Juncus acutus subsp. leopoldii (Parl.) Snogerup
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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. South Africa. Sommerset, Stellenbosch, Ecklon & Zeyer 4308 (lectotype, Fl, n.v., selected by Snogerup, 1993; isotypes, S, W, n.v.).
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Synonyms
Juncus leopoldii Parl., Juncus acutus var. sphaerocarpus Engelm., Juncus robustus S.Watson, Juncus acutus f. xanthosus Jeps.
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Description
Subspecies Description - Perennial densely cespitose herbs, 50-150 cm tall. Rhizome densely branching and producing shoots in axils of foliar leaves so the base of the plant is thickened. Culms rigidly erect, terete, 2-5 mm diam., longitudinally striate, heavily sclerified, pith parenchymatous with vascular bundles spread throughout the x.s. Leaves 40-120 cm long, 5-7 to each culm, all basal; sheaths 5-30 cm long, with narrow membranous margins gradually tapering upward and terminating into a narrow, few-centimeters-long adaxial groove; blades terete, rigid with hard spine-like apices, pith parenchymatous with vascular bundles spread throughout the x.s. Inflorescence compound paniculate, congested and only 3 x 3 cm or more lax and up to 20 x 10 cm, the branching alternating between short-shoots and long-shoots so the inflorescence often becomes subdivided, flowers clustered together in glomerules of 2-4 flowers each and clasped by the bract supporting the base of the pedicel, but without bracteoles inserted on the pedicel. Lower inflorescence bract half as long as or equalling the inflorescence, more rarely longer, rigidly erect with a wide sheath and a terete, hard-pointed blade. Tepals ca. 2 mm long, outer ones acute to obtuse with scarious margins terminating in two small auricles, V-shaped in x.s., inner ones mucronate to obtuse with large scarious auricles, U-shaped in x.s. Stamens 6, 1.5-2 mm long, equal to or slightly longer than the tepals; filaments short and widened at the base; anthers several times as long as the filaments, red brown. Style ca. 0.5 mm long. Stigmas 1 mm long. Capsule about twice as long as tepals, obovoid to almost globular, short mucronate, round in x.s., 3.5-4 x 3-3.5 mm, light to dark brown, 3-septate. Seeds usually somewhat curved, 0.9-1.1 x 0.3-0.4 mm, with transparent extensions of the outer seed coat at both ends.
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Discussion
Distribution and Ecology: Juncus acutus subsp, leopoldii occurs in South Africa, South America, southwestern North America, and the Atlantic Islands. It differs from the mostly Mediterranean Juncus acutus subsp, acutus in having obovoid, blunt, usually dark brown to chestnut-colored capsules (Snogerup, 1978). The North American populations, traditionally referred to as Juncus acutus var. sphaerocarpus, occur along the Californian coast from San Luis Obispo County southward to Isla Cedros of Baja California and inland to the Colorado Desert and Arizona. There is a disjunct occurrence in Puebla, Mexico. The South American populations occur in the Andean salt deserts from Atacama in northern Chile to Mendoza and Rio Negro in Argentina, and also in the coastal salt marshes on the east coast from Florianopolis in Santa Catarina, Brazil, to Bahia Blanca in Argentina. The neotropical occurrences therefore include no more than the 'inner margin' of a temperate and subtropical north-south disjunction.
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Distribution
Mexico North America| Puebla Mexico North America| Chile South America| Antofagasta Chile South America|