Juncus nodosus L.
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Authority
Balslev, Henrik. 1996. Juncaceae. Fl. Neotrop. Monogr. 68: 1-167. (Published by NYBG Press)
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Family
Juncaceae
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Scientific Name
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Type
Type. America septentrionalis sent to Linnaeus by Kalm, most probably from Canada (Engelmann, 1868) (LINN, n.v.).
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Synonyms
Juncus rostkovii E.Mey., Juncus nodosus var. vulgaris Torr., Juncus nodosus var. genuinus Engelm., Juncus nodosus var. proliferus Lunell, Juncus nodosus var. meridianus F.J.Herm.
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Description
Species Description - Perennial herbs, 10-30 cm tall. Rhizome horizontal, stoloniform, long-creeping, 0.5-1 mm diam., often with bulbous thickenings at the base of the culms, internodes up to 7 cm long, scales absent or few. Culms erect, 0.5-1.5 mm diam., smooth. Cataphylls 0-2 to each culm, up to 4 cm long, inconspicuous. Foliar leaves (l-)2-4(-6) spaced along the culms or sometimes a few clustered at the base, (2-) 10-25 cm long; sheaths 1.5-5 cm long, with scariose margins terminating in two (0.5-)l-2 mm long, rounded auricles; blades 0.5-1 mm diam., terete, hollow, with usually inconspicuous septa 15 mm apart, adaxially grooved almost throughout. Inflorescence compound, anthelate, up to 8 x 4 cm, flower heads (l-)3-5(-7), globose, 8-12 mm diam., (5-)15-25(-30)-flowered, light green to stramineous or sometimes with slight red pigmentation, principal branches up to 6 cm long and 1 mm diam. Lower inflorescence bract (1.5-)5-15 cm long, resembling a cauline leaf with 0.5-1 cm long sheath, distal bracts shorter. Tepals equal, 2.8-4.5 mm long, linear-lanceolate, subulate, outer tepals concave, inner tepals flat. Stamens 3 or 6, 1.2-1.6 mm long; filaments flat; anthers oblong to linear, 0.5-0.7 mm long, usually as long as or shorter than the filaments, before anthesis sometimes slightly longer than the filaments. Capsule narrowly ovoid, gradually tapering into a clearly set off, 0.5 mm long beak, trigonous, 3-4.7 mm (incl. beak) x 0.7-1.3 mm, obviously longer than the tepals when mature, light to dark brown, unilocular. Seeds ellipsoid, apiculate, 0.4-0.5 x 0.2-0.25 mm, reticulate, yellowish brown.
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Discussion
Juncus nodosus is closely related to J. torreyi Coville and J. texanus (Engelmann) Coville. A derived common character of these three species, originally considered varieties of J. nodosus, is their stoloniform rhizomes with long internodes and bulbs or knobs at the bases of the culms, a feature I have not observed in other species of Juncus. Juncus texanus occurs in the Texas lowlands and is distinct from J. nodosus in its larger size, its long anthers which are always much longer than the filaments, and the long beak which makes its capsule subulate and narrower than that of J. nodosus. Juncus torreyi occurs in most of U.S.A. and S Canada and is even larger than J. texanus. It may be distinguished by its very large flower heads, each with 40-50 flowers.
Distribution and Ecology: Juncus nodosus is a temperate North American species, distributed from Newfoundland along the east coast of U.S.A. to West Virginia and across the continent through N U.S.A. and S Canada into the Rocky Mountains, but apparently not reaching the west coast of the continent. Isolated populations occur in N Canada, Alaska, and Texas and in the Sierra Madre and the Mexican plateau. In Mexico it grows in wet places at elevations of 500-2100 m.
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Distribution
Mexico North America| Durango Mexico North America| México Mexico North America| Michoacán Mexico North America| Nuevo León Mexico North America| Puebla Mexico North America| San Luis Potosí Mexico North America|