Juncus effusus L.

Authority

Balslev, Henrik. 1996. Juncaceae. Fl. Neotrop. Monogr. 68: 1-167. (Published by NYBG Press)

Family

Juncaceae

Scientific Name

Juncus effusus L.

Type

Type. Europe, n.v.

Synonyms

Juncus bogotensis Kunth

Description

Species Description - Perennial, cespitose herbs, 50-100 cm tall. Rhizome creeping, 2-5 mm diam., covered with dark, castaneous scales, internodes very short and the culms arising in densely crowded rows. Culms erect, terete, 2-6 mm diam., externally striate by 4060 longitudinal, subepidermal sclerenchyma strands running parallel to the vascular bundles; pith continuous, aerenchymatous with asteriform cells. Cataphylls 3-5 to each culm, to 30 cm long, with rudimentary, acicular blade to 5 mm long, usually densely sheathing the base of the culm, dark castaneous at the base, light brown or stramineous upwards. Foliar leaves absent. Inflorescence pseudolateral, many-flowered, loosely branching and up to 10 x 20 cm, or usually smaller and sometimes congested, capitulate and only 1.5 x 1.5 cm, sometimes subdivided, compound cymose, consisting of several congested cymes, the ultimate ones being unilateral drepania. Lower inflorescence bract appearing as a continuation of the culm, 10-45 cm long, and usually constituting 1/5 or more of the total plant height (rarely only 1/10 in Costa Rica), smoothly jointed to the culm, sheath narrow, distal bracts scalelike or scariose. Each flower clasped by two 0.7-2 mm long bracteoles. Tepals unequal, lanceolate, 2-5 mm long, stramineous to castaneous, outer tepals concave, slightly longer than the flat inner tepals. Stamens 3, 1-2 mm long; anthers linear or oblong, 0.3-1 mm long, shorter than or equalling the filaments. Capsule ellipsoid to obovoid, obtuse, trigonous to 3-lobed, 1.5-5 x 1-2.5 mm, stramineous to castaneous, 3-septate. Seeds ovoid, asymmetrical, short apiculate, 0.4-0.6 x 0.2-0.3 mm, rugose, yellow to brown.

Discussion

In Mexico and Central America Juncus effusus commonly has a lax inflorescence with many stramineous, small flowers with the tepals as short as 2 mm. This agrees well with the North American J. effusus subsp, solutus (Fernald & Wiegand) Hámet-Ahti (Hamet-Ahti, 1980). In Costa Rica some collections of J. effusus have very short lower inflorescence bracts which occupy as little as 1/10 of the total plant height. The N Andean collections commonly have dense inflorescences of castaneous flowers with 3-3.5 mm long tepals and long lower inflorescence bracts that occupy at least 1/5 of the total plant height. This N Andean material has been called J. bogotensis in many herbaria. Collections from SE Brazil have small stramineous flowers like the Central American plants. The neotropical material thus exhibits quite different extremes, but, transitions between them being gradual, they are best treated as one variable species.

Distribution and Ecology: Juncus effusus is a cosmopolitan species, most common in the north temperate region but frequent at high elevations in the tropics and scattered in the south temperate region. Weimark (1946) presented a map of the total distribution of J. effusus. In the neotropical region, J. effusus occurs on the Antillean islands of Hispaniola and Guadeloupe, through the Mexican and Central American highlands as far as Costa Rica, in the Andes from Venezuela to Peru, Bolivia, and in Tucumán in Argentina, and also in the SE Brazilian highlands. It grows in pastures, along roads, and in ditches and other places under human influence. Near the equator it is found at elevations above 2000 m; north and south of the equator it is often found at lower elevations.

Common Names

totora, junco, totorilla, junco chiquito

Distribution

Mexico North America| Aguascalientes Mexico North America| Chiapas Mexico North America| Distrito Federal Mexico North America| Guanajuato Mexico North America| Hidalgo Mexico North America| Jalisco Mexico North America| México Mexico North America| Michoacán Mexico North America| Morelos Mexico North America| Oaxaca Mexico North America| Tabasco Mexico North America| Veracruz Mexico North America| Guatemala Central America| Alta Verapaz Guatemala Central America| Baja Verapaz Guatemala Central America| Huehuetenango Guatemala Central America| Jalapa Guatemala Central America| Quiché Guatemala Central America| San Marcos Guatemala Central America| Totonicapán Guatemala Central America| Honduras Central America| Gracias a Dios Honduras Central America| Intibucá Honduras Central America| La Paz Honduras Central America| Morazán Honduras Central America| Ocotepeque Honduras Central America| El Salvador Central America| Chalatenango El Salvador Central America| Costa Rica South America| Cartago Costa Rica Central America| Heredia Costa Rica Central America| Puntarenas Costa Rica Central America| San José Costa Rica Central America| Haiti South America| Guadeloupe South America| Colombia South America| Antioquia Colombia South America| Boyacá Colombia South America| Caldas Colombia South America| Cauca Colombia South America| Cundinamarca Colombia South America| Huila Colombia South America| La Guajira Colombia South America| Magdalena Colombia South America| Nariño Colombia South America| Norte de Santander Colombia South America| Putumayo Colombia South America| Risaralda Colombia South America| Santander Colombia South America| Tolima Colombia South America| Venezuela South America| Aragua Venezuela South America| Distrito Federal Venezuela South America| Lara Venezuela South America| Mérida Venezuela South America| Táchira Venezuela South America| Trujillo Venezuela South America| Zulia Venezuela South America| Ecuador South America| Azuay Ecuador South America| Carchi Ecuador South America| Loja Ecuador South America| Morona-Santiago Ecuador South America| Pichincha Ecuador South America| Zamora-Chinchipe Ecuador South America| Peru South America| Amazonas Peru South America| Cajamarca Peru South America| Cusco Peru South America| Pasco Peru South America| San Martín Peru South America| Brazil South America| Minas Gerais Brazil South America| São Paulo Brazil South America| Bolivia South America| Cochabamba Bolivia South America| La Paz Bolivia South America|