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Linaceae
This family contains exactly one genus, Linum.
See list of 9 species in this genusSee McDill et al. (2009) for rationale of including Radiola in Linum. Reference: Rogers (1963).
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1a. Flowers with 4 sepals, petals, stamens, and styles; sepals with 3 apical lobes; leaf blades 2–3 mm long; plants diminutive annuals, 3–10 cm tall
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1b. Flowers with 5 sepals, petals, stamens, and styles; sepals without apical lobes, though sometimes ciliate or toothed along the margin; leaf blades 3–35 mm long; plants annual or perennial, 10–100 cm tall
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2a. Petals blue, 10–23 mm long; capsules 5–10 mm wide; sepals without glands
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3a. Leaf blades with 3 nerves; sepals 7–9 mm long at maturity, the inner ciliolate; plants annual
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3b. Leaf blades with 1 nerve, sometimes with 2 additional, obscure nerves; sepals 5–7 mm long at maturity, eciliolate; plants perennial
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2b. Petals white or yellow, 3–10 mm long; capsules 2–2.5 mm wide; at least the inner sepals glandular-ciliate, glandular-toothed, or with sessile marginal glands (sometimes entire in L. striatum)
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4a. Petals white; lower pedicels 10–25 mm long; staminodes present; plants annual
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4b. Petals yellow; pedicels up to 8 (–10) mm long; staminodes absent; plants perennial or annual in L. sulcatum
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5a. Styles connate at the base for a distance of 0.3–1.5 mm; leaf blades with a pair of dark glands at the base (i.e., stipular glands); plants annual
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5b. Styles distinct; leaf blades lacking a pair of basal glands; plants perennial
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6a. Fruit obturbinoid, as tall as or taller than wide, pointed at the apex [Fig. 712], 2–3 mm tall; false septa of fruit incomplete (though the fruit still separating into 10 mericarps at maturity)
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6b. Fruit depressed globose, shorter than wide, rounded to bluntly pointed at the apex [Fig. 713], 1.3–2 mm tall; false septa of fruit nearly complete
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7a. Inner sepals evidently glandular-toothed [Fig. 713]; leaf blades linear to narrow-lanceolate or lanceolate-elliptic, the larger ones (1–) 1.5–3.5 (–4) mm wide
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7b. Inner sepals entire or with sessile, marginal glands; leaf blades elliptic to oblanceolate or obovate, the larger ones 3–10 mm wide
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8a. Branches striate-angled; inflorescence elongate, panicle-like; true septa of fruit, as well as the false septa, eciliate
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8b. Branches ± terete; inflorescence broad, corymb-like; true septa of fruit usually sparsely ciliate
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Each photo represents one species in this genus.