represent a backcross with J. alpinus. Recent evidence suggests that J. alpinus is a polyploid species with J. articulatus as one of its parents.

Perennial, shortly rhizomatous, greenish herb, (10-) 15-50 (-80) cm tall, erect to almost prostrate, sometimes rooting from the lower nodes, non-stoloniferaus; stem terete, faintly sulcate with 2-6 cauline leaves. Leaves shorter than stem linear transversely 15-25 septate-nodose, subterete, green, usually 1-2 mm broad; basal sheaths usually brownish, auricled. Inflorescence terminal, often richly and somewhat dichotomously branched, with many shortly stalked heads, each consisting of (4)6-10(-12) flowers, 5-10 mm across; lowest bract erect, usually c. half as long as the inflorescence, leafy. Flowers (2-)2.5-3 mm long, brownish to greenish, sessile; perianth segments lanceolate, acute inner subobtuse with broad whitish margins. Stamens 6, much shorter than the perianth, with anthers c. as long as the filaments. Capsules 34 mm long, 1.5-2 mm broad, oblong-ovoid or ellipsoid, usually contracted abruptly into a short beak, conspicuously exceeding the perianth, brownish to greenish, often lustrous, many seeded (3040); seeds c. 0.4(-0.5) mm long, ovoid or ellipsoid, brownish 2n=80.

Herbs, perennial, rhizomatous to nearly cespitose, 0.5--6(--10) dm. Rhizomes 2--3 mm diam., not swollen. Culms erect to decumbent (and floating), terete, 1--3 mm diam., smooth. Cataphylls 1, maroon to straw-colored, apex acute to obtuse. Leaves: basal 0--2, cauline (1--)3--6; auricles 0.5--1 mm, apex rounded, scarious; blade green to straw-colored, terete, 3.5--12 cm x 0.5--1.1 mm. Inflorescences terminal panicles of 3--30(--50) heads, 3.5--8 cm, branches spreading; primary bract erect; heads 3--10-flowered, obpyramidal to hemispheric, 6--8 mm diam. Flowers: tepals green to straw-colored or dark brown, ovate to lanceolate, 1.8--3 mm; outer tepals with apex acute or acuminate; inner tepals with apex acute acuminate to obtuse; stamens 6, anthers equal to filament length. Capsules exserted ca. 1 mm beyond perianth, chestnut brown to dark brown, imperfectly 3-locular, ellipsoid or ovoid, 2.8--4 mm, apex acute proximal to beak, valves separating at dehiscence. Seeds obovoid, 0.5 mm, not tailed. 2n = 80.

Plants perennial, tufted or rhizome creeping, (10--)15--40(--60) cm tall. Stems terete, 0.8--1.5 mm in diam. Cataphylls absent to 2. Cauline leaves 2--6; leaf sheath auricles well developed, acute, free part ca. 2 mm, membranous; leaf blade terete or somewhat laterally compressed, 2.5--7.5(--10) cm × 0.8--1.4 mm, perfectly septate. Inflorescences usually broad; branches rigid, spreading; involucral bract erect to ascending, 0.7--3 cm; heads 5--30, hemispheric to toplike, 5--10(--15)-flowered. Perianth segments reddish brown with greenish midvein, lanceolate, 2.5--3 mm, subequal, apex acute. Stamens 6, 1/2--3/4 as long as perianth; filaments 0.7--0.9 mm; anthers oblong, 0.5--1 mm. Capsule dark brown, shiny, trigonous ovoid, 3--3.5 mm, apex sharply acute and tapered to a conspicuous tip. Seeds ovoid, 0.5--0.7 mm, reticulate. Fl. Jun--Jul, fr. Aug--Sep. 2 n = 80.

Temperate regions, W. Himalaya.

Distribution: Most of Europe, N. Africa, Central and S.W. Asia, to Pakistan and the Himalayas; eastern N. America; widely introduced reaching Australia and New Zealand.

Gansu, Hebei, Henan, Hubei, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Xinjiang, Xizang, Yunnan [Afghanistan, Bhutan, India, Kashmir, Mongolia, Nepal, Pakistan, Russia (E Siberia), Vietnam; Africa, Europe, North America].

St. Pierre and Miquelon; B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., Que., P.E.I.; Alaska, Ariz., Colo., Calif., Conn., Idaho, Ind., Ky., Maine, Mass., Mich., Minn., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., Ohio, Oreg., Pa., R.I., S.Dak., Utah, Vt., Va., Wash., W.Va.; Eurasia.

2300-3800 m

Fruiting mid summer--fall.

Wet meadows, sand, along rivers, edges of water along ditches; 1200--3700 m.

Wet ground in ditches, lake and stream margins, and a variety of other habitats, often a calciphile; 0--3000m.

Juncus lampocarpus Ehrhart ex Hoffmann; J. lampocarpus var. senescens Buchenau.

Juncus articulatus var. obtusatus Engelmann; J. articulatus var. stolonifer (Wohlleben) House; J. lampocarpus Ehrhart ex Hoffmann

Juncus articulatus is a flowering plant species in the rush family Juncaceae. It is known by the common name jointleaf rush or jointed rush, which can also refer to J. kraussii from Australia. It is native to Eurasia, Canada, Greenland, and much of the United States. It grows in moist areas, such as wet sand, and thrives in calcareous soils. J. articulatus was found to be more sensitive to drought and salt stress than its congeners J. acutus and J. maritimus. It is a perennial herb producing mainly erect stems from a short rhizome. The stem may root at nodes, and it generally has one or more flattened hollow cylindrical leaves up to 10 centimeters long. Transverse internal partitions or joints may be seen or felt in the leaf of the plant.

The inflorescence atop the stem has several branches with up to 25 clusters of up to 12 flowers each. Each individual flower has greenish to dark brown, pointed tepals 2 to 3 millimeters long, six stamens bearing anthers, and a protruding, feathery pistil. The fruit is a dark brown capsule with a pointed tip.