Draba petrophila |
Brassicaceae tribe Arabideae |
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Santa Rita Mountain Draba, Santa Rita Mountain whitlowgrass, Santa Rita whitlow grass |
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Habit | Perennials; (cespitose, long-lived); caudex simple or branched (covered with persistent petioles), not scapose. | Annuals, biennials, or perennials [subshrubs]; eglandular. |
Stems | usually unbranched, rarely branched, 0.3–1.9(–2.8) dm, moderately to densely hirsute throughout, trichomes simple, 0.2–1.3 mm, with short-stalked to subsessile, cruciform, 0.02–0.4 mm, and 2-rayed ones, 0.3–0.9 mm. |
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Basal leaves | rosulate; petiolate; petiole ciliate, (trichomes simple, 0.4–1.5 mm); blade oblanceolate, 1–5(–6) cm × 2–5(–10) mm, margins usually entire, rarely denticulate, surfaces pubescent, abaxially with stalked, cruciform trichomes, 0.07–0.5 mm, adaxially often similar, sometimes with fewer, simple and 2-rayed trichomes, 0.4–1.3 mm. |
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Cauline leaves | 3–10; sessile; blade ovate to lanceolate or oblong, margins entire or denticulate, surfaces pubescent as basal. |
petiolate or sessile; blade base auriculate or not, margins entire or dentate. |
Racemes | 10–37(–58)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. |
usually ebracteate, often elongated in fruit. |
Flowers | sepals oblong, 2–3.5 mm, pubescent, (trichomes simple and 2-rayed); petals yellow, oblanceolate, 3.5–6 × 1.2–1.8 mm; anthers oblong, 0.8–1 mm. |
actinomorphic; sepals erect, ascending, or spreading, lateral pair seldom saccate basally; petals white, yellow, orange, pink, or purple, claw usually present, usually distinct; filaments unappendaged, not winged; pollen 3-colpate. |
Fruiting pedicels | divaricate-ascending, straight, 4–10 mm, pubescent throughout, trichomes simple (0.1–0.5 mm) and subsessile, 2–4-rayed, (0.03–0.2 mm). |
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Fruits | lanceolate to elliptic, often strongly twisted, flattened, 5–11 × 2–3 mm; valves puberulent at least along margin, trichomes simple, antrorse, 0.03–0.15 mm; ovules 14–24 per ovary; style 0.8–1.8(–2.5) mm. |
silicles or siliques, usually dehiscent, very rarely indehiscent, unsegmented, latiseptate or terete; ovules 2–70(–88)[–110+] per ovary; style usually distinct, sometimes obsolete; stigma usually entire, rarely 2-lobed. |
Seeds | ovoid, 1–1.4 × 0.6–0.9 mm. |
biseriate or uniseriate [rarely aseriate]; cotyledons accumbent. |
Trichomes | stalked or sessile, usually stellate, dendritic, cruciform, or forked, sometimes mixed with simple ones, rarely malpighiaceous. |
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Draba petrophila |
Brassicaceae tribe Arabideae |
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Phenology | Flowering Jul–Sep. | |
Habitat | Crevices, ledges of cliffs | |
Elevation | 1200-2800 m (3900-9200 ft) | |
Distribution |
AZ
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North America; Mexico; South America; Europe; Asia; n Africa |
Discussion | Draba petrophila is often broadly circumscribed to include the taxon herein called D. viridis. For a discussion of the differences between these species and the closely related D. helleriana, see I. A. Al-Shehbaz and M. D. Windham (2007). Draba petrophila, in the strict sense, is known only from Cochise, Pima, and Santa Cruz counties in southeastern Arizona. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Genera 8, species ca. 460 (4 genera, 139 species in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 329. | FNA vol. 7, p. 256. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | D. helleriana var. blumeri, D. helleriana var. petrophila | |
Name authority | Greene: Pittonia 4: 17. (1899) | de Candolle: Mém. Mus. Hist. Nat. 7: 229. (1821) |
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