Pereskiopsis

Opuntioid cacti are usually thought of as having jointed stems that are either round in cross section or flattened, and leaves that are small and ephemeral. The other notable, and unpleasant, feature of the group is their glochids. Pereskiopsis is an unusual member of the subfamily Opuntioideae in some respects, as species of the genus have flat, fleshy, long-lasting leaves similar to those of Pereskia. Pereskiopsis has glochids, however, as well as certain other opuntioid features such as those of the flowers and seeds.

Early researchers were uncertain what to do with species now included in Pereskiopsis, with some being placed in Pereskia, others in Opuntia. Nathaniel Britton and Joseph Rose described Pereskiopsis in 1907, believing the plants belong in their own genus. All subsequent research has supported their decision. The name Pereskiopsis is derived from the Greek opsis, appearance, thus Pereskia-like. Britton and Rose included 10 species in Pereskiopsis but the International Cac-taceae Systematics Group accepts 8. Opuntia brandegeei was designated as type, but that is an illegitimate name, a synonym of Pereskiopsis porteri, the type. Salvador Arias (1996) has clarified the taxonomy of Pereskiopsis in an important study involving both field and laboratory work. The relatively large flowers of Pereskiopsis are usually borne laterally on the stems and open during the day during summer.

Pereskiopsis Britton & Rose 1907

Subfamily Opuntioideae. Plants shrubby ortreelike with several irregular branches, often scramblingor climbing, sometimes with well-defined trunks. Stems round in cross section, not segmented. Leaves elliptical, ovate, spatula shaped, or nearly round, flat, fleshy, usually persistent. Areoles round, hairy, usually with glochids. Spines usually present, one to several, needle-like. Flowers Opivnf/a-llke, borne laterally on stems of previous season but sometimes terminally, open during the day, rotate, yellow to pinkor red; areoles of pericarpels with leaves, scales, and glochids; floral tubes absent. Fruits club shaped, fleshy, indehiscent, often with glochids, sometimes juicy, red or orange, with few seeds. Seeds broadly oval, whitish yellow, 4-5 mm long, arillate, with felt or hairs. Distribution: Mexico south into Guatemala.

Pereskiopsis aquosa (F. A. C. Weber) Britton & Rose 1907

ALFILERILLO, CHIRRI0NCILL0, TASAJILLO, TUNA DE AGUA Opuntia aquosa F. A. C. Weber 1898

Plants shrubby to treelike, branching basally or from above, 2-4 m (6.6-13 ft) high, often with distinct trunks. Stems glabrous, green, glaucous when young, 1-2.5 cm (0.4-1 in) in diameter. Leaves obovate to nearly elliptical, 3.5-8 cm (1.4-3.1 in) long, 2.5-3.2 cm (1-1.3 in) wide, acuminate api-cally. Areoles round, producing long hairs when young, gray. Glochids yellow. Spine usually one, sometimes as many as 4, sometimes absent, rigid, pale yellow to yellowish white, later gray, 0.5-3.6 cm (0.2-1.4 in) long. Flowers borne at the ends ofbranches, golden yellow with reddish tint, 10-16 cm (3.96.3 in) long, 6-7 cm (2.4-2.8 in) in diameter; pericarpels with bracts. Fruits pear shaped, yellowish green, edible, 6-13 cm (2.4-5.1 in) long, 1.6-3.5 cm (0.6-1.4 in) in diameter, with abundant glochids. Distribution: Durango, Jalisco, and Nayarit, Mexico.

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