Physaria didymocarpa |
Physaria sessilis |
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common twinpod, double twinpod, twin bladderpod |
sessile bladderpod |
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Habit | Perennials; caudex branched, (cespitose); densely pubescent, trichomes (often stalked, appressed to wavy and spreading), several-rayed, rays furcate or simple, (slightly to strongly umbonate, nearly smooth to strongly tuberculate). | Annuals or biennials; with a fine taproot; densely pubescent, trichomes (sessile or short-stalked), 4–6-rayed, rays usually furcate, rarely bifurcate, (moderately tuberculate or nearly smooth). | ||||||||
Stems | several from base, decumbent, (unbranched, leafy for the genus), ca. 1 dm. |
simple or few to several from base, erect, (often distal 1/2 branched), to 6 dm. |
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Basal leaves | (forming a strong rosette; long-petiolate); blade obovate, 1.5–4(–8) cm, (base ± abruptly narrowing to petiole), margins usually repand or dentate, rarely entire, (apex usually angular, surfaces silvery). |
blade oblanceolate, to 9 cm, margins entire, dentate, or sinuate to lyrate-pinnatifid. |
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Cauline leaves | blade oblanceolate, 1–2 cm (width 4–8 mm), margins entire or with occasional tooth, (apex acute). |
(proximal shortly petiolate, distal sessile); blade narrowly elliptic to linear, 2–4(–6) cm, margins entire or repand to shallowly dentate. |
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Racemes | congested, (elongated in fruit, greatly exceeding leaves). |
loose. |
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Flowers | sepals lanceolate to oblong, 6–8 mm, (often keeled); petals spatulate, 10–12 mm. |
sepals elliptic or elongate-ovate, 3.4–5.2(–6.5) mm, (lateral pair subsaccate, median pair thickened apically, cucullate); petals obovate or deltate, 5–10 mm, (sometimes with short claw, margins undulate). |
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Fruiting pedicels | (spreading, straight or slightly curved), 8–12 mm. |
(divaricate-ascending to widely spreading, straight), 8–20 mm. |
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Fruits | (erect), didymous, inflated, 10–20 × 10–20 mm, (papery or firm, basal sinus shallow to deep, sometimes barely notched, apical sinus deep, narrow, usually closed); valves (retaining seeds after dehiscence), loosely pubescent, trichomes spreading (appearing fuzzy); replum obovate to broadly oblong, not constricted, 3–4 mm, as wide as or wider than fruit, apex obtuse; ovules (4–)8 per ovary; style 7–9 mm. |
globose or subglobose, sometimes slightly compressed, 3–6 mm; valves (not retaining seeds after dehiscence), densely papillose, densely pubescent inside, trichomes raised; replum as wide as or wider than fruit; ovules 8–18 per ovary; style 1.5–3.5 mm. |
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Seeds | flattened. |
flattened. |
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2n | = 12. |
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Physaria didymocarpa |
Physaria sessilis |
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Phenology | Flowering and fruiting Apr–Jun. | |||||||||
Habitat | Limestone chip, black soils, grassy roadsides, fields, limestone, oak woodlands, mesquite brush lands, pastures, open dry hills | |||||||||
Elevation | 30-700 m (100-2300 ft) | |||||||||
Distribution |
ID; MT; WA; WY; AB; BC
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TX |
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Discussion | Subspecies 3 (3 in the flora). The characters used to differentiate Physaria didymocarpa from P. saximontana (especially subsp. dentata) appear to be weak at best: whether there are 4 or 8 ovules per ovary and whether the silicle lacks a basal sinus or one is present. There appears to be intergradation in each of those characters. A traditional circumscription of these species is followed here. Further work is needed at both the species and subspecies level in these taxa. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 7, p. 633. | FNA vol. 7, p. 663. | ||||||||
Parent taxa | Brassicaceae > tribe Physarieae > Physaria | Brassicaceae > tribe Physarieae > Physaria | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Vesicaria didymocarpa, Coulterina didymocarpa | Lesquerella gracilis var. sessilis, Lesquerella sessilis | ||||||||
Name authority | (Hooker) A. Gray: Gen. Amer. Bor. 1: 162. (1848) | (S. Watson) O’Kane & Al-Shehbaz: Novon 12: 328. (2002) | ||||||||
Web links |