Sclerocactus spinosior
Woodruff & Benson1976

　　　　　　　　　　　　　

Formerly, this plant has been called "mountain of a black rainbow" in Japan. Black (to dark red-brown) hooked spine and white ribbon-like spine are as the name very beautiful kinds. Although often mixed up with Scl.parviflorus or whipplei, the distribution region is independent in fact and distinction is not difficult from the morphological feature. A distribution region is the mainly Great-basin desert of the western part in Utah. Plants are often living on the soil with much lime with an altitude of 1400-1800m , sometimes hiding itself in the thicket of a sage-brush etc. Plants in cultivation have some difficulty, probably because it was adapted for such severe environment. If water is given too much when they are still in dormancy or a growth phase finishes, even if it is in spring, a root will easy to rot.
Plant size, the diameter of 4-8cm, the height of 5-20cm, and ribs are 6 to 14. Body color is deep green. The spine arrangement changes a lot in the stage of growth. One central spine with densely pubescent is projected from the center of several short radial spines at the time of juvenile. The white-pubescence of spine is known also in S.glaucus and S.pubispinus. But S.parvflorus and S.whipplei do not have such a feature. Also from the above point, S.spinosior can distinguish from them. When plant is reached blooming size, this fine hair of spine will be lost and central spine will turn into strong, black hooked spine and white paper-like spine which surged beautifully. The contrast of entangled spine with black and white is brilliant, and is just suitable to the name of "mountain of a black rainbow". Flowers are about 2-4cm pink - dark purple a little small blooming in May.
The habitat area of S.spinosior is also overlapped with S.pubispinus. Moreover, the plants with the feature of botn species is found in specific area and the possibility of natural crossing is also pointed out. S.spinosior ssp. blainei is regarded as independent species by Heil and Porter. This plant was called S.spinosior ssp. schllesseri before and it has the feature that is small body and the central spine are more entangled compared with species, and the distribution area of ssp.blainei is apart from species. But some expert think it is hard to find out a difference in specific level. This plant is found only by two locality of Nevada. Moreover, these two locality is separated about 70miles distance and no plants are found from the place between two locality. The number of individuals are very few in both locality. It treated as a variation of S.spinosior here for the time being.

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