Linum L.

Linum is a genus of ca. 230 species, mainly distributed in the temperate regions of the world (Mabberley 2008). Three species are native in Belgium: Linum catharticum L., L. leonii F.W. Schultz and L. tenuifolium L. (Lambinon & Verloove 2012), all confined to dry and sunny, calcareous habitats. In Belgium L. leonii is a very rare species, only known at present from two localities close to the French borders (Viroin). Ockendon & Walters (1968) only cited it from Germany and France. Several species of Linum are cultivated, especially L. usitatissimum (flax, linseed). It is mainly grown (also in Belgium) for fiber and as an oilseed crop. Several other species are cultivated as ornamentals (see for instance Upson 1997 and Jäger & al. 2008 for useful accounts of the genus in Europe). Some are also included in wild flower seed mixtures (mainly Linum austriacum but also native L. tenuifolium). The latter, for instance, occurs on a coal mining spoil heap in Zolder-Koersel (at least since 2007), outside of its native distribution range, probably as a result of sowing.

Linum, as traditionally circumscribed, is paraphyletic. Radiola (and some other related genera) should either be included in Linum or Linum further divided (McDill 2009a,b, Repplinger 2009). Pending further studies it is here treated in its traditional sense (see also Tison & de Foucault 2014).

1       All leaves opposite. Petals white with yellow base, 4-6 mm long (at most twice as long as the sepals). Annual (native) === Linum catharticum

         Middle and upper cauline leaves alternate. Petals bluish, reddish, pinkish (rarely white), longer. Perennial or annual === 2

2       Annual === 3

         Perennial === 4

3       Petals usually dark red (more rarely paler). Flowers 30-40 mm across === Linum grandiflorum

         Petals bluish (rarely white). Flowers ca. 15 mm across === L. usitatissimum

4       Sepals with glandular margins. Petals pink (native) === L. tenuifolium

         Sepals with eglandular margins. Petals blue === 5

5       Flowers homostylous (stamens and stigma ca. at same height). Inflorescence relatively few-flowered (1-6 flowers). Capsule ca. 5-7 mm across. Stem slender, +/- decumbent, 5-15(-30) cm tall (native) === L. leonii

         Flowers heterostylous. Inflorescence often with more than 6 flowers. Capsule ca. 3,5-5 mm across. Stem more robust and erect, up to 60 cm tall === L. austriacum


Jäger E.J., Ebel F., Hanelt P. & Müller G. (eds.) (2008) Rothmaler Band 5. Exkursionsflora von Deutschland. Krautige Zier- und Nutzpflanzen. Springer Verlag, Berlin: 880 p.

Lambinon J. & Verloove F. (avec coll. Delvosalle L., Toussaint B., Geerinck D., Hoste I., Van Rossum F., Cornier B., Schumacker R., Vanderpoorten A. & Vannerom H.) (2012) Nouvelle Flore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des Régions voisines (Ptéridophytes et Spermatophytes). Sixième édition. Jardin botanique national de Belgique, Meise: CXXXIX + 1195 p.

Mabberley D.J. (2008) Mabberley’s plant-book (3th ed.). Cambridge University Press, Cambridge: XVIII + 1021 p.

McDill J.R. (2009a) Molecular phylogenetic studies in the Linaceae and Linum, with implications for their systematics and historical biogeography. PhD Dissertation Texas University. Available online at:

McDill J.R. (2009b) The Phylogeny of Linum and Linaceae Subfamily Linoideae, with Implications for Their Systematics, Biogeography, and Evolution of Heterostyly Syst. Bot. 34(2): 386-405. [available online at:]

Ockendon D.J. & Walters S.M. (1968) Linum. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 2. Cambridge University Press, Cambridge: 206-211.

Repplinger M. (2009) Phylogenie und Biogeographie der Linoideae (Linaceae). Evolution von Heterostylie / Homostylie in Linum. PhD dissertation University of Mainz. Available online at:

Tison J.-M. & de Foucault B. (coord.) (2014) Flora Gallica. Flore de France. Editions Biotope, Mèze : xx + 1196 p.

Upson T. (1997) Linum. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 5. Cambridge University Press, Cambridge: 71-73.

Taxonomic name: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith