Taxonomic update of the flax family in Mexico Author González-Velasco, Juan 0000-0001-8743-3906 Departamento de Botánica, Colegio de Postgraduados. km 36.5 carretera México-Texcoco, Montecillo, 56230 Texcoco, Mexico, Mexico. & gonzalez. juan @ colpos. mx; https: // orcid. org / 0000 - 0001 - 8743 - 3906 gonzalez.juan@colpos.mx Author Burgos-Hernández, Mireya 0000-0003-3036-297X Departamento de Botánica, Colegio de Postgraduados. km 36.5 carretera México-Texcoco, Montecillo, 56230 Texcoco, Mexico, Mexico. & burgos. mireya @ colpos. mx; https: // orcid. org / 0000 - 0003 - 3036 - 297 X burgos.mireya@colpos.mx Author Galván-Escobedo, Iris G. 0000-0003-4250-4971 Departamento de Botánica, Colegio de Postgraduados. km 36.5 carretera México-Texcoco, Montecillo, 56230 Texcoco, Mexico, Mexico. & igalvan @ colpos. mx; https: // orcid. org / 0000 - 0003 - 4250 - 4971 igalvan@colpos.mx Author Castillo-Campos, Gonzalo 0000-0002-3059-8109 Red de Biodiversidad y Sistemática. Instituto de Ecología A. C. Carretera antigua a Coatepec km. 351, El Haya, 91073, Xalapa, Veracruz, Mexico. & gonzalo. castillo @ inecol. mx; https: // orcid. org / 0000 - 0002 - 3059 - 8109 gonzalo.castillo@inecol.mx text Phytotaxa 2022 2022-06-08 549 2 141 184 journal article 67684 10.11646/phytotaxa.549.2.3 62e44cf6-6f9d-4658-a89b-a0ddf687b5b9 1179-3163 6622753 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 !) .