Opuntiads of the USA(by Joe Shaw and Dave Ferguson)
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MissionOpuntia SpeciesOpuntia Country No.
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Opuntia gilvescens GriffithsIntroductionO. gilvescens is one of the many cacti that has been combined into the O. phaeacantha group of plants by various authors. Herein, O. gilvescens is treated as a distinct taxon, separate and different from O. phaeacantha. See O. phaeacantha for a list of synonyms complied by the USDA Natural Resources Conservation Service. O. gilvescens is a widespread plant; the authors have found it in south Central Oklahoma (Arbuckle Mountains) and west into the panhandle of Texas, in west Texas (anywhere west of a line from Wichita Falls to the Pecos River), in many parts of New Mexico, in Arizona, and in southern Nevada and Utah. The plant is found in Mojave Desert portions of California and perhaps in regions of Colorado. O. gilvescens can be a large plant in warmer areas (e.g., near Las Cruces, NM), or it can be small and ground-hugging in colder regions (south of Cuba, NM about 5,500 ft.). It is frequently found in association with other Opuntia species such as O. cymochila, O. tortispina, O. orbiculata, O. phaeacantha, O. polyacantha, and O. macrocentra. O. gilvescens often grows in sandy soils but it can also occur in rocky areas or in fine soils, the latter if on steep inclines or in areas of little rain. (Jump to images of O. gilvescens.) OR (Jump to the images of O. gilvescens in Arizona.) Technical Description (copyright Dave Ferguson, 2006)The original description by Griffiths is detailed and concise. However, the spines are sometimes a bit more numerous than indicated and may occasionally be yellow or nearly black. The dark spine base may be light or very dark and sometimes the spines are irregularly mottled with color. Another difference from the original description concerns flowers and fruits, which vary considerably according to the condition of the plant. The flowers are typically pale yellow with numerous tepals that give the flower a full appearance. Flowers are generally 2-3 inches across, often 2.5 inches. Fruits are broadly rounded obovate, about 1-1.5 inches long (they may be globose when shorter). Fruits are about 1-1.2 in. wide. Occasionally, fruits may be larger than these dimensions.
Stigmata are usually pale, often pale yellowish or greenish, sometimes nearly white, sometimes a bit more strongly green. Anthers are yellow or cream-colored; filaments are yellow but can darken towards the base. Most O. gilvescens flowers have no red, but some rare individuals may have rust-colored veining that can darken or spread as the flower ages. Plants from southwest New Mexico and adjacent Arizona are often pale; sometimes they have rhombic or more elongate joints and pale spines. Plants from the Mojave Desert area often have round pads with fewer than average areoles, and a few pale spines. Plants from the Chihuahuan Desert of Mexico and into central Texas are often dark in appearance; they may become strongly reddish purple in winter and the spines can be almost black. In central NM O. gilvescens fits the type description exactly, except that areoles, glochids, and spines are darker, and the pads are darker as well. Some populations, as on the e. side of he Sandias and down into Socorro County, and again in the Alamogordo area, often have wide curved pads creating an unusual pile of potato chips look. O. gilvescens can resemble several other species that collectively are very different in appearance, including O. canada, O. camanchica, O. phaeacantha, O. macrocentra, O. sanguinocula. O. gilvescens is not exactly a "chameleon" but some plants may seem to have a feature borrowed from any of the mentioned species.
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shawjoej@gmail.com
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