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''Sclerocactus sileri'', the Siler fishhook cactus, is a rare and very small cactus found mostly in mineral-rich desert areas of intermediate elevations, notably in the American states of Utah, Nevada, and northern Arizona. ==Description== ''Sclerocactus sileri'' grows to about 25 cm tall and 12 cm wide. The cactus also shows a flower of diameter about , with whitish or yellowish petals that show venation in a purple color. Flowering occurs in the spring season. ''Sclerocactus sileri'' has both central and radial spines. Central spines have length up to about and are brownish-black in color. There are four central spines (4-5 per areole),〔http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242415294〕 where the lower central spine is white, abaxial central spines are tinged, is gray-purplish, angled, and strongly hooked and slightly contorted. Central spines are 1.2–3 cm long and 0.5–1 mm wide, curving towards the ground. The two lateral spines are flattened and thicker. The upper central spine is white to tan and is curved and strongly flattened. Radial spines have length up to about and are white in color. There are about 6-8 radial spines per areole which are acicular.〔 Seeds are black to light brown in color, and are 2.2-2.5 mm wide, with a rounded papillae.〔 Flowers and fruits of ''Sclerocactus sileri'' are very similar to others of the same family, such as ''S. whipplei'' or ''S. pubispinus''. The phenology of the flowers from ''Sclerocactus sileri'' bloom during the months of April and May, while the fruits during the months of May and June.〔 Flowers are 2.5–3 cm (1-1.2 in) long and 2.5–3 cm in diameter, with a glabrous exterior floral tube. The outer tepals have brownish and yellowish margins, the larger oblanceolate, 10–15 mm long, mucronate, marginally membranous and crisped or minutely toothed. The inner tepals are yellow, sometimes suffused with brown, the largest lanceolate, 15–25 mm long and mucronate. The filaments are white or greenish white, 7–10 mm long, anthers yellow, about 1 mm long; style yellowish-green, 14–20 mm long; stigma lobes 5-8 and about 1.2-2.5 mm long; ovary 3–7 mm long at anthesis; scales few, membranous, scarious-margined, minutely toothed or fringed.The fruit is green, turning red, ovoid, dry, and 0.8-2.2 cm long. Fruits extend longitudinally, along two to four ventral slits. Black seeds are 2.75–3 mm in diameter and 2.25- 2.5 mm long.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sclerocactus sileri」の詳細全文を読む スポンサード リンク
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