Physaria didymocarpa |
Physaria thamnophila |
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common twinpod, double twinpod, twin bladderpod |
Zapata 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). | Perennials; caudex simple or branched, (woody); densely (silvery) pubescent, trichomes (short-stalked), 4–8-rayed, rays furcate or bifurcate, (finely tuberculate throughout). | ||||||||
Stems | several from base, decumbent, (unbranched, leafy for the genus), ca. 1 dm. |
simple or few from base, decumbent, (straggling and flexuous, usually branched distally), 4–8 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 narrowly elliptic to oblanceolate, 4–12 cm, margins entire, sinuate, or shallowly dentate, (apex acute). |
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Cauline leaves | blade oblanceolate, 1–2 cm (width 4–8 mm), margins entire or with occasional tooth, (apex acute). |
(sessile or proximal shortly petiolate); blade linear to narrowly elliptic, 3–4 cm, margins entire, sinuate, or remotely dentate, (apex acute). |
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Racemes | congested, (elongated in fruit, greatly exceeding leaves). |
loose, (sometimes greatly elongated). |
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Flowers | sepals lanceolate to oblong, 6–8 mm, (often keeled); petals spatulate, 10–12 mm. |
sepals elliptic, 3.5–4 mm, (lateral pair subsaccate, median pair thickened apically, cucullate); petals broadly obovate, 4–5 mm, (sometimes with short, broad claw). |
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Fruiting pedicels | (spreading, straight or slightly curved), 8–12 mm. |
(recurved), 15–20(–25) 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. |
(pendent), subglobose or broadly ovoid, slightly compressed, 5–7 mm; valves (not retaining seeds after dehiscence), glabrous throughout; ovules per ovary unknown; style 1.5–2 mm. |
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Seeds | flattened. |
flattened. |
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2n | = 16. |
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Physaria didymocarpa |
Physaria thamnophila |
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Phenology | Flowering Apr. | |||||||||
Habitat | Sandy soils, entangled in shrubs, cactus clumps | |||||||||
Elevation | 1700-1800 m (5600-5900 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.) |
Of conservation concern. Physaria thamnophila is found in sandy areas with shrubs and cactus in sparse shrubland communities of Starr and Zapata counties. It sometimes flowers through September with sufficient moisture. (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. 664. | ||||||||
Parent taxa | Brassicaceae > tribe Physarieae > Physaria | Brassicaceae > tribe Physarieae > Physaria | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Vesicaria didymocarpa, Coulterina didymocarpa | Lesquerella thamnophila | ||||||||
Name authority | (Hooker) A. Gray: Gen. Amer. Bor. 1: 162. (1848) | (Rollins & E. A. Shaw) O’Kane & Al-Shehbaz: Novon 12: 328. (2002) | ||||||||
Web links |