Origin and Habitat: Cereus spegazziniiSN|7039]]SN|7039]] is reported to occur in Argentina, in the provinces of Santa Fe, Santiago del Estero, Salta, Chaco, and Formosa. It also grows in Bolivia, Brazil, and Paraguay.
Altitude range: It can be found at elevations between 10 and 500 metres above sea level.
Habitat and Ecology: This cactus grows in the interior and edge of dry forests and is common and abundant throughout its range. It is listed as Least Concern because it is widely distributed, is common and locally abundant, and there are no major threats affecting it. It is also present in many protected areas.

• Cereus spegazzinii F.A.C.Weber
• Monvillea spegazzinii (F.A.C.Weber) Britton & Rose
• Piptanthocereus spegazzinii (F.A.C.Weber) Riccobono

• Cereus spegazzinii F.A.C.Weber
• Monvillea spegazzinii (F.A.C.Weber) Britton & Rose
• Piptanthocereus spegazzinii (F.A.C.Weber) Riccobono
• Cereus anisitsii K.Schum.
• Monvillea anisitsii (K.Schum.) A.Berger
• Cereus lindenzweigianus Gürke
• Monvillea lindenzweigiana (Gürke) Backeb. in Backeb. & F.M.Knuth
• Piptanthocereus lindenzweigianus (Gürke) F.Ritter
• Cereus marmoratus hort. ex Schelle
• Cereus ridleii Andrade-Lima ex Backeb.
• Cereus spegazzinii f. cristatus monstruosus hort.
• Monvillea spegazzinii f. cristata monstruosa
• Cereus spegazzinii f. cristatus hort.
• Monvillea spegazzinii f. cristata
• Cereus spegazzinii var. ebenacanthus (F.Ritter) P.J.Braun & Esteves
• Monvillea ebenacantha F.Ritter
• Cereus spegazzinii var. vallegrandensis
• Monvillea vallegrandensis

Description: Cereus spegazziniiSN|7039]]SN|7039]], more commonly known as Monvillea spegazziniiSN|7041]]SN|7041]], is a slender shrubby cactus that has a similar form and habitat to the night-blooming cereus (Peniocereus greggiiSN|8088]]SN|8088]]). It puts forth many basal shoots, soon becoming tillered.
Stems: Branched, bluish mottled in purple and green, erect or semi prostrate , up to 1.8 m long or more, 2 cm inches in diameter;
Roots: Tuberose and succulent, Even adventitious roots of Cereus spegazziniiSN|7039]]SN|7039]] become succulent.
Ribs: Three to five (usually four) raised angular that have deep incisions similar to indentations along the edge. They are about 3 cm long at the base and bear small areoles at the apex of the protuberances.
Central spines: One (or any) up to 1.5 cm long.
Radial spines: The Young plants usually have three sharp, blackish spines 5 mm long, two pointing upward and one downward. On the older parts there are five radial and one central spine, 1.5 cm. long.
Flowers: 10 to 13 cm in length with a slender tube, reddish outer perianth segments and white inner ones. They arise from near the top on the sides of the stems; buds point upward but curve suddenly downward when the flowers open. They bloom at night.
Fruit: Smooth, red, juicy with persistent perianth remnant that withers slowly and dries attached to the end of the fruit. Flowers.
Remarks: These plants frequently produce monstrose crests, and crests occasionally produce normal shoots. The crested variety have spectacular blue marbled stems with pronounced sculpture effects.

Bibliography: Major references and further lectures.
1) Nathaniel Lord Britton, Joseph Nelson Rose “Cactaceae: Descriptions and Illustrations of Plants of the Cactus Family” vol. 2 The Carnegie Institution of Washington, Washington 1920
2) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
3) James Cullen, Sabina G. Knees, H. Suzanne Cubey "The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass" Cambridge University Press, 11/Aug/2011
4) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
5) Urs Eggli, Leonard E. Newton: “Etymological Dictionary of Succulent Plant Names” Birkhäuser 2004
6) Oakley, L. & Pin, A. 2013. Cereus spegazzinii. The IUCN Red List of Threatened Species 2013: e.T151795A562395. http://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T151795A562395.en. Downloaded on 15 July 2016.