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 Key to Linum species in Mexico 1. Fruit dehiscent into 5 segments ..........................................................................................................................................................2 - Fruit dehiscent into 10 segments ........................................................................................................................................................8 2. Corolla yellow ....................................................................................................................................................................................3 - Corolla yellow-orange to salmon with a red to wine-red base...........................................................................................................5 3. Root thin; stem puberulent at the base; fruit ovoid ............................................................................................................................4 -. Root thick; stem glabrous; fruit ellipsoid ........................................................................................................................ L. aristatum 4. Stipular glands absent, sometimes present only in some parts, then barely conspicuous.................................................. L. australe - Stipular glands present throughout the plant, very conspicuous .......................................................... L. australe var. glandulosum 5. Stems pilose locally or throughout .....................................................................................................................................................6 -. Stems glabrous throughout .................................................................................................................................................................7 6. Plant hirsutulose at the base; sepals glabrous; fruit with translucent thin pericarp............................... L. berlandieri var. filifolium - Plant densely gray-puberulent to the inflorescence; sepals pubescent; fruit with thick opaque pericarp ..................... L. puberulum 7. Basal leaves alternate; sepals deciduous, 3-nerved; anthers brick-red........................................................................... L. elongatum -. Basal leaves opposite; sepals persistent, 1-nerved; anthers brown ..................................................................................... L. vernale 8. Corolla blue ........................................................................................................................................................................................9 - Corolla yellow, yellow-orange, white, or pink .................................................................................................................................11 9. Stems erect or ascending ..................................................................................................................................................................10 - Stems creeping or prostrate ............................................................................................................................................ L. rzedowskii 10. Pedicels villous; anthers white; stigmata capitate ................................................................................................................. L. lewisii - Pedicels glabrous; anthers bright-yellow; stigmata linear to claviform ................................................................... L. usitatissimum 11. Plants densely pubescent throughout................................................................................................................................................12 - Plants glabrous or locally pubescent ................................................................................................................................................13 12. Basal leaves opposite; bracts with stipular glands, conspicuous; petals yellow-orange, pilose at the base.................. L. scabrellum - Basal leaves in whorls; upper bracts without stipular glands; petals yellow, glabrous..................................................... L. tenellum 13. Stems decumbent..............................................................................................................................................................................14 - Stems erect........................................................................................................................................................................................15 14. Leaves widely ovate or elliptical, scariose; anthers 0.7–1.2 mm long............................................................................... L. cruciata - Leaves narrowly oblanceolate, obovate to narrowly elliptical, rough; anthers 0.5 mm long...................................... L. lasiocarpum 15. Annual herbs.....................................................................................................................................................................................16 - Perennial herbs .................................................................................................................................................................................17 16. Basal leaves in whorls, obovate; 3-nerved sepals; styles fused to near the apex; fruit pale-yellow throughout............... L. longipes - Basal leaves opposite, elliptical-oblanceolate; 1-nerved sepals; styles free; fruit yellow with purple hues on the upper portion ...... ................................................................................................................................................................................ L. neomexicanum 17. Root thick .........................................................................................................................................................................................18 - Root thin ...........................................................................................................................................................................................20 18. Basal leaves opposite or in whorls; stigmata light brown; fruit yellow with purple hues at the upper portion ...............................19 - Basal leaves alternate; stigmata yellow; fruit yellow throughout ................................................................................... L. flagellare 19. Styles free or connate at the base ...................................................................................................................................... L. orizabae - Styles fused to half or close to the apex ....................................................................................................................... L. mexicanum 20. Fruit glabrous....................................................................................................................................................................................21 - Fruit pubescent at the apex ................................................................................................................................................. L. nelsonii 21. Fruit yellow with purple hues at the upper portion; petals white or pink........................................................................... L. pringlei - Fruit yellow throughout; petals yellow to greenish-yellow..............................................................................................................22 22. Basal leaves alternate or opposite....................................................................................................................................... L. rupestre - Basal leaves in whorls ......................................................................................................................................................................23 23. Leaves with stipular glands at the base; pedicels 0.1–0.2 mm long; bracts 2.0–3.0 mm long; sepals 2.0–5.0 × 1.0– 1.5 mm , seeds reddish-brown............................................................................................................................................................ L. schiedeanum - Leaves without stipular glands at the base; pedicels 3.5–14.7 mm long; bracts 0.6–1.1 mm long; sepals (1.2)1.7–1.8 × 0.5–0.7 mm ; seeds light brown.................................................................................................................................................... L. modestum