Linaceae DC. ex Perleb

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

Morphology General Habit

Trees, shrubs, rarely herbs; branches sometimes climbing by hooks

Morphology Leaves

Leaves simple, alternate or opposite; stipules present or absent, sometimes gland-like

Morphology Reproductive morphology Flowers

Flowers actinomorphic, hermaphrodite

Morphology Reproductive morphology Flowers Calyx

Sepals 4–5, free or partly united, imbricate

Morphology Reproductive morphology Flowers Corolla

Petals free, contorted, fugacious

Morphology Reproductive morphology Flowers Androecium

Stamens as many as and alternate with the petals, sometimes alternating with small staminodes; filaments connate at base; anthers introrse, 2-celled, opening lengthwise

Morphology Reproductive morphology Flowers Gynoecium

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

Morphology Reproductive morphology Fruits

Fruit a septicidal capsule

Morphology Reproductive morphology Seeds

Seeds compressed, shining, with or without endosperm; embryo straight, cotyledons flat

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

Morphology General Habit

Trees, shrubs, lianes or herbs

Morphology Leaves

Leaves simple, alternate or opposite; stipules present, rarely absent, divided, entire or gland-like

Morphology Reproductive morphology Inflorescences

Inflorescence a terminal or axillary cyme, rarely flowers solitary

Morphology Reproductive morphology Flowers

Flowers regular, hermaphrodite, hypogynous

Morphology Reproductive morphology Flowers Calyx

Sepals 4–5, imbricate, free or partially united

Morphology Reproductive morphology Flowers Corolla

Petals 4–5, contorted in bud, free or partially united at base, often clawed

Morphology Reproductive morphology Flowers Androecium

Stamens 1–3 times as many as sepals; filaments united at base; staminodes sometimes present

Morphology Reproductive morphology Flowers Gynoecium

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

Morphology Reproductive morphology Fruits

Fruit a capsule or drupe

Morphology Reproductive morphology Seeds

Seeds with or without endosperm; embryo straight or slightly curved

Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://creativecommons.org/licenses/by/3.0

Morphology General Habit

Annual or perennial herbs, shrubs or trees

Morphology Leaves

Leaves simple, alternate or opposite, petiolate or sessile, with deciduous stipules or exstipulate, these sometimes modified into glands

Morphology Reproductive morphology Inflorescences

Inflorescences racemes, panicles, terminal spikes or axillary fascicles

Morphology Reproductive morphology Flowers

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

Morphology Reproductive morphology Fruits

Fruit drupaceous, indehiscent or septicidal capsule

Morphology Reproductive morphology Seeds

Seeds alate or not, endosperm abundant, scarce or absent, embryo straight with flattened cotyledons.

Diagnostic

Oily seeds present in Linum. 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). 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. 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 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

Distribution

In the Neotropics Linaceae consists of native (Hebepetalum, Roucheria and Linum), endemic (Linum, Hebepetalum and Roucheria), and cultivated (Linum and Cliococca) species. 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.

Note

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. 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. 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.

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

Morphology General Habit

Trees, shrubs, lianes or herbs, often with tendrils on climbing shoots, glabrous or with an indumentum of simple hairs

Morphology Leaves

Leaves alternate or opposite, simple, penninerved or 1-nerved; stipules divided or entire or gland-like, deciduous (rarely absent)

Morphology Reproductive morphology Flowers

Flowers in terminal or axillary cymes (or rarely solitary), actinomorphic, bisexual, usually heterostylic

Morphology Reproductive morphology Flowers Calyx

Sepals (4) 5, imbricate, free or partially united

Morphology Reproductive morphology Flowers Corolla

Petals (4) 5, contorted in bud, free or very rarely united at the base, often unguiculate, fugacious

Morphology Reproductive morphology Flowers Androecium

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

Morphology Reproductive morphology Flowers Gynoecium

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

Morphology Reproductive morphology Fruits

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

Morphology Reproductive morphology Seeds

Seeds ± compressed, shining, exarillate, with or without endosperm; embryo straight or slightly curved, with flat cotyledons