Accepted Scientific Name: Opuntia macrorhiza subs. pottsii (Salm-Dyck) U.Guzmán & Mandujano
Cactaceae Syst. Init. 16: 18 18 2003.
Opuntia macrorhiza var. pottsii (Opuntia macrorhiza subs. pottsii) Photo by: Cactus Art
Plant collector by David Van Langen, Locality: Near Midland Texas USA. Notes: Plants from this population have long tuberous roots and are covered in spines, they are really very nice!! they are very cold hardy and stays fairly small and compact.
Origin and Habitat: Widespread In Midwest and south-western United States (Colorado, Utah, Wyoming, South Dakota, Nebraska, and Missouri) and northern Mexico (Chihuahua and probably also in the state of Sonora as there is suitable habitat). The population is very scattered but it is locally common.
Altitude range: This species grows at an elevation of 800 to 2200 metres above sea level.
Habitat: Grows on loam or rocky, sandy places, alluvial hillsides and plains, in desert scrubs and grasslands (mesquite and yucca grassland). Opuntia pottsiiSN|19900]]SN|19900]] has a wide range, and although a cryptic species it is probably reasonably common and resistant to most threats as it has underground tubers. There are no significant threats to this species although some areas would have been impacted by agricultural activities and there may be some localized declines.
Synonyms:
See all synonyms of Opuntia macrorhiza
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Accepted name in llifle Database:Opuntia macrorhiza Engelm.Boston J. Nat. Hist. 6: 206. 1850Synonymy: 12
Accepted name in llifle Database:Opuntia macrorhiza subs. potosina (Hern.-Valencia) U.Guzmán & MandujanoCactaceae Syst. Init. 16: 18 18 2003.Synonymy: 2
Accepted name in llifle Database:Opuntia macrorhiza subs. pottsii (Salm-Dyck) U.Guzmán & MandujanoCactaceae Syst. Init. 16: 18 18 2003.Synonymy: 11
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Common Names include:
ENGLISH: Potts prickly pear, Potts pricklypear cactus
Description: Opuntia pottsiiSN|19900]]SN|19900]] (Opuntia macrorhizaSN|19900]]SN|19886]] subs. pottsii) is a diminutive shrubby plant up to 12(-30) cm tall, forming low prostrate clumps up to 2 metres in diameter. It is a cryptic species and grows from a tuberous root. The pads are glaucous blue-green when healthy. The usually 1-3 grey-white spines per areole are produced only on the upper part of the pads. Throughout it range the flowers may be red, magenta, pink, orange, yellow, white, and combination of these colours are found, sometime toghether in the same populations. When yellow, the flowers often have red centres. Two varieties of Opuntia pottsiiSN|19886]]SN|19900]]are recognized by David J. Ferguson (2012), the nominate form var. pottsii and var. montana. Varieties intergrade where they meet.
Derivation of specific name: The species was named after John Potts, who managed the mint in Chihuahua, Mexico, collected the original material of the species, and between the years 1842 and 185o sent many cactus collections to E Scheer at the Royal Botanic Gardens, Kew, England (Britton and Rose, 1919-13).
Stem: Segments usually not rooting when touching, round to obovate, often narrowed near base (stipitate), upright, glaucous blue-green (Yellow-green or purplish when stressed), 5-10(-13) cm long, 5-8(-10) cm wide, to 1.2 cm thick, wrinkled under very dry or cold conditions. Commonly plants produces only 6-10 pads and often a short trunklet.
Roots: Rhizomes commonly present. Central root tuber usually long and roughly cylindrical.
Areoles: 10-16 mm apart, narrowly obovate to nearly circular, 2-3 mm across.
Glochids: Yellow or brown, to 3(-5) mm long, numerous in a tight tuft.
Spines: One to five spines from the upper areoles, 1.5 to 6.5 cm long, whitish, grey or brownish, and black speckled, acicular or somewhat flattened, often rwisted, and downwards pointing. In each areole one spines is longer, while the other are short or different length. Rarely plants of Opuntia pottsiiSN|19900]]SN|19900]] are spineless.
Leaves: Ephemeral, usually green or reddish only 3-5 mm long.
Roots: It has a single or branched fleshy, enlarged taproot that exude a milky sap when injured. It may be smooth or costricted at the neck.
Flower: Usually orange, pink, yellow with red bases to reddish, appear on early June , 5-6(-9) cm long and 4-5(-6) cm in diameter with petals curving upward and rolled back at sides.. In some flowers the slender pericarpel alone often 5 cm long. Filaments 12-15 mm long, yellow, greenish or purplish. Anthers yellow up to 2 mm long. Style pinkish 17-23 mm long. Stigma lobes 5-8 cream coloured, stout 3-4 mm long. Pericarpel smooth with few small areoles with white hairs and yellow-brown glochids. Flowers open about mid-day and close by 4:30 P.M., and do not open again.
Blooming season (in habitat): late April to early June. Most plants tend to produce flowers at much the same time, and the flowers may be finished in about one week.
Fruit: Obovoid narrow with slender base, and smooth, greenish to pinkish or reddish purple at maturity, fleshy, juicy, 2.5-4 cm long, 2.5-3cm in diameter flattened and irregular. The pulp is pale greenish and not very sweet. Fruits mature in 2.5-5 (or even more) months.
Seeds: Thick discoid, irregular in outline, wide margined, and beaked at the hilum, tan to grey, 3.5-5.5 mm in diameter.
Subspecies, varieties, forms and cultivars of plants belonging to the Opuntia macrorhiza group
- Opuntia macrorhiza Engelm.: has only moderately glaucous stem segments that may reach 10 cm in length and diameter and basically yellow flowers.
- Opuntia macrorhiza subs. potosina (Hern.-Valencia) U.Guzmán & Mandujano
Opuntia macrorhiza subs. pottsii (Salm-Dyck) U.Guzmán & Mandujano: has very glaucous compact stem segments reaching 5-6 cm in length and diameter, longer than wide, and distinctly stipitate. It is easily distinguished from other varieties of O. macrorhiza by its red flowers (as opposed to yellow), and very slender spines.- Opuntia pottsii var. montana n.n.: (subsp. pottsii) Joints mostly wider than long. Spines usually white. Fruit mostly chunky and short, usually pinkish. Distribution: Areas of conifer or oak woodland above 1,800 m, occasional in grasslands at lower elevations.
Bibliography: Major references and further lectures
1) Pinkava, D.J., Baker, M. & Puente, R. 2013. Opuntia pottsii. The IUCN Red List of Threatened Species. Version 2015.1. <www.iucnredlist.org>. Downloaded on 21 June 2015.
2) N. L. Britton, J. N. Rose: “The Cactaceae. Descriptions and Illustrations of Plants of the Cactus Family.” Vol I, The Carnegie Institution of Washington, Washington 1919
3) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
4) A. Michael Powell, James F. Weedin “Cacti of the Trans-Pecos & Adjacent Areas” Texas Tech University Press, 2004
5) David J. Ferguson “Keys to the identity of cacti of the Albuquerque & Santa Fe area (Bernalillo, Sandoval, Santa Fe, Socorro, Torrance, and Valencia Counties)” November 1993 (updated May18, 2012)
Cultivation and Propagation: Opuntia pottsiiSN|19900]]SN|19900]] is a relatively difficult to grow so it is seldom cultivated for the horticultural trade.
Soil: Requires a sandy or very well-drained soil. Prefers a neutral to alkaline soil.
Moisture: Plants must be kept rather dry in the winter but they like a reasonable supply of water in the growing season. A position at the base of a south-facing wall or somewhere that can be protected from winter rain is best for this plant. Plants endure considerable abandon.
Exposure Requires plenty of sun.
Hardiness: Is is quite cold tolerant plant, it can succeed outdoors.
