Linum usitatissimum Linnaeus (1753: 277)

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 : 175-176

Linum usitatissimum Linnaeus (1753: 277) . ( Fig. 10d ).

Type:—Habitat hodie inter segetes, Europae australis. Herb. Clifford 114, Linum no. 1. (lectotype BM!).

Linum angustifolium Hudson (1778: 134) .

Linum humile Miller (1768: 2) .

Description:— Herbs, annual, 20–100 cm in height, glabrous, root thick; stems erect, smooth to simple striate, sometimes sparsely branched from the base, cylindrical, glabrous. Leaves entire, alternate, linear to linear-lanceolate, 10.0–40.0 × 0.7–3.0(4.0) mm, sessile, apex acute to acuminate, 1-nerved, scariose, glabrous, stipular glands absent. Inflorescence an open cymose panicle, glabrous; pedicels glabrous, 20-35 mm long; bracts 10.0–24.0 mm long, glabrous, margin entire, apex acute, stipular glands absent; sepals persistent, elliptical to ovate, 5–8 mm long, margin entire, thoroughly ciliated toward the apex or finely ciliate-fimbriate, scariose, apex acuminate, 1-nerved, stipular glands absent; petals blue, obovate, 9–15 mm long, glabrous; stamens 4.0–5.0(7.0) mm long; anthers (1.0)1.8–2.0 mm long, bright-yellow; staminodia absent; styles free or connate at the base, 3.0–6.0 mm long; stigmata linear or claviform, white. Fruit widely ovate to subglobose, yellow, 6–10 × 5–10 mm, glabrous, pericarp thick, apex rounded, dehiscent into 10 segments; false septa ciliated; seeds lanceolate, brown, 4.0–6.0 × 2.5–3.0 mm.

Distribution: —Native of Europe and Asia ( India, Eastern Mediterranean and Near East). Introduced in America, in Canada, United States of America; in Mexico, in Coahuila, State of Mexico, Jalisco, Michoacan, Nuevo Leon, and Sonora ( Fig. 2b ); to South America; in Asia (far East), South Africa, and Australia.

Habitat and ecology: —Ruderal and cropland. Elevation 1900–3000 m. Limestone Andosol, Cambisol, Phaeozem, Planosol, Regosol, and Vertisol soil types.

Phenology: —Flowering and fruiting throughout the year.

Note: —This blue-flowered species can easily be confused with L. lewisii ; however, the size of the plant, leaves, and fruits are larger in L. usitatissimum . Besides, the linear to claviform styles, as well as its habitat, are key characters for differentiating the species.

Conservation status: — Linum usitatissimum is the only species of the family in Mexico that is introduced and naturalized. It is considered a crop, ruderal and weed species ( Martínez-Orea et al. 2020).

Specimens examined: — MEXICO. Coahuila: Saltillo, Invernadero UAAAN Buenavista , 1750 m, 25°21’25”N, 101°02’04”W, 13 May 1986, L. Arce 288 ( ANSM!) . State of Mexico: Texcoco , 2240 m, 19°29’28”N, 98°52’47”W, 14 August 1976, S.D. Koch 76151 ( CHAPA!) ; Texcoco, Campo Experimental Chapingo , 2250 m, 19°29’00”N, 98°53’00”W, 11 October 1984, G. Vázquez C. 33 ( CHAPA!) ; Villa Guerrero, Entre el Pueblo y la Autopista, 2267 m, 18°59’20.3”N, 98°38’53.9”W, 6 October 2000, H. Vibrans 6781 ( CHAPA!) . Jalisco: Chapala, Carretera Ocotlán-Atequiza , 1500 m, 20°19’38”N 103°11’08”W, 20 May 1968, L.M.V. de Puga 2727 ( IBUG!) ; Ocotlán , 20°20’45”N, 102°46’12”W, 1 April 1973, J. Fdo. Amador A. 25 ( IBUG!) ; Tepatitlán , 20°48’26”N, 102°46’07”W, 1 December 1977, T. Tejeda 135146 ( IBUG!) ; Zapopan, Villa Universitaria al W de Guadalajara, 1550 m, 20°41’47”N, 103°24’47”W, 15 March 1975, L.M.V. de Puga 17066 ( IBUG!) . Michoacan: Pátzcuaro, Salida a Uruapan , 2100 m, 19°29’36”N, 101°36’00”W, 20 September 1993, J.M. Escobedo 2649 ( IEB!) . Nuevo Leon: Galena, Cerro el Potosí cerca de San José de la Joya, 3200 m, 24°53’12.8”N, 100°14’28.6”W, 24 September 2011, E. Estrada et al. 20955 ( ANSM!) . Sonora: Cajeme, Distrito Guaymas , 28°05’26”N, 110°00’47”W, 18 May 1957, J. Corral 44 ( CHAPA!) .

Figures

FIGURE 2. Geographic distribution in the Mexican territory of: A. H. micranthum, L. aristatum, L. berlandieri var. filifolium, L. longipes, and L. rupestre; B. L. australe, L. australe var. glandulosum, L. flagellare, L. nelsonii, and L. usitatissimum. Maps by Ma. Isabel Olivares.

FIGURE 10. A. Linum rzedowskii; B. Linum schiedeanum; C. Linum tenellum; D. Linum usitatissimum. Photographs by José Luis Colin.