About the genus
Aylostera form a genus of small- growing cacti from the high Andes, mostly from southern Bolivia, with a few from northern Argentina. In nature they rarely exceed the size of a golf ball; the flowers are relatively small, perhaps 2–4cm across.
Due to the similarity of appearance of both the plant bodies and the flowers Aylostera was thought, for many years, to belong to the genus Rebutia. Indeed, they are often still found for sale as Rebutia. DNA research has shown, however, that these two genera are only distantly related (as distant as to Gymnocalycium or Echinopsis, for example). Thus, if you want to be scientifically accurate, you should stop using the name Rebutia for plants in the genus Aylostera.
There are two subgenera, Aylostera and Mediolobivia. Plants in the former are typically roughly spherical, or slightly flattened, often with dense spination. Plants in the latter tend to be ‘finger-shaped’, two or three times as tall as wide, and with shorter and sparser spination.
How to grow them
Aylostera are often considered to be beginners’ plants, as they are easy to grow. Notwithstanding this, they make excellent plants for any collection, as they are free- flowering.
In nature, they are often single- headed, and just produce one or two flowers at a time, while in cultivation they can readily form large clumps. As each head can have 10 or more flowers open at a time, a large bowl can be an impressive sight! It can be more of a challenge to keep them small and single-headed as they appear in nature.
Aylostera will grow in pretty much any free-draining compost suitable for cacti. However, the soil where they grow is typically quite acidic. If you want to make up your own compost to suit South American cacti in general, I would suggest that an ericaceous compost (sold as suitable for rhododendrons and azaleas) provides a better basis than general purpose compost. Mixing it with an equal amount of grit should help to keep it free-draining; most kinds of grit will do, but avoid limestone grit as this will reduce the acidity.
Watering follows the standard approach: from the start of April to the end of September, and keep dry in winter (or perhaps give them a little water once a month if in a warm room in the house). I add fertiliser at about ⅓ strength every time I water them; a fertiliser with trace elements ensures the plants get the minor elements they need. I use an ericaceous fertiliser, but again, any fertiliser suitable for house plants will do.
As they come from high altitudes, they grow better in strong light, and they are tolerant of cool temperatures in winter. Mine are in an unheated greenhouse (although I live near the sea, so frosts are usually not severe or long lasting). It is said they flower better if kept cold in winter, although I find them to be pretty much free-flowering anyway.
Finally, they are easy to propagate, and can flower in the second year from seed. In early summer, heads can be carefully removed from a clump, and after being left for a few days for the wound to heal, will readily root up to form new plants.
Text Ralph Martin; photos Xiaoqing Li
No part of this article may be reproduced without permission. Copyright BCSS and the Author 2021