* Leaves none; barren and fertile stems subulate, with sheathing scales at the bane.
† Panicle lateral.
J. communis: stems leafless, densely tufted, cylindrical, 2-4 feet high, erect but soft and pliable, sheathed at the base by a few brown scales; some barren resembling leaves, others bearing towards the top a panicle of flowers; the flowers brown in close dense clusters (J. conylomeratus), or paler in loose open panicles (J. effusus); perianth-segments very pointed; capsule about as long, very obtuse or even notched. - Wet situations. Fl. July.
J. glaucus: stems seldom two feet high, thin, hard, stiff, often glaucous; panicle erect, loose, branched; perianth-segments lanceolate-subulate; capsule shining brown, rounded or almost pointed. - Wet places. Fl. July, August.
†† Panicle terminal.
J. maritimus: stems 2-3 feet high, tufted, rigid, and sharp-pointed; flowers numerous, in loose, irregularly compound panicles; perianth-segments lanceolate, acute; capsule elliptical, rather shorter. - Maritime sands. Fl. July, August.
J. acutus: stems 3-6 feet high, very rigid, prickly-pointed; flowers numerous, in compound panicles; capsule roundish-ovate, considerably longer than the perianth-segments. - Maritime sands. Fl. July, August.
** Stems all leafy. † Leaves rounded or subcompressed, jointed internally.
J. articulatus: stems erect, 1-3 feet higli; leaves sheathing the stem below, cylindrical upwards, hollow, but divided inside by cross partitions of pith, which give them the appearance of being jointed; flowers in little clusters, arranged in a compound terminal panicle; perianth-segments all pointed, or the inner ones obtuse; capsule more or less pointed. - Boggy places. Fl. June to August.
J. obtusiflorus differs only from the common larger erect form of J. articulatus in having all the segments of the perianth obtuse or nearly so, and about as long as the very pointed capsule. - Marshes, rather rare.
†† Leaves grooved above, not jointed internally.
J. compressus: stems 1-1 1/2 foot high, erect, rather slender, with a few nearly radical leaves shorter than the stem, and 1-2 higher up, all narrow and grooved; flowers scarcely clustered, in a loose terminal panicle, shining brown; perianth-segments obtuse; capsule roundly-ovate, about as long. - Wet marshy places, especially near the sea. Fl. June to August.
J. bufonius: annual; stems numerous, forming dense tufts, 1 - 8 inches high, branching and flowering almost from the base; leaves chiefly radical, short, slender, angular, grooved; flowers solitary along the branches, the lower bracts leaf-like; perianth-segments narrow, pointed, pale-green, with scarious edges; capsule oblong, shorter. - Wet places. Fl. July, August.
*** Leaves all radical, numerous.
J. squarrosus: leaves all radical or nearly so, short, numerous, very narrow, grooved, stiff, spreading; flower-stem nearly a foot high, rigid, with a terminal panicle; flowers usually distinct; perianth-segments rather broad, glossy brown, with broad scarious edges. - Moors and heaths. Fl. June, July.