|
''Sclerocactus'' ("hard cactus", from Greek; refers to the hard, dry fruit) is a genus of cacti. It comprises about 15 species, the exact number depending on the authority. These species are very xerophytic. They are sometimes called 'fishhook cactus' or 'little barrels.' ==Description== ''Sclerocactus'' are ovoid to elongate cylindric, have rigid stems with tubercles that are generally coalesced into ribs, and are covered with spines that come out of the areoles.〔 Most species have at least one hooked spine at each areole. Less often, species may not have hooks. These plants are found in higher elevation deserts such as on the Colorado Plateau, or in the Mohave Desert or the Great Basin. They are well suited to extremes due to lack of rainfall, hot summers and below freezing winters. The Little barrel cactus typically grows in areas where water flows irregularly or depressions where water can accumulate for short periods of time. They are most often found growing along washes and arroyos where their seeds have been subjected to scarification due to water movement, but they oddly also tend to grow along ridges in spots where depressions have formed and can hold water for some period of time. The sometimes hooked or curved spines and the armored web of spines enclosing the cactus body in species of this genus is an adaptation which allows the plant to move to more favorable locations. This plants seeds germinate in areas where water movement occurs or in areas where standing water accumulates for some period of time, and during flash floods, the hooked spines allow the plants to be caught on water borne debris and be uprooted and carried to areas where water tends to accumulate. A large percentage of plants in habitat show signs of water debris damage along the stems which has healed and are found growing on their sides in places where floodwaters have deposited them. The habitat these plants exist in is very arid, and the plants have adapted to exploit water movement to concentrate their biomass in areas where water is likely to be present. 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」の詳細全文を読む スポンサード リンク
|