Linum modestum C.M. Rogers (1964c: 406)

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 : 159-160

Linum modestum C.M. Rogers (1964c: 406) . ( Fig. 8 ).

Type:— MEXICO. Nuevo Leon : Pablillo, south of Galeana , side of arroyo, 1900–2000 m, Pennell 16976 (holotype US!, isotype PH!) .

Description: — Herbs, perennial, 15–20 cm in height, glabrous, root thin; stems erect ascending, dark-purple, striate, branched from the base, glabrous. Leaves, basal ones entire, arranged in whorls of 4; distal ones glandular-dentate, alternate; 0.7–4.3 × 0.3–2.3 mm, lanceolate, sessile, apex acute, 1-nerved, glabrous, rough, stipular glands absent. Inflorescence a panicle with thin branches, ascending, pedicels 3.5–14.7 mm long; bracts 0.6–1.1 mm long, margin glandular-dentate, apex rounded, stipular glands absent; sepals persistent, lanceolate to ovate, (1.2)1.7–1.8 × 0.5–0.7 mm, margin glandular-dentate, apex mucronate to subacute, 1-nerved, stipular glands absent; petals yellow-green, oblanceolate, 3.0– 3.5 mm long, glabrous; stamens 2.0 mm long; anthers 0.4–0.6 mm long, light yellow; staminodia minute or absent; styles free, 1.6–1.7 mm long; stigmata capitate, light yellow. Fruit widely ovoid, yellow, (0.9)1.5–1.6 × 1.1–1.5(1.7) mm, glabrous, pericarp thin, apex acute, dehiscent into 10 segments; false septa incomplete, true septa sparsely ciliate; seeds ovate to elliptical, light brown, 0.8 × 0.5 mm.

Distribution: —Endemic to Mexico, in Nuevo Leon ( Fig. 5c ).

Habitat and ecology: —Cypress-juniper forest, crassi-rosette-leaved thorny shrublands, pine forests. Elevation 1200–2300 m. Phaeozem, Lithosol, Regosol, Solonchak, and Xerosol soil types.

Phenology: —Flowering in March–September; fruiting in July–November.

Note: —The dark-purple striate stems, branched inflorescence, minute leaves and floral parts, and acute fruit, together with the narrow strip of gypsum soils where it thrives, make it one of the most unique species of the genus Linum in Mexico.

Conservation status: —According to IUCN Red List Categories and Criteria ( IUCN 2019), L. modestum is EN (B1 + 2ab(iii)). Its EOO is 803.899 km 2 and AOO is 40 km 2. In addition, this species is not only an endemic to Mexico, but also presents a type of edaphic endemism ( Nesom 1983), so its distribution is restricted to a small area of the state of Nuevo Leon. Moreover, mining operations and human settlements are recorded in its distribution range ( Toledo 2005, Salinas-Rodríguez 2015, Gutiérrez-García & Ricker 2019), which may exert pressure on the viability of its populations.

Specimens examined: — MEXICO. Nuevo Leon: Galeana, Santa Rita , 2120 m, 25 June 1981, Hinton et al. 18196 (ANSM!, CIIDIR!, ENCB!, IEB!) ; Galeana, Santa Rita , 2010 m, 14 May 1981, Hinton et al. 18240 (ANSM!, ENCB!) ; Galeana , SW of Laguna de Labradores, 2267 m, 17 October 2003, Hinton et al. 28034 ( ANSM!) ; Galeana, Santa Rita , 2160 m, 12 January 1989, Hinton et al. 19293 ( CIIDIR!) ; Galeana, 700 m al NW del Rancho de Los aguacates, 2250 m, 08 October 1976, L. Lezama de la R., s.n. ( INEGI!) ; Galeana, 12.2 road miles E of San Roberto Jct. on road to Galeana , 2150 m, 24°40’00”N, 100°09’00”W, 16 September 1980, J. Henrickson & P. Bekey 18517 ( MEXU!) ; Galeana, Just S of Cerro Potosí, 2100 m, 24°46’00”N, 100°13’00”W, 10 October 1982, J. Henrickson & W. Hess 19265 ( MEXU!) ; Galeana , 3.2 mi S of Galeana, 24°47’00”N, 100°03’00”W, 10 October 1985, B.L. Turner et al. 15553 ( XAL!) ; Rayones, Galeana-Rayones + 18 km, 1270 m, 27 February 1990, Hinton et al. 20155 (CHAP!, CHAPA!) ; Rayones, Lomas Blancas in San Pedro Carrizales , 1204 m, 12 September 2008, Hinton et al. 28708 ( ANSM!) ; Rayones , Sierra Pelillos , Puerto Mesa de León, 2100 m, 25°00’00”N, 100°16’00”W, 7 June 1988, J.A. Villarreal et al. 4359 ( ANSM!) .

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 8. Linum modestum.A.Aspect general of the plant; B. Basal leaves; C. Distal leaves; D. Flower; E. Filament and anther; F Styles and stigmata; G. Fruit. Illustrated by Lizbeth Pérez Lucas, based on Henrickson 19265.