1. Linaceae DC. ex Perleb

    1. This family is accepted.


Linaceae, Hutchinson and Dalziel. Flora of West Tropical Africa 1:2. 1958

Trees, shrubs, rarely herbs; branches sometimes climbing by hooks
Leaves simple, alternate or opposite; stipules present or absent, sometimes gland-like
Flowers actinomorphic, hermaphrodite
Sepals 4–5, free or partly united, imbricate
Petals free, contorted, fugacious
Stamens as many as and alternate with the petals, sometimes alternating with small staminodes; filaments connate at base; anthers introrse, 2-celled, opening lengthwise
Ovary superior, 3–5-celled, cells often again partially subdivided; ovules 2 in each cell, pendulous; styles 3–5, free or partly united, with simple capitate stigmas
Fruit a septicidal capsule
Seeds compressed, shining, with or without endosperm; embryo straight, cotyledons flat

Linaceae, Doreen L. Smith. Flora of Tropical East Africa. 1966

Trees, shrubs, lianes or herbs
Leaves simple, alternate or opposite; stipules present, rarely absent, divided, entire or gland-like
Inflorescence a terminal or axillary cyme, rarely flowers solitary
Flowers regular, hermaphrodite, hypogynous
Sepals 4–5, imbricate, free or partially united
Petals 4–5, contorted in bud, free or partially united at base, often clawed
Stamens 1–3 times as many as sepals; filaments united at base; staminodes sometimes present
Ovules pendulous, 2 per loculus Ovary superior, 2–5-locular; each loculus often subdivided by a false septum Styles 2–5, free or united at base
Fruit a capsule or drupe
Seeds with or without endosperm; embryo straight or slightly curved

Secco, R. de S. (2012). Neotropical Linaceae.


Annual or perennial herbs, shrubs or trees.  Leaves simple , alternate or opposite, petiolate or sessile , with deciduous stipules or exstipulate , these sometimes modified into glands Inflorescences racemes, panicles, terminal spikes or axillary fascicles.  Flowers bisexual , actinomorphic ; sepals 4-5, free or partially fused at base, imbricate ; petals 5, free , irregular, with or without appendages at base; stamens 5-15, iso- or diplostemonous, with filaments fused at base, anthers longitudinally dehiscent , introrse; staminodes sometimes present; ovary superior , 2-5-locular, ovules (1-)2 per locule , style 1-3-5-fid, free or forming a column, stigma sometimes capitate Fruit drupaceous , indehiscent or septicidal capsule Seeds alate or not, endosperm abundant, scarce or absent, embryo straight with flattened cotyledons.

General Description
Notes on delimitation
  • The position of Linaceae in the Malphigiales clade is still controversial as are the relationships among the genera considered part of the Hugoniaceae and the Linaceae s.s.  According to Cronquist (1988), the neotropical genera Hebepetalum Benth. and Roucheria Planch. should be included in the Hugoniaceae, while the APG II (2003), APG III (2009), McDill & Simpson (2011) place these two genera in the Linaceae subfamily Hugoniaceae together with three Old World genera.
  • Ochthocosmus Benth. (seven species) and Cyrillopsis Kuhlm. (two species) traditionally belonged to the Linaceae, but according to Ramirez & Berry (1999), Ramirez & Secco (2008), and APG III (2009) they are currently placed in Ixonanthaceae.
  • In the Neotropics Linaceae consists of native (Hebepetalum, Roucheria and Linum), endemic (Linum, Hebepetalum and Roucheria), and cultivated (Linum and Cliococca) species.
General notes
  • Amongst Linaceae, Linumusitatissimum L. is the species of greatest economic interest, as a source of fibre from the stem (linen), for medicinal uses and as a food source (linseed, and flax oil and seed).
  • Record & Hesse (1949) mentioned that the woods of Hebepetalum and Roucheria are hard and heavy, and therefore are probably not significantly attacked by insects, and are of good durability.
Number of genera

Linaceae comprises four genera in the Neotropics:

  • Cliococca Bab. - 1 spp.,
  • Hebepetalum Benth. - 3 spp.,
  • Linum L. (ca. 187 species in total, c. 45 in the New World tropics and subtropics).
  • Roucheria Planch. - 7 spp.
Distribution in the Neotropics
  • According to Ramirez & Berry (1999) and Secco (2008, 2010) three species of Hebepetalum, seven of Roucheria, six of Linum (some cultivated) and one of Cliococca occur in the Neotropics. 
  • Kearns (2004) cited ca. 45 species of Linum occuring throughout the New World tropics and subtropics.
  • Rogers (1968) recognised 14 species of Linum in Central America.
Distinguishing characters (always present)
  • Herbs (Linum and Cliococca), shrubs or trees (Hebepetalum and Roucheria).
  • Simple leaves, usually alternate, sometimes opposite (Linum).
  • Sepals and petals 5; stamens 5-15; ovarysuperior.
  • Fruits drupaceous (Hebepetalum and Roucheria) or septicidal capsules (Linum and Cliococca).
Other important characters
  • Oily seeds present in Linum.
Key differences from similar families

1.   Stamens up to 5, presence of intrastaminal disc; petals imbricate, persistent in fruit .. Ixonanthaceae 1.   Stamens 5-120; absence of intrastaminal disc; petals absent in fruit .. 2

2.   Absence of balsamic oils and resins in the bark and fruit; stamens up to 15; connective not thickened, anther thecae normal; absence of ovarydisc .. Linaceae2.   Presence of balsamic oils and resins in the bark and fruit; stamens 10-120; connective thickened, anther thecae minute; presence of ovarydisc .. Humiriaceae

Notable genera and distinguishing features
  • In the Neotropics the most notable genera are speceis of Hebepetalum and Roucheria, found as trees or shrubs most frequently in forests.  Roucheria is easily identified by its leaves with closely spaced, parallel venation, whereas Hebepetalum is distinguished by the leaves with typically reticulatevenation.
  • Cliococca and Linum are herbs, but the former has subterranean rhizomes and the latter does not. Moreover, Linum flowers are more showy with convolute yellow, blue or red petals, which are larger than the sepals.
Useful tips for generic identification

Key to the genera of Neotropical Linaceae

1.   Shrubs or trees; stamens 10 or more; fruit drupaceous —. 2 1.   Herbs; stamens 5; fruit a septicidalcapsule —. 3

2.   Leaf venation reticulate; flowers with densely barbate petals internally, base unguiculate —. Hebepetalum
2.   Leaf venation with numerous parallel secondary veins; flowers with glabrous petals internally, base not unguiculate —. Roucheria

3.   Plants with subterranean rhizomes; petals imbricate, white or pale pink, smaller than sepals; ovary with complete false septa; fruitindehiscent; mature seeds enclosed by carpels when released —. Cliococca
3.   Plants without subterranean rhizomes; petals convolute, yellow, blue or red, larger than sepals; ovary with incomplete false septa; fruit dehiscent; mature seeds free when released —. Linum

Important literature

APG II. 2003. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II. Botanical Journal of the Linnean Society 141: 399-436.

APG III. 2009. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III. Botanical Journal of the Linnean Society 161: 105-121.

Hooren, A.M.N. van & Nooteboom, H.P. 1984. Linaceae and Ctenolophonaceae of Malesia with notes on their demarcation and the relationships with Ixonanthaceae. Blumea 29: 547-563.

Kearns, C.A. 2004. Hugoniaceae, Linaceae.  In: Smith, N., Mori, S.A., Henderson, A., Stevenson, D.W. and Heald, S.V. (eds.). Flowering Plants of the Neotropics, pp. 184-185; 215-216. The New York Botanical Garden, Princeton University Press, Princeton.

Macbride, J.F. 1949. Linaceae. In: J.F. Macbride (ed.) Flora of Peru. Field Mus. Nat. Hist., Bot. ser. 13, part 3(2): 621-633.

McDill, J. & Simpson, B.B. 2011. Molecular phylogenetics of Linaceae with complete generic sampling and data from two plastid genes. Bot. J. Linnean Soc. 165: 64-83.

Mildner, R.A. & Rogers, C.M. 1978. Revision of the native South American species of Linum (Linaceae). Phytologia 39: 343-390.

Ramirez, N., Berry, P.E. & Jardim, A. 1999. Hugoniaceae, Ixonanthaceae. In: Steyermark, J.A., Berry, P.E., Yatskivych, K. and Holst, B.K. (eds.), Flora of the Venezuelan Guayana, vol. 5, pp. 618-623; 664-671. Missouri Botanical Garden Press, St. Louis.

Ramirez, N. & Secco, R.S. 2008. Hugoniaceae, Ixonathaceae. In: Hokche, O., Berry, P.E. & Huber, O. (Eds). Nuevo Catálogo de la Flora Vascular de Venezuela, pp. 418-419; 422-423. Fundación Instituto Botánico de Venezuela.  Dr. Tobias Lasser, Caracas.

Record, S.J. & Hesse, R.W. 1949. Timbers of the New World. New Haven, Yale University, 640 pp.

Rogers, C.M. 1968. Yellow-flowered species of Linum in Central America and Western North America. Brittonia 20 (2): 107-135.

Rogers, C.N. & Smith, L.B. 1975. Lináceas. In: Reitz, R. (ed.), Flora Ilustrada Catarinense. fasc. LINA: 3-34. Herbário Barbosa Rodrigues, Itajaí, Santa Catarina.

Secco, R.S. 2008. Linaceae. In: Hokche, O., Berry, P.E. & Huber, O. (Eds). Nuevo Catálogo de la Flora Vascular de Venezuela, p. 670. Fundación Instituto Botánico de Venezuela.  Dr. Tobias Lasser, Caracas.

Secco, R.S. & S.M.B. Silva. 1990. Materiaes para  a Flora Amazônica- VIII. Contribuição à sistemática de Linaceae da Amazônia Brasileira. Bol. Mus. Para. Emilio Goeldi, série Botânica 6(1): 113-135.

Sothers, C.A.; J.M. Brito & R.S. Secco. 1999. Hugoniaceae. In Ribeiro, J.E.L. et al. (editors), Flora da Reserva Ducke. Manaus, INPA/DFID. p. 504.

Steyermark, J.A. & J.L. Luteyn. 1980. Revision of the genus Ochthocosmus (Linaceae). Brittonia 32 (2): 128-143.


Linaceae, N. K. B. Robson. Flora Zambesiaca 2:1. 1963

Trees, shrubs, lianes or herbs, often with tendrils on climbing shoots, glabrous or with an indumentum of simple hairs
Leaves alternate or opposite, simple, penninerved or 1-nerved; stipules divided or entire or gland-like, deciduous (rarely absent)
Flowers in terminal or axillary cymes (or rarely solitary), actinomorphic, bisexual, usually heterostylic
Sepals (4) 5, imbricate, free or partially united
Petals (4) 5, contorted in bud, free or very rarely united at the base, often unguiculate, fugacious
Stamens twice (rarely three times) as many as the petals, or with the antipetalous whorl staminodial or absent; filaments ± united in the lower part, sometimes glandular at the base; anthers introrse, dorsifixed, dehiscing longitudinally
Ovary superior, with 2–5 2-ovulate loculi sometimes subdivided nearly to the placentae or alternating with an equal number of empty loculi; ovules collateral, pendulous; styles free or united at the base, slender, with simple capitate or clavate stigmas
Fruit a capsule dehiscing septicidally into (4) 5 2-seeded valves, or septicidally and loculicidally into (8) 10 1-seeded valves, or a drupe usually with fewer seeds than the 2–5 originally fertile loculi
Seeds ± compressed, shining, exarillate, with or without endosperm; embryo straight or slightly curved, with flat cotyledons


Linaceae DC. ex Perleb appears in other Kew resources:

First published in Vers. Arzneikr. Pfl. 107. 1818 [May 1818] (as "Lineae") (1818)

Accepted by

  • APG IV (2016) http://dx.doi.org/10.1111/boj.12385


Flora Zambesiaca
Flora Zambesiaca

Flora of Tropical East Africa
Flora of Tropical East Africa

Flora of West Tropical Africa
Flora of West Tropical Africa

Interactive Key to Seed Plants of Malesia and Indo-China
The Malesian Key Group (2010) Interactive Key to Seed Plants of Malesia and Indo-China (Version 2.0, 28 Jul 2010) The Nationaal Herbarium Nederland Leiden and The Royal Botanic Gardens Kew

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics.