Herbs or subshrubs, annual or perennial, rarely with woody caudex. Stems terete, ridged, or sulcate. Leaves alternate, opposite, or whorled; stipular glands present or absent; blade margins entire or glandular-toothed, sometimes ciliate. Flowers homostylous; sepals persistent or deciduous, margins scarious or not, glandular-toothed or not; petals yellow, sometimes with maroon at base; staminodia present or absent; styles distinct or connate nearly to apex; stigmas usually capitate, rarely linear. Capsules dehiscing into 10, 1-seeded segments or 5, 2-seeded segments; false septa incomplete to complete. Pollen tricolpate or multiporate.

Distribution

Nearly worldwide.

Discussion

Species ca. 85 (30 in the flora).

Selected References

Rogers, C. M. 1982. The systematics of Linum sect. Linopsis (Linaceae). Pl. Syst. Evol. 140: 225–234.

Lower Taxa

Linum alatum, Linum allredii, Linum arenicola, Linum aristatum, Linum australe, Linum berlandieri, Linum carteri, Linum compactum, Linum elongatum, Linum floridanum, Linum harperi, Linum hudsonioides, Linum imbricatum, Linum intercursum, Linum kingii, Linum lundellii, Linum macrocarpum, Linum medium, Linum neomexicanum, Linum puberulum, Linum rigidum, Linum rupestre, Linum schiedeanum, Linum striatum, Linum subteres, Linum sulcatum, Linum trigynum, Linum vernale, Linum virginianum, Linum westii

Key

1	Styles distinct.	> 2
2	Stigmas linear [subsect. Halolinum].	Linum trigynum
2	Stigmas capitate [subsect. Linopsis].	> 3
3	Stipular glands present [ser. Linopsis].	> 4
4	Proximal leaves in whorls of 4.	Linum schiedeanum
4	Proximal leaves opposite or alternate.	> 5
5	Styles 2–3 mm; petals 4–6.5 mm; Florida.	Linum arenicola
5	Styles 3–6.5 mm; petals 7–11 mm; New Mexico, Texas.	Linum rupestre
3	Stipular glands absent.	> 6
6	False septa incomplete, proximal margins ciliate.	> 7
7	Capsules turbinate, 2–3 mm; anthers 0.5–1 mm; c, e United States [ser. Virginianum (in part)].	Linum intercursum
7	Capsules triangular-ovoid to broadly ovoid or ovoid-pyriform, 2.3–4 mm; anthers 1–2.5 mm; w United States [ser. Neomexicana].	> 8
8	Annuals, 15–60 cm; inflorescences thyrses; styles 1.5–3 mm; capsule apices obtuse.	Linum neomexicanum
8	Perennials, 5–30 cm; inflorescences panicles or thyrses; styles 4–7 mm; capsule apices pointed.	Linum kingii
6	False septa nearly complete, proximal margins sparsely or not ciliate [ser. Virginianum (in part)].	> 9
9	Capsules 1.3–2.3 mm, depressed-globose (broader than long) or globose, apices depressed.	> 10
10	Margins of inner sepals usually glandular-toothed, rarely entire; mature capsule segments usually persistent on plant.	Linum medium
10	Margins of inner sepals eglandular or with a few small sessile glands; mature capsule segments falling freely.	> 11
11	Inflorescences corymbs; pedicels 1–10 mm; carpels flattened or ± concave abaxially.	Linum virginianum
11	Inflorescences panicles; pedicels 0–4 mm; carpels convex abaxially.	Linum striatum
9	Capsules 2–3.9 mm, either pyriform to ovoid or subglobose, apices abruptly short-pointed, obtuse, or 5-apiculate.	> 12
12	Leaves mostly opposite; capsules subglobose, apices abruptly short-pointed.	Linum westii
12	Leaves: proximal usually opposite, distal alternate, rarely all alternate; capsules pyriform to ovoid, apices obtuse or minutely 5-apiculate.	> 13
13	Margins of inner sepals entire; capsules 3.4–3.9 mm; seeds 2.8–3 mm.	Linum macrocarpum
13	Margins of inner sepals glandular-toothed; capsules 2–3.4 mm; seeds 1.6–2.5 mm.	Linum floridanum
1	Styles connate [subsect. Rigida].	> 14
14	Capsules dehiscing into 10, 1-seeded segments; sepals persistent [ser. Sulcata].	> 15
15	Sepals (3.1–)3.6–5(–7.3) mm, apices acuminate.	Linum sulcatum
15	Sepals 2.3–3.7 mm, apices acute.	Linum harperi
14	Capsules dehiscing into 5, 2-seeded segments; sepals deciduous or persistent [ser. Rigida].	> 16
16	Sepal margins not glandular-toothed.	> 17
17	Distal leaves and bracts not ciliate; capsule false septa entirely hyaline, or with cartilaginous portion very narrow, uniform, distal.	Linum hudsonioides
17	Distal leaves and bracts sparsely ciliate; capsule false septa with cartilaginous portion conspicuously broader near base.	Linum imbricatum
16	Sepal margins (some or all) glandular-toothed.	> 18
18	Outer sepals ovate or obovate, margins undulate or crenate, with sessile gland near summit of each crenation.	Linum alatum
18	Outer sepals linear, linear-lanceolate, lanceolate, or narrowly ovate, margins glandular-toothed.	> 19
19	False septa incomplete, proximal margins terminating in loose fringe; sepals persistent.	> 20
20	Styles connate to within 0.8–3 mm of apex; pedicels (5–)20–30(–60) mm; stipular glands absent.	Linum subteres
20	Styles connate to within 0.2 mm of apex; pedicels 2–12 mm; stipular glands usually present.	Linum vernale
19	False septa complete, proximal margins not terminating in loose fringe; sepals usually deciduous.	> 21
21	Plants gray-puberulent throughout or puberulent or glabrescent in proximal 1/3.	> 22
22	Herbs, annual or short-lived perennial, gray-puberulent throughout.	Linum puberulum
22	Subshrubs, puberulent or glabrescent in proximal 1/3, otherwise glabrous.	Linum allredii
21	Plants glabrous, glabrate, scabrous, or puberulent or hirsutulous at base.	> 23
23	Sepals linear-lanceolate.	> 24
24	Petals obovate; stamens 5–7 mm; styles 4.5–7 mm.	Linum aristatum
24	Petals obcordate; stamens 4–5 mm; styles 3–4 mm.	Linum lundellii
23	Sepals lanceolate to narrowly ovate.	> 25
25	Stipular glands usually absent.	> 26
26	Styles 2.5–4 mm, petals 6–11 mm.	Linum compactum
26	Styles 3–11 mm, petals 10–18 mm.	> 27
27	Petals coppery yellow or orange, red-lined or with short pale to deep brown-red zone at base; styles 5–11 mm; sepal apices sharply acute to acuminate; w, c North America.	Linum rigidum
27	Petals orange-yellow throughout; styles 4–6 mm; sepal apices short-awned; s Florida.	Linum carteri
25	Stipular glands usually present at least at some nodes.	> 28
28	Styles 6–9.5 mm.	> 29
29	Petals with prominent wine-colored band proximal to middle.	Linum elongatum
29	Petals reddish below middle.	Linum berlandieri
28	Styles 2–6 mm.	> 30
30	Sepal apices aristate; petals yellow to yellow-orange throughout.	Linum australe
30	Sepal apices acute to acuminate or short-awned; petals yellow to orange, sometimes with reddish base.	> 31
31	Sepal apices short-awned; s Florida.	Linum carteri
31	Sepal apices acute to acuminate; c United States.	> 32
32	Stamens 4–5 mm.	Linum lundellii
32	Stamens 6–8 mm.	Linum rigidum