Juncus marginatus Rostk.

Authority

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

Family

Juncaceae

Scientific Name

Juncus marginatus Rostk.

Type

Type. U.S.A. Pennsylvania (lectotype, B-W 6861! sheet 1, here selected; sheet 1, marked  Mühlenberg W in the lower right corner, agrees with Rostkov s illustration in the protologue).

Synonyms

Juncus triglumis L., Juncus aristulatus Michx., Juncus aristatus Larrañaga, Juncus marginatus var. aristulatus (Michx.) Coville, Luzula juncoides Poir., Juncus biflorus Elliott, Juncus marginatus var. biflorus Chapm., Juncus marginatus var. odoratus Torr., Juncus odoratus (Torr.) Steud., Juncus triandrus Gouan, Juncus heteranthos Nutt., Juncus cylindricus M.A.Curtis, Juncus canaliculatus Liebm., Juncus marginatus var. vulgaris Engelm., Juncus marginatus var. paucicapitatus Engelm., Juncus marginatus var. setosus Coville, Juncus setosus (Coville) Small, Juncus buchenavi Sved., Juncus aristulatus var. pinetorum Coville, Juncus longii Fernald

Description

Species Description - Perennial, cespitose herbs, 40-100 cm tall. Rhizome short, densely branching, 2-4 mm diam. Culms sometimes bulbous at the base, erect, slightly compressed, 0.5-3 mm diam., smooth. Cataphylls absent. Foliar leaves basal and cauline; basal leaves 2-5 to each culm, sheaths to 9 cm long with the margins terminating in two 0.5-1 (-3) mm long, rounded auricles; blade 10-30 x 0.1-0.5 cm, flat, usually with 1 abaxial and 2 adaxial nerves clearly visible, but otherwise without macroscopical bifacial differentiation; cauline leaves spaced along the culm, similar to basal leaves but distal ones shorter. Inflorescence compound, anthelate, 4-15 x 2-10 cm, principal branches to 10 cm long and 1 mm diam., distal branches shorter, the ultimate ones ca. 0.3 mm diam., flower heads (5-)10-40(-60), 5-7 mm diam., 3-5(-10)-flowered, stramineous to dark brown. Lower inflorescence bract resembling a cauline leaf, as long as or shorter than the inflorescence, distal bracts shorter, floral bracts lanceolate, acute, scariose, as long as or shorter than the flowers, bracteoles absent. Tepals unequal, outer tepals the shortest, 2-2.8(-3) mm long, lanceolate, apically obtuse to acute or sometimes short awned, concave, scariose towards the margin, inner tepals the longest, 2.4-3 mm long, lanceolate, apically obtuse to acute, with scariose margin inflexed to form a little cap when young, flat. Stamens 3, 1.2-2.2(-3) mm long; filaments linear, somewhat flattened; anthers oblong, 0.4-l(-1.5) mm long, usually obviously shorter than the filaments but occasionally as long, dark castaneous, robust in appearance, often protruding between the tepals after anthesis. Style ca. 0.1 mm long. Stigmas 0.5-1 mm long. Capsule about as long as the tepals, broadly ellipsoid, apiculate, round in x.s., 2-2.5 x 1.8-2 mm, dark brown with glossy surface, 3-septate, dehiscing apically, the valves becoming inflexed. Seeds narrowly and obliquely ellipsoid, apiculate, 0.5-0.6 x 0.15-0.2 mm, with longitudinal ribs and transverse ribs, yellow-brown.

Discussion

Engelmann (1866) divided J. marginatus into three varieties based on the number of flower heads and the number of flowers in each head. Coville (1893) added characters of the seeds and also divided this species into three varieties, although they were differently circumscribed than were those of Engelmann. Small (1903) raised Coville’s varieties to species rank, but recent North American floras have mostly accepted two species, J. biflorus and J. marginatus. Juncus biflorus is said to have many 2-3 flowered heads, and J. marginatus is said to have few 5-12 flowered heads in the inflorescence; J. marginatus var. marginatus is said to have brown capsules and obtuse or acute tepals, and J. marginatus var. setosus is said to have glossy capsules and aristate inner tepals. The distinction between these taxa is particularly difficult in the southern United States, where some treatments have lumped them (e.g., Godfrey & Wooten, 1979), whereas some recent treatments from the northern United States (e.g., Clemants, 1990) keep them apart. I have not been able to arrange the neotropical and temperate South American material of J. marginatus in recognisable subspecific taxa.

Distribution and Ecology: Juncus marginatus is widely distributed in E North America from Nova Scotia to Florida and Arizona. In Central America it occurs in the highlands from Mexico to Costa Rica, and in the West Indies on Bermuda and W Cuba. In South America there are a few collections from Venezuela, and it is common in SE Brazil, Uruguay, Argentina, and Paraguay. It is found at low elevations in temperate areas, but in Central America and Venezuela it was collected at elevations of 800-2000 m. It grows in wet places along ditches and streams.

Distribution

Mexico North America| Chiapas Mexico North America| Durango Mexico North America| Jalisco Mexico North America| México Mexico North America| Oaxaca Mexico North America| San Luis Potosí Mexico North America| Veracruz Mexico North America| Guatemala Central America| Alta Verapaz Guatemala Central America| Huehuetenango Guatemala Central America| Jalapa Guatemala Central America| Quiché Guatemala Central America| Sololá Guatemala Central America| Zacapa Guatemala Central America| Belize Central America| Cayo Belize Central America| Honduras Central America| Comayagua Honduras Central America| El Paraíso Honduras Central America| Intibucá Honduras Central America| La Paz Honduras Central America| Morazán Honduras Central America| Nicaragua Central America| Nueva Segovia Nicaragua Central America| Jinotega Nicaragua Central America| Costa Rica South America| Guanacaste Costa Rica Central America| Cuba South America| Isla de Piños Cuba South America| Las Villas Cuba West Indies| Piñar del Río Cuba South America| Villa Clara Cuba South America| Venezuela South America| Anzoátegui Venezuela South America| Sucre Venezuela South America| Paraguay South America| Caaguazú Paraguay South America| Paraguarí Paraguay South America|