Juncus gerardii Loisel.

Foodplant / saprobe
half-encircling colony of Arthrinium dematiaceous anamorph of Arthrinium cuspidatum is saprobic on stem of Juncus gerardii

Foodplant / open feeder
larva of Dolerus taeniatus grazes on leaf of Juncus gerardii
Other: sole host/prey

Of all Dutch native 'true' rush species, saltmarsh rush tolerates the most brackish or salty environments. The plant lives up to its name. In fact, you aren't even likely to find it in freshwater environments, unless there are remnants of salt still in the soil. Saltmarsh rush falls under the category of rushes that blossom at the top of the stem with more or less individual flowers. Red knob-like galls from the leaf-flea are often found on the stem of saltmarsh rush. Livestock will eat it as well, however they prefer red fescue or creeping bent-grass which grow along side this rush. So if there is a lot of grazing, saltmarsh rush will get the chance to dominate the vegetation.

Herbs, perennial, 2--9 dm. Rhizomes long- creeping. Cataphylls 1--3. Leaves basal, (1--)2--4; auricles 0.4--0.6(--0.8) mm, scarious; blade flat or somewhat channeled,,10--40 cm x  0.4--0.7 mm, margins entire. Inflorescences 10--30(--80)-flowered, usually loose and somewhat lax, 2--16 cm; primary bract rarely surpassing inflorescence. Flowers: bracteoles 2; tepals dark brown or blackish, lanceolate-ovate to oblong, 2.6--3.2(--3.8) mm; inner and outer series nearly equal, apex obtuse; stamens 6, filaments 0.4--0.7 mm, anthers 1.1--1.6(--1.8) mm; style 0.4 mm. Capsules chestnut brown or brown, 3-locular, widely ellipsoid, (2.2--)2.5--3.2(--3.5) x 1.3 -- 1.9 mm. Seeds dark brown, ellipsoid to lunate, 0.485--0.6(--0.67) mm, not tailed. 2n = ca. 80, 84.

Flowering and fruiting late spring--summer. Forming extensive colonies in exposed coastal estuary meadows and salt marshes just above high- tide line; also inland; Greenland; St. Pierre and Miquelon; B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., Oreg., P.E.I., Que.; Colo., Conn., Del., Ill., Ind., Kans., Ky., Maine, Md., Mass., Mich., Minn., Mo., N.H., Mont., N.J., N.Y., N.Dak., Ohio, Oreg., Pa., R.I., Utah, Vt., Va., Wash., Wis.; Europe; Asia.

Juncus bulbosus Linnaeus var. gerardii (Loiseleur-Deslongchamps) A. Gray; J. fucensis H. St. John; J. gerardii var. pedicellatus Fernald