Mammillaria (Mammillaria berkiana)

KingdomPlantae
PhylumTracheophyta
ClassMagnoliopsida
OrderCaryophyllales
FamilyCactaceae
GenusMammillaria (1)

Mammillaria berkiana is classified as Vulnerable (VU) on the IUCN Red List (1) and is listed on Appendix II of CITES (2).

Mammillaria berkiana is a stout, rounded cactus which is endemic to a small area of Mexico (1) (3) (4). The genus Mammillaria is one of the largest of the cactus family, comprising nearly 200 recognised species. The scientific name for the genus is derived from the Latin word ‘mammilla’, meaning ‘nipple’ or ‘teat’, and refers to the protruding tubercles which are characteristic of Mammillaria species (5) (6). 

Mammillaria berkiana grows alone or in small clusters, sometimes with up to 40 stems (3) (4). The stems are generally olive-green to dark green (4). Spines originate from the ends of the tubercles, which are arranged in angled, spiralling rows (6). The widely-spread radial spines are white, fine, and needle-like, while the central spines are straight and reddish-brown, with white at the base (3) (4). The axils (the area between each tubercle) generally lack bristles, but may occasionally be slightly woolly (3) (4) (5).

Mammillaria berkiana has small, deep-set, bell-shaped flowers which are dark purple-pink and have purple stigmas. The fruit of this species is club-shaped and whitish-pink, with black seeds (3) (4).

Some confusion exists around the taxonomic status of Mammillaria berkiana, with some sources considering it to be the same species as Mammillaria mercadensis. There is very little that differentiates the two species apart from the intensity of the flower colour (1).

Endemic to Mexico, Mammillaria berkiana occurs in two sites north of San Andreas which, due to their close proximity, are considered a single location (1). It occurs at elevations from about 1,600 metres up to 2,400 metres (1) (3) (4).

Occurring in semi-desert habitat, Mammillaria berkiana is a primarily cliff-dwelling species, inhabiting areas of sloping volcanic rocky terrain (1) (4).

Very little specific information is available on the biology of Mammillaria berkiana. It flowers in late autumn to early spring, with individual flowers remaining open for around five or six days (4). 

Mammillaria berkiana is a member of the Cactaceae, or cactus family. In general, cacti have evolved to cope with hot or arid environments. The thick, succulent stems have a large volume to store food and water, and are usually covered in a thick, waxy layer which helps to prevent water loss (7). The spines present on most cacti are essentially modified leaves, which grow from a unique, specialised structure called an areole. The areole is a sunken cushion of tissue which has two buds (growing points), with spines developing on one, and flowers and fruit on the other (7) (8) (9).

The spines of cacti protect the plant from grazing animals, and light-coloured or woolly spines reflect the sunlight, preventing damage from the sun’s radiation. Water also accumulates on the spines of cacti during the night or when it rains, and is then directed down the stem to the roots. The roots of cacti are generally shallow and widespread, allowing them to exploit temporary water sources at the surface. Many species, including Mammillaria berkiana, have taproots that go deep into the soil, anchoring the plant and enabling it to obtain additional water and nutrients (7).

The major threats to cacti in general include agricultural development and deforestation, urbanisation, and infrastructure development, such as road building, hydroelectric dam projects and mining. Collection of cacti for the wild for specialist collectors or the horticulture trade also poses a threat to many species (10) (11).

A further threat to cacti species, including Mammillaria berkiana, is climate change. Climate change may affect species physiology, flowering times and interactions with other species, for example with key pollinators (10) (12). As a consequence, shifts in geographic distributions may occur. This is of particular concern for species which already have a restricted range, such as Mammillaria berkiana (1).

Mammillaria berkiana is listed on Appendix II of CITES, meaning that international trade in this species should be carefully regulated (1) (2). Mexico has made major progress in succulent plantconservation activities, with existing lawsbeing more effectively enforced. Scientists are also activelyengaged in research related to cactus conservation. Illegal collecting and the unnecessary destruction of plants have been greatly reduced in recent years, but the decline of many succulent plant populations still continues (11).

The IUCN/SSC Cactus and Succulent Plant Specialist Group have recommended that sustained conservation efforts should be coordinated on a broad front to prevent further extinctions. As far as possible, local inhabitants and communities need to be involved in conservation planning to ensure full support for conservation decisions (11). Efforts for the conservation of cacti should be concentrated within the present and future distribution pattern of the species (12).

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This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

  1. IUCN Red List (August, 2013)
    http://www.iucnredlist.org
  2. CITES (May, 2011)
    http://www.cites.org
  3. Mammillarias.net - Mammillaria berkiana (May, 2011)
    http://www.mammillarias.net/gallery/mammillaria_species.php?searchstring=berkiana&lg=uk
  4. Cactuspedia - Mammillaria berkiana (May, 2011)
    http://www.cactuspedia.info/schede/MAMMILLARIA/Mammillaria_berkiana/Mammillaria_berkiana/Mammillaria_berkiana.htm
  5. Cactus Guide – Mammillaria (May, 2011)
    http://cactiguide.com/cactus/?genus=Mammillaria
  6. San Antonio Cactus and Xerophyte Society - Mammillaria (May, 2011)
    http://sacxs.org/Inside_the_Club/Horticulture/Mammillaria.pdf
  7. Dalhousie Collection of Cacti and other Succulents: Biology of Cacti (February, 2011)

    http://cactus.biology.dal.ca/biology.html
  8. Cactus and Succulent Society of New Zealand (February, 2011)

    http://www.cssnz.org/
  9. Heywood, V.H. (1978) Flowering Plants of the World. Oxford University Press, Oxford.
  10. WWF – Cacti (May, 2011)
    http://wwf.panda.org/what_we_do/endangered_species/cacti/
  11. Oldfield, S. (1997) Cactus and Succulent Plants - Status Survey and Conservation Action Plan. IUCN/SSC Cactus and Succulent Specialist Group. IUCN, Gland, Switzerland and Cambridge, UK.
  12. Téllez-Valdéz, O. and Dávila-Aranda, P. (2003) Protected Areas and climate change: A case study of the cacti in the Tehuacán-Cuicatlán Biosphere Reserve, México. Conservation Biology, 17(3): 846–853.