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The Nichol Turk's head cactus is a relatively small (to 20 cm wide, 30 cm high) globular cactus, single-stemmed, globose, blue-green in color. Each areole has three strong red central spines, sometimes partly black in older plants. Five thinner radial spines surround the central three. Small seedlings around the base lend plants the appearance of being multi-stemmed. Mature plants are eight-ribbed. The apical meristem is protected by whitish-yellow wool, which shades developing flower buds and fruits. Flowers are a beautiful intense pink, and fruits are light in color, fleshy and ephemeral. Once fruits are open, the rough black seeds (2 mm in diameter) lie on the wool atop plants, with seeds rolling off between the ribs. Because of the slow growth rate of plants, it appears that Echinocactus horizonthalonius v. nichollii may have a life-span of 75-100 years.
The habitat is primarily on alluvial fans composed of limestone-derived soils in the Waterman and Vekol Mountains. Some plants can be found growing on bedrock terraces and saddles on the mountain. Plants growing on alluvial fans form dendritic patterns. On both bedrock and alluvial fans, trees and shrubs are scarce, rpoviding open, sunny habit for these cacti. Those located beneath shrubs and trees had lower survival rates than those in the open.
In 1979, when this variety was first listed as endangered, threats included copper mining, urban development, off-road vehicle use and over-collection. No evidence of grazing could be found on the BLM-administered site at that time. Currently, limestone quarrying, urban development, off-road vehicle use, and collecting remain as serious threats to these plants. Subsequent erosion after disturbances is highly damaging to these cacti. Because it is estimated that over 10,000 individuals comprise both populations, there is a misconception that threats can be buffered by the number of individual plants. However, considering the advanced ages of sizeable plants, and the rapid decrease in available growing sites, these plants are in imminent danger of being extirpated.
Plants in the Garden collection number over 160, with over 700 seeds. The plants were salvaged from two sites and were collected in 1991 and 1993 from the Waterman Mountains. Almost 500 seeds were produced in cultivation, and additional seeds have been collected, but not accessioned, because they were from open-pollinated plants. Collected plants were initially heeled in a temporary sand bed until it could be decided where they would go. Many of the plants were potted into a sandy native soil and placed in the propagation area of the Garden. Seeds were processed and stored according to CPC guidelines. The plants would be used to produce seeds in a carefully controlled pollination attempt, to aviod any contamination with pollen from other taxa. One such attempt, accomplished by enclosing a group of flowering plants with a fine nylon netting, produced 462 seeds. Additional attempts will be made in an effort to build a seedbank of the species sufficiently large to use for reintroduction, if necessary.
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