Turbinicarpus (Turbinicarpus alonsoi)
|Size||Diameter: up to 9 cm (2)|
Classified as Critically Endangered (CR) on the IUCN Red List (1) and listed on Appendix I of CITES (3).
Turbinicarpus alonsoi is a small cactus with a single, flattened stem, divided into angled projections known as tubercles. Each tubercle measure up to 1.5 centimetres long and is glaucous (bluish-grey) to grey-green in colour. The areoles of this species bear a reddish-brown ‘wool’, which turns grey with age, and three to five flattened, cardboard-like spines, which measure up to two centimetres long and are irregularly curved inwards. The spines are grey in colour, with darker tips. The flowers of Turbinicarpus alonsoi are borne in the centre of the stem, measure up to three centimetres in diameter, and are rose-magenta in colour (2).
This species somewhat resembles the artichoke cactus, Obregonia denegrii, but the tubercles of the latter are ascending or pressed closely to the stem. It is also similar in appearance to Ariocarpus retusus, which lacks spines, and can be distinguished from the many forms of Turbinicarpus schmiedickeanus by its larger stems and tubercles, and by the magenta flowers (2).
Endemic to the state of Guanajuato, Mexico, where five small populations have been found in a limited area of just two square kilometres (2).
Turbinicarpus alonsoi grows on shaly canyon walls, with sparse vegetation, at an altitude of 1,100 metres above sea level (2).
The area in which this species grow is very hot, with daytime temperatures that can reach 43 degrees Celsius in the shade. In shaded positions, the plants can attain very large sizes, and specimens up to 15 centimetres in diameter have been recorded. Turbinicarpus alonsoi flowers from March to October, and the mature fruits, which measure around one centimetre long, contain about 100 black seeds (4). The fruits are reddish at first, later becoming dry and dehiscent, developing one or two longitudinal slits through which the seeds, which measure 0.1 centimetres in length, are released. The dehiscence of the fruit is a distinguishing feature of the Turbinicarpus genus (2).
Illegal collection is the main threat to Turbinicarpus alonsoi (1). At the time of its discovery it was one of the most sought-after cacti. Artificial propagation in high numbers made it quickly available to collectors, although wild plants and possibly seeds were still exported illegally from Mexico. Nowadays, plants, seedlings and seeds of cultivated origin are quite common, but wild populations have suffered significantly from illegal collection, with the plants having drastically diminished in number at the more accessible sites near the road (5). The wild population is currently estimated at around 5,000 individuals, restricted to just one tiny area, and its numbers have more than halved since the species’ discovery (1).
Turbinicarpus alonsoi is listed on Appendix I of the Convention on International Trade in Endangered Species (CITES), which includes species threatened with extinction, which are or may be affected by trade. Trade in this species should be subject to particularly strict regulation in order not to further endanger its survival, and must only be authorized in exceptional circumstances (3).
To find out more about Turbinicarpus species see:
The Turbinicarpus Information Exchange:
Information supplied and authenticated (12/08/2010) by Alessandro Mosco, PhD, Department of Life Sciences, University of Trieste.
- Areole: in cacti, the felted or woolly, cushion-like structures from which spines grow, flowers develop and new stems arise.
- Dehiscence: opening or splitting along a line to discharge the contents.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Genus: a category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
- Tubercle: in cacti, a conical or angular swelling upon the stem.
IUCN Red List (August, 2010)
- Glass, C.E. (1998) Identification Guide to Threatened Cacti of Mexico. Fideicomiso Fondo para la Biodiversidad, Mexico.
CITES (August, 2010)
- Zachar, M. (2004) The Genus Turbinicarpus. Vydavatel’stvo Igor Drab & Spolocnost’ Cactaceae etc., Bratislava.
- Lüthy, J.M. (2001) The Cacti of CITES Appendix I. Bundesamt für Veterinärwesen, Bern.