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).