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See list of 15 species in this genus

Reference: Adams and Robson (1961).

  • 1a. Flowers with 4 sepals in unequal groups of 2 and 4 petals [Fig. 687]; styles 2; low, compact, mat- or mound-forming shrubs up to 3 dm tall
  • 1b. Flowers with 5 sepals and 5 petals [Figs. 684,685,686]; styles 3 or 5 (rarely 4); shrubs 5–30 dm tall or herbs
    • 2a. Plants woody; capsules 3-locular (rarely 4-locular)
      • 3a. Inflorescence of solitary, terminal flowers (rarely as many as 3 flowers together); longer sepals 10–15 mm long; petals 10–20 mm long; placentae of fruit not meeting in the center
      • 3b. Inflorescence a terminal cyme of (1–) 3 or more flowers (and sometimes also of axillary cymules); longer sepals 2–7 mm long; petals 4.5–10 mm long; placentae of fruit meeting in center
        • 4a. Terminal cyme with (1–) 3–7 flowers; leaf blades (4–) 7–15 mm wide; capsules 7–14 (–15) ×3–5 mm; seeds 1.5–2 mm long
        • 4b. Terminal cyme with 7 or more flowers; leaf blades 3–7 (–11) mm wide; capsules 4.5–6 ×1.5–3 mm; seeds 0.8–1.3 mm long
    • 2b. Plants herbaceous; capsules 1-, 3-, or 5-locular (rarely 4-locular)
      • 5a. Flowers with 5 styles; capsules 5-locular, 15–30 mm tall; petals 25–30 mm long
      • 5b. Flowers with 3 (–4) styles; capsules 1- or 3-locular (rarely 4-locular), 2–7 mm tall; petals 2–12 mm long
        • 6a. Styles connate or closely connivent, persistent in fruit and appearing as a single, straight beak at the summit of the capsule [Fig. 686]; stigmas minute
          • 7a. Sepals distinctly unequal, 5–13 (–15) ×2–3 (–8) mm; petals 10–13 mm long, strongly asymmetrical, relatively straight on one margin and srongly convex on the other margin; stamens numbering 120–200, deciduous; seeds 1.5–1.8 mm long; stems branched near or base or throughout and usually clustered together
          • 7b. Sepals subequal to somewhat unequal, (2–) 4–7 ×1–3 mm; petals 5–8 mm long, ± symmetrical to weakly asymmetrical; stamens numbering 60–95, persistent; seeds 0.7–0.8 mm long; stems commonly unbranched until inflorescence and occurring singly
            • 8a. Leaf blades with flat margins, elliptic to elliptic-oblong, 1–3 (–4) cm long, 2–3 times as long as wide; sepals oblanceolate to narrow-obovate, widest above the middle
            • 8b. Leaf blades with revolute margins, narrow-lanceolate to narrow-oblong or narrow-elliptic, 3–6 cm long, 4–6 times as long as wide; sepals lanceolate to ovate, widest near or below the middle
        • 6b. Styles distinct nearly to the base and often divergent, deciduous in fruit and not appearing as a single beak at the summit of the capsule; stigmas capitate
          • 9a. Ovary and capsule 3-locular (rarely 4-locular); flowers with 20–40(–70) stamens
            • 10a. Petals conspicuously dotted and streaked with black; sepals with few or no black glands, obtuse to broad-acute at the apex; seeds 0.5–0.7(–1.1) mm long; branches terete, without decurrent ridges; capsules 2.5–6 mm tall, with black glands arranged in longitudinal streaks or broader shapes only
            • 10b. Petals dotted only at margins; sepals copiously dotted and lined with black glands, acuminate at the apex; seeds (0.9–)1–1.2(–1.3) mm long; branches with sharp, decurrent ridges below the leaves; capsules 6–10 mm tall, with black glands arranged both in both longitudinal and oblique streaks
          • 9b. Ovary and capsule unilocular; flowers with 5–22 stamens
            • 11a. Leaf blades subulate to linear-subulate, 1-nerved, appressed, 1–4 mm long; inflorescence frequently monochasial (i.e., with alternate branches)
            • 11b. Leaf blades linear to elliptic, 1- to 7-nerved, spreading to ascending, 3–45 mm long; inflorescence clearly dichasial (i.e., with opposite branches)
              • 12a. Capsules ellipsoid, abruptly tapered and rounded at the summit [Fig. 684]; sepals linear to linear-lanceolate, broadest at or near the middle; stems decumbent and leafy-bracted at the base
              • 12b. Capsules ellipsoid-conic to conic, gradually tapered and pointed at the summit [Fig. 685]; sepals lanceolate, broadest below the middle; stems erect, not leafy-bracted at the base (though with leafy stolons)
                • 14a. Leaf blades linear to narrow-oblanceolate, 1–4 (–6) mm wide, 1- or 3-nerved (rarely 5-nerved), narrowly tapering to the base [Fig. 685]; petals 2.5–3 mm long
                • 14b. Leaf blades lanceolate to narrow-elliptic or narrow-oblong, 3–9 (–15) mm wide, 5- or 7-nerved, broadly tapering to rounded at the base; petals 3.5–4 mm long

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 Show photos of:   Each photo represents one species in this genus.