Linum lasiocarpum Rose (1909: 274)

González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, Phytotaxa 549 (2), pp. 141-184 : 154-155

Linum lasiocarpum Rose (1909: 274) . ( Fig. 6c ).

Type:— MEXICO. Nuevo Leon, near Monterrey, Pringle 10209 (holotype US!, isotypes CM, F, GH!, MICH, MO, MSC, NY!, UC!) .

Description: — Herbs, annual, 15–40 cm in height, glabrous, root thin; stems slightly decumbent, extending toward the inflorescence, branched from the base, glabrous. Leaves entire, basal leaves arranged in whorls of 4, narrowly oblanceolate to obovate; distal leaves opposite and alternate, narrowly elliptical; (4.0)6.0–23.0 × 1.7–6.8 mm, subsessile, apex obtuse; 1-nerved, nervation more evident in the abaxial surface; occasionally rough hairs near leaf nodes and bases, prominent stipular glands present at the base. Inflorescence a cymose panicle, branched, occupying more than half the plant height; pedicels 0.8–2.1 mm long, villous; bracts 2.2–4.1 mm long, margin glandular-dentate, apex acute, prominent stipular glands present at the base; sepals persistent, lanceolate, 1.7–2.5 × 0.5–1.0 mm, marginal glands conspicuous, sessile, apex acute to acuminate, 3-nerved, stipular glands present; petals yellow, narrowly obovate, 3.0– 4.0 mm long, glabrous; stamens 2.0–3.0 mm long; anthers 0.5 mm long, light yellow; staminodia minute; styles free, 2.0 mm in length; stigmata capitate, light yellow. Fruit widely ovoid, yellow, 1.2–2.1 × 1.3–2.0 mm, sparsely hirsute at the mid portion, pericarp thin, apex acute, dehiscent into 10 segments, false septa poorly developed, true septa with some marginal hairs; seeds ovate, light brown, 0.9-1.2 × 0.6-0.7 mm.

Distribution: —Endemic to Mexico, in Coahuila, Nuevo Leon, and Tamaulipas ( Fig. 5a ).

Habitat and ecology: —Oak forests, oak-pine forests, grasslands. Elevation 600–2100 m. Kastanozem, Phaeozem, Lithosol, Vertisol, and Xerosol soil types.

Phenology:—Flowering and fruiting in March–June.

Note: —Although the prominent stipular glands at the base of leaves and bracts and the villous pedicels clearly separate L. lasiocarpum from other northern species such as L. aristatum , L. berlandieri var. filifolium , L. elongatum , L. flagellare , L. modestum , L. puberulum , this is not the case with its closest species, L. nelsonii . However, the nerves on the leaf under surface, the marginal glands of sepals, and the pointed and hirsute fruits, together allow clearly separating L. lasiocarpum from L. nelsonii .

Conservation status: —According to the criteria established by the IUCN (2019) L. lasiocarpum is EN (B1 + 2ac(iii)), with an EOO <20,000 km 2 (2,369.840 km 2) and AOO of 28 km 2. The species is restricted to a few states in the Northeast of Mexico.

Specimens examined: — MEXICO. Coahuila: Castaños, Sierra La Gavia , 1351 m, 26°19’60”N, 101°15’00”W, 12 May 1992, M.H. Mayfield et al. 1321 ( TEX!) . Nuevo Leon: Galeana , 6 km E of Potosí, 2100 m, 3 July 1984, Hinton et al. 18725 ( CHAPA!) ; Montemorelos, El Pastor, 845 m, 19 May 1994, Hinton et al. 24232 (ANSM!, CIIDIR!, IEB!, MEXU!) ; Monterrey, Northwestern outskirts of Monterrey , 29 March 1973, C.M. Rogers 13455 ( MEXU!) ; Monterrey, Foothills of the Sierra Madre , 610 m, 15 April 1906, C.G. Pringle 10209 ( MEXU!) ; Santiago, La Nogalera, 950 m, 16 June 1994, Hinton et al. 24409 (ANSM!, IEB!) ; Santiago, Cola de Caballo , 800 m, 25°23’00”N, 100°10’00”W, 20 June 1984, J.A. Villarreal & M.A Carranza 2778 ( ANSM!) ; Santiago , El Manzano, 1600 m, 19 May 2004, E. Estrada et al. 16139 ( ANSM!) . Tamaulipas: San Carlos, Sierra de San Carlos , 1134 m, 24°31’00”N, 98°57’01”W, 17 June/ 1987, G. Nesom et al. 6053 ( TEX!) .

Figures

FIGURE 5. Geographic distribution in the Mexican territory of:A. L. cruciata, L. lasiocarpum, L. lewisii, L. mexicanum, and L. tenellum; B. L. elongatum, L. neomexicanum, L. puberulum, L. rzedowskii, and L. schiedeanum; C. L. modestum, L. orizabae, L. pringlei, L. scabrellum, and L. vernale. Maps by Ma. Isabel Olivares.

FIGURE 6. A. Linum elongatum; B. Linum flagellare; C. Linum lasiocarpum; D. Linum lewisii. Photographs by José Luis Colin.