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Escobaria vivipara var. radiosa (Engelm.) D.R.Hunt

Family: CACTACEAE · Variety or form of Escobaria vivipara

Publication: Cact. Succ. J. Gr. Brit. 40(1): 13 (1978).

Description

Escobaria vivipara var. radiosa is one of the varieties of Escobaria vivipara which is a somewhat variable taxon with several collected forms that were early published as full species or as varieties, but these were too weak botanically to stand, so they are all combined in E. vivipara, and the two plants are not readily distinguishable, if not for the geographical provenance. More likely they are one and the same species.

Distinguishing characteristics of var. radiosa:

Stems: Ovate or cylindrical, about 5 cm high and in diameter sometimes proliferous (with freely asexual propagating shoots), tubercles terete, dark green in 13 oblique rows.

Spines: Relatively dense, obscuring stems to varying degrees.

Radial spines: 20-30(-40) per areole, 1.2-1.9 cm long, white to pink, very unequal.

Central spines: 3-4(-5) per areole, stouter and longer, (8-)15-22 mm long, straight, mostly white basally but tipped with pink, red, or black, upper ones longer, lowest shorter and horizontal.

Flowers: 4-5 cm in expansion and about same diameter when fully open, light violet to dark purple; stigmas obtuse deep velvety purple. The flowers open three days in direct sunshine only and later than most Cactaceae from 12 or 1 till 3 or 4 o’clock The flower buds are formed in the axils of the first tubercles of the season but are immediately pushed aside by a continuous growth of more tubercules, the buds as well as the flowers and fruits are therefore lateral.

Fruits: Green, 1.9- 2.5 cm long.

Seeds: Brown, reticulate.

Taxonomic notes: Coryphantha fragrans Hester is often placed under the synonymy of Escobaria vivipara var. radiosa as it seems to fit more closely that taxon than any other.

Origin and Habitat

Texas (Hood, Wise, Brown, Hamilton, Montague and Young Counties), USA.

Altitude range: Above 180 meters.

Habitat and ecology: Escobaria vivipara var. radiosa grows in grasslands and woodlands, on limestone soils. Blooming from May to June.

Bibliography

Major references and further lectures

  1. George Engelmann, Asa Gray “Plantae Lindheimerianae: An Enumeration of F. Lindheimer’s Collection of Texan Plants, with Remarks and Descriptions of New Species, Etc” Freeman and Bolles, 1845

  2. Elaine Nowick “Historical Common Names of Great Plains Plants, with Scientific Names Index: Volume II: Scientific Names Index” Lulu.com, 2014

  3. Cyrus Longworth Lundell “Flora of Texas”, Volume 2 University Press, Southern Methodist University, 1969

  4. Escobaria vivipara var. radiosa in: “SIDA, Botanical Miscellany” Herbarium, Southern Methodist University, 1999

  5. Liberty Hyde Bailey, Wilhelm Miller “Cyclopedia of American Horticulture, Comprising Suggestions for Cultivation of Horticultural Plants, Descriptions of the Species of Fruits, Vegetables, Flowers and Ornamental Plants Sold in the United States and Canada, Together with Geographical and Biographical Sketches”, Volume 2, Macmillan, 1909