Ortegocactus macdougallii

Accepted name and Oaxaca

POWO accepts Ortegocactus macdougallii as the only species in the genus. Alexander published it in 1961. The older combination Neobesseya macdougallii and the newer Cochemiea macdougallii remain synonyms. Its natural range includes Oaxaca. The paper by Arellano-Perusquía and colleagues places it in a small area of San José Lachiguiri. [2-WWW] [2-WWW] [Arellano-Perusquía et al. 2013, POWO, checked on 11 October 2026. Arellano-Perusquía et al., p. 160]

In the 2023 phylogenomic analysis, the species formed a recognisable lineage within a larger group of mammillarioid cacti. The authors retained Ortegocactus separately from Cochemiea, citing structural and biogeographic differences. Its position in this group helps connect publications using different combinations of the name without multiplying descriptions of the same species. [Chincoya et al. 2023, Chincoya et al., pp. 13–15] [2-WWW]

Tubercles, flowers, fruits and seeds

Flat tubercles with a rhomboid outline cover the globose stem. In the dimorphic areoles, the upper part bears hairs and spines. The tubercle sometimes has a groove. There is one straight central spine. This structure combines a regular pattern on the stem surface with separation of the sites where spines and flowers are produced. [Vázquez-Sánchez 2012, Vázquez-Sánchez, doctoral thesis, January 2012, printed p. 89]

Flowers arise in the tubercle axils. They are yellow and radially symmetrical, with a length given in the description as 1.2–3 cm. The fruits are globose and dull red. The very small, rounded seeds are blackish-brown, with a pitted surface. [Vázquez-Sánchez 2012, Vázquez-Sánchez, doctoral thesis, January 2012, printed p. 89]

Stem and areole activity

The experiment used seven-year-old adult plants about 8 cm high. Tubercles including one to three areoles were cut from their young shoots, 0.5–1.5 cm long. An areole contains a meristem, a region of cells capable of dividing and forming new organs. When stimulated in culture, the meristem produced a lateral shoot, while additional adventitious shoot primordia formed on the surface outside the areoles. [Arellano-Perusquía et al. 2013, p. 161–163, ryc. 1]

Adventitious primordia appeared at the edges of the explant, at its base or between tubercles. Over the following weeks, they developed into organised shoots with small tubercles and an olive-green surface. Activation of the areole meristem and formation of a primordium outside an areole were distinguished by position and stereoscopic observations. [Arellano-Perusquía et al. 2013, p. 162–165]

Stock plants in the experimental greenhouse

The material came from a local nursery. Before cultures were initiated, plants were kept in a greenhouse for 12 months, at mean day and night temperatures of 30 and 20°C. The maximum photosynthetically active photon flux was about 1000 µmol m⁻² s⁻¹. A fertiliser described as 20–20–20 was applied once a month. The publication documents these conditions for preparing the stock plants. [Arellano-Perusquía et al. 2013, p. 161]

Shoot initiation and multiplication

The first stage used Murashige and Skoog medium, MS, with various combinations of NAA and BA. NAA is an auxin and BA a cytokinin. Treatments with NAA favoured callus formation, a proliferating wound tissue. New shoots were initially rare. In two treatments, after 116 days, four explants produced a total of 17 shoots through both areole activation and adventitious formation. [Arellano-Perusquía et al. 2013, p. 161–163]

A separate multiplication stage used a constant 4.4 µM NAA and three BA concentrations. After 110 days, the mean number of shoots per explant was 5.67 at 13.3 µM BA, 5.83 at 19.9 µM and 5.33 at 26.6 µM. Differences in shoot number were not statistically significant. At the lowest of these BA concentrations, however, shoots were longer, averaging 4.78 mm, compared with 3.93 and 3.67 mm in the other treatments. [Arellano-Perusquía et al. 2013, pp. 161, 163, Table 2]

At the two higher BA concentrations, the authors observed fasciated shoots, including cristata and monstrous forms. The result indicates a change in growth pattern under specific culture conditions. [Arellano-Perusquía et al. 2013, pp. 164–165]

Adventitious roots

Rooting was carried out on MS medium with half or one quarter of the usual mineral concentration. In the half-strength MS treatments, the auxin IBA was also compared at concentrations of 1.6 and 4.9 µM. After 50 days, the treatment with 4.9 µM IBA had about 75% rooted explants and a mean of 9.92 roots. On half-strength MS without a regulator, about 37.5% of fragments rooted. On quarter-strength MS without a regulator, about 58.3% rooted. [Arellano-Perusquía et al. 2013, pp. 161, 164, Table 4. The µM unit follows the methods, Table 4 incorrectly prints mM]

Root primordia were visible around day 30, and the roots elongated over the next 20 days. Their formation was not accompanied by callus formation. Rooted plants were the final stage of the experiment described. [Arellano-Perusquía et al. 2013, pp. 164–165]

Related articles

Materials from the author's archive

The species also appears in Konrad Szychowski's private material archive. [Rodríguez Ortega and Franco 2001, file p. 6]