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Plantago

See list of 12 species in this genus

References: Bassett (1973), Rahn (1996).

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P. coronopus
1a. Leaf blades dentate to 1- or 2-times pinnately lobed; corolla pubescent on the abaxial  (i.e., outer) surface; spike nodding prior to anthesis
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1b. Leaf blades usually entire (sometimes with obscure teeth); corolla glabrous on the abaxial surface or pubescent in P. maritima; spike not nodding prior to anthesis
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  P. arenaria
  2a. Leaves borne on a stem, opposite, the blades linear and 1–3 mm wide [Fig. 774]; peduncles arising from the axils of leaves [Fig. 774]
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  2b. Leaves all basal, the blades linear to ovate and 1–110 mm wide [Fig. 774]; peduncles arising among basal rosettes of leaves [Fig. 775]
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    3a. Bracts and/or sepals conspicuously pubescent; plants monocarpic, usually annual (sometimes biennial)
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      P. virginica
      4a. Plants subdioecious; lobes of the corolla of carpel-bearing, chasmogamous flowers erect after anthesis, connivent, closing over the fruit; leaf blades oblanceolate to obovate
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      4b. Plants synoecious; lobes of the corolla spreading to reflexed after anthesis; leaf blades linear to narrow-oblong
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        P. aristata
        5a. Bracts conspicuously exceeding the flowers and fruits, the lower ones 8–45 mm long, mostly 4–10 times as long as the sepals [Fig. 775]; leaf blades sparsely villous to nearly glabrous on the adaxial surface; inflorescence sparsely tomentose
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        P. patagonica
        5b. Bracts inconspicuous, scarcely, if at all, extending beyond the flowers and fruits, 2–5.4 mm long, mostly 1–3 times as long as the sepals; leaf blades evidently villous-tomentose on the adaxial surface; inflorescence evidently tomentose
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    3b. Bracts and sepals glabrous or ciliate only on the apical portion of the keel; plants polycarpic, perennial (monocarpic and annual in P. pusilla)
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      P. pusilla
      6a. Flowers with 2 stamens; corolla lobes 0.25–0.5 mm long; plants annual
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      6b. Flowers with 4 stamens; corolla lobes 0.7–2.5 mm long; plants perennial
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        P. maritima
        7a. Leaf blades linear, 1–12 mm wide, fleshy; corolla tube pubescent on the abaxial surface; plants of tidal wetlands and Atlantic coast shorelines
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        7b. Leaf blades narrow-elliptic to broad-ovate or obovate, 6–110 mm wide, herbaceous to somewhat fleshy; corolla tube glabrous on the abaxial surface; plants of upland habitats, often weedy (of saline shores in P. intermedia)
        
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        8a. Bracts and sepals conspicuously keeled; lobes of the corolla 0.7–1 mm long; pyxis 4- to 34-seeded; all the roots slender and filamentous; spikes 5–30 cm tall
        
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        P. rugelii
        9a. Pyxis (3–) 4–6 mm tall, circumscissile near the base, containing 4–9 (–10) seeds; bracts narrow-triangular; seeds 1.5–2 (–2.5) mm long, not reticulate-patterned; petiole usually anthocyanic near the base
        
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        9b. Pyxis (2–) 2.5–4 mm tall, circumscissile near the middle, containing 6–22 (–34) seeds; bracts broad-ovate; seeds 1–1.7 mm long, reticulate-patterned; petiole usually green near the base (but sometimes anthocyanic in P. major)
        
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        P. major
        10a. Pyxis rounded to pointed at the apex, containing (4–) 6–11 (–13) seeds; leaf blades membranaceous to fleshy-herbaceous, glabrous or pubescent, broad-elliptic to broad-ovate, borne on relatively more elongate and slender petioles; plants of primarily inland habitats, casually found bordering saline communities
        
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        P. intermedia
        10b. Pyxis broadly rounded at the apex, containing 14–34 seeds; leaf blades subcoriaceous-fleshy, usually pubescent, narrow-elliptic to ovate, borne on broad, short petioles; plants of saline shores and near coastal habitats
        
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        8b. Bracts and sepals flat or slightly keeled; lobes of the corolla 1.5–2.5 mm long; pyxis 2- to 4-seeded; primary roots prominently thickened, tuberous near junction with foliage; spikes 1.5–10 cm tall
        
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        P. lanceolata
        11a. Calyx apparently composed of 3 sepals, 1 of the sepals with 2 midveins and formed by fusion of 2 sepals; leaf blades lanceolate to narrow-elliptic, ascending; scape prominently furrowed
        
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        P. media
        11b. Calyx composed of 4 distinct sepals; leaf blades elliptic to ovate or obovate, prostrate; scape not furrowed

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