Origin and Habitat: Texas (Hood, Wise, Brown, Hamilton, Montague and Young Counties), USA.
Altitude range: Above 180 meters.
Habitat and ecology: Escobaria viviparaSN|9953]]SN|9953]] var. radiosa grows in grasslands and woodlands, on limestone soils. Blooming from May to June.

• Escobaria vivipara var. radiosa (Engelm.) D.R.Hunt
• Cactus radiosus (Engelm.) J.M.Coult.
• Coryphantha fragrans Hester
• Coryphantha neovivipara var. radiosa (Engelm.) Y.Itô
• Coryphantha radiosa (Engelm.) Rydb.
• Coryphantha vivipara var. radiosa (Engelm.) Backeb.
• Echinocactus radiosus (Engelm.) Poselg.
• Escobaria radiosa (Engelm.) G.Frank
• Mammillaria radiosa Engelm.
• Mammillaria radiosa var. neomexicana (Engelm.) C.F.Först.
• Mammillaria vivipara subs. radiosa (Engelm.) Engelm.
• Mammillaria vivipara var. radiosa (Engelm.) Engelm.
• Neomammillaria radiosa (Engelm.) Rydb.

• Escobaria vivipara (Nutt.) Buxb.
• Cactus viviparus Nutt. in Fraser
• Coryphantha vivipara (Nutt.) Britton & Rose
• Mammillaria radiosa var. vivipara (Nutt.) Schelle
• Mammillaria vivipara (Nutt.) Haw.
• Escobaria columnaris (Lahman)
• Coryphantha columnaris Lahman
• Escobaria neovivipara (Y.Itô)
• Coryphantha neovivipara Y.Itô
• Escobaria oklahomensis (Lahman) Buxb.
• Coryphantha oclahomensis Lahman
• Coryphantha oklahomensis Lahman
• Escobaria oclahomensis (Lahman) Buxb.
• Escobaria vivipara var. arizonica (Engelm.) D.R.Hunt
• Coryphantha arizonica (Engelm. in W.H.Brewer & S.Watson) Britton & Rose
• Coryphantha neovivipara var. arizonica (Engelm. in W.H.Brewer & S.Watson) Y.Itô
• Coryphantha vivipara var. arizonica (Engelm. in W.H.Brewer & S.Watson) W.T.Marshall
• Escobaria arizonica (Engelm. in W.H.Brewer & S.Watson) Buxb.
• Mammillaria arizonica Engelm. in W.H.Brewer & S.Watson
• Mammillaria radiosa var. arizonica (Engelm. in W.H.Brewer & S.Watson) K.Schum.
• Mammillaria radiosa f. arizonica (Engelm.) Schelle
• Mammillaria vivipara var. arizonica (Engelm. in W.H.Brewer & S.Watson) L.D.Benson
• Escobaria vivipara var. bisbeeana (Orcutt) D.R.Hunt
• Coryphantha bisbeeana Orcutt
• Coryphantha vivipara var. bisbeeana (Orcutt) L.D.Benson in L.D.Benson
• Coryphantha vivipara var. bisbeeana f. sonorensis P.C.Fisch.
• Coryphantha vivipara f. sonorensis P.C.Fisch.
• Escobaria bisbeeana (Orcutt) Borg
• Mammillaria bisbeeana (Orcutt) Orcutt ex Backeb.
• Escobaria vivipara var. buoflama (P.Fischer) N.P.Taylor
• Coryphantha vivipara var. buoflama P.C.Fisch.
• Escobaria vivipara var. kaibabensis (P.Fischer) N.P.Taylor
• Coryphantha vivipara var. kaibabensis P.C.Fisch.
• Escobaria vivipara var. neomexicana (Engelm.) Buxb. in Krainz
• Cactus neomexicanus (Engelm.) Small
• Cactus radiosus var. neomexicanus (Engelm.) J.M.Coult.
• Coryphantha neomexicana (Engelm.) Britton & Rose
• Coryphantha neovivipara var. neomexicana (Engelm.) Y.Itô
• Coryphantha radiosa var. neomexicana (Engelm.) Schelle
• Coryphantha vivipara var. neomexicana (Engelm.) Backeb.
• Escobaria neomexicana (Engelm.) Buxb.
• Mammillaria neomexicana (Engelm.) A.Nelson
• Mammillaria vivipara subvar. neomexicana Engelm.
• Escobaria vivipara var. radiosa (Engelm.) D.R.Hunt
• Cactus radiosus (Engelm.) J.M.Coult.
• Coryphantha fragrans Hester
• Coryphantha neovivipara var. radiosa (Engelm.) Y.Itô
• Coryphantha radiosa (Engelm.) Rydb.
• Coryphantha vivipara var. radiosa (Engelm.) Backeb.
• Echinocactus radiosus (Engelm.) Poselg.
• Escobaria radiosa (Engelm.) G.Frank
• Mammillaria radiosa Engelm.
• Mammillaria radiosa var. neomexicana (Engelm.) C.F.Först.
• Mammillaria vivipara subs. radiosa (Engelm.) Engelm.
• Mammillaria vivipara var. radiosa (Engelm.) Engelm.
• Neomammillaria radiosa (Engelm.) Rydb.
• Escobaria vivipara var. rosea (Clokey) D.R.Hunt
• Coryphantha alversonii var. exaltissima Wiegand & Backeb. in Backeb.
• Coryphantha rosea Clokey
• Coryphantha vivipara var. rosea (Clokey) L.D.Benson in L.D.Benson

• Escobaria vivipara var. deserti (Engelm. in W.H.Brewer & S.Watson) W.T.Marshall
• Cactus radiosus var. deserti (Engelm. in W.H.Brewer & S.Watson) J.M.Coult.
• Coryphantha chlorantha var. deserti (Engelm. in W.H.Brewer & S.Watson) Backeb.
• Coryphantha deserti (Engelm. in W.H.Brewer & S.Watson) Britton & Rose
• Coryphantha vivipara var. deserti (Engelm. in W.H.Brewer & S.Watson) W.T.Marshall
• Escobaria deserti (Engelm. in W.H.Brewer & S.Watson) Buxb.
• Mammillaria deserti Engelm. in W.H.Brewer & S.Watson
• Mammillaria radiosa var. deserti (Engelm. in W.H.Brewer & S.Watson) K.Schum.
• Mammillaria radiosa f. deserti (Engelm. in W.H.Brewer & S.Watson) Schelle
• Mammillaria vivipara var. deserti (Engelm. in W.H.Brewer & S.Watson) L.D.Benson
• Escobaria chlorantha (Engelm. ex Wheeler) Buxb.
• Cactus radiosus var. chloranthus (Engelm. ex Wheeler) J.M.Coult.
• Coryphantha chlorantha (Engelm. ex Wheeler) Britton & Rose
• Mammillaria chlorantha Engelm. ex Wheeler
• Mammillaria radiosa f. chlorantha (Engelm.) Schelle
• Mammillaria vivipara var. chlorantha (Engelm. ex Wheeler) L.D.Benson

Description: Escobaria viviparaSN|9953]]SN|9953]] var. radiosa is one of the varieties of Escobaria viviparaSN|9953]]SN|9953]] 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 fragransSN|10002]]SN|10002]] Hester is often placed under the synonymy of Escobaria viviparaSN|9953]]SN|9953]] var. radiosa as it seems to fit more closely that taxon than any other.

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