About the National Collection

A word about names

For a simplistic explanation of taxonomy as regards cacti and why we choose the names we do, click here.

The family Cactaceae is a group of plants which is undergoing a rapid evolutionary radiation. This means that plants are adapting to their various environments rapidly (in evolutionary terms), and new species are in the process of forming. It is often very difficult to decide what is a different species from another when there is a gradual change in appearance from one to the other over a geographical area. On top of this, new plants and varieties are being discovered all the time, as each new remote valley of the Andes is explored by botanists.

With the genera Aylostera, Rebutia and Weingartia, there has been a great deal of argument as to which plants were related to which others, and as a result much argument about what individual plants should be called, and whether or not plants are full species, subspecies, or just varieties of others. Here at this collection we have adopted, for the moment, two recent studies which have compared the features and the DNA of currently known plants, backed up by extensive fieldwork. These studies (one for Aylostera and Rebutia, including Mediolobivia, and one for Weingartia, including Sulcorebutia and Cintia) have been relatively well received by the establishment and give us a good framework to base our labelling and cataloguing. We will of course try to keep up to date with any new studies that are produced.

Some external resources:

Stanislav Šuba’s comparative database of field numbers

Ralph Martin’s field number database

Claude Bourleau’s Sulcopassion website

A word about numbers

The concept of “species” is difficult to use with these plants, which are undergoing evolutionary diversification. Many of the plants in this collection come from small isolated populations in valleys or other isolated parts of the mountains.

Plants can vary through a cline in a geographical area, where they may be thought of as two separate species at either end of the cline, but at no point in between.

Then there are the arguments between taxonomists as to what characteristics warrant the giving of separate names.

A way around all this confusion is to give each plant a field collection number, which, if done properly, will refer back to a database of where and when the original plant was located, and who found it. Then, regardless of what name the plant is given, we should at least be able to trace the geographical location where it grows naturally. Problems with this may include the original collectors not being very precise, and plants being propagated without care to avoid cross-fertilisation and the offspring being given the same field number.

Nearly all of the plants in the National Collection have field collection numbers and we always try to acquire plants from respectable sources, where propagation has been from cuttings, or if from seed, carried out in isolation and very carefully.

The label shown above shows two numbers: one of them is our own reference number (all plants have their own number) and the other is the field collection number, in this case WR521a.

Scientific References

Taxonomy of Aylostera, Rebutia & Weingartia

The studies we use are: Hentzschel, G. & Augustin, K. (2008). Weingartia, Sulcorebutia und Cintia, eine untrennbare Einheit (an indivisible unit) – Teil 2: Merkmalsvergleiche und Neukombinationen (Part 2: feature comparisons and recombinations). Gymnocalycium 21(2): 767-782 Mosti, S., Bandara, N. L. & Papini, A. (2011). Further insights and new combinations in Aylostera (Cactaceae) based on molecular and morphological data. Pak. J. Bot. 43(6): 2769-2785

There is also a more recent study by Ritz et al. (2016) on the taxonomy of Aylostera, which we have not adopted (but may do in the future). This study also looked at DNA and their results recommend only nine species (i.e. “lumping” several together). This study is:

Ritz, C. M., Fickenscher, K., Foller, J., Hermann, K., Mecklenburg, R. & Wahl, R., (2016). Molecular phylogenetic relationships of the Andean genus Aylostera Speg. (Cactaceae, Trichocereeae), a new classification and a morphological identification key. Plant Syst Evol (2016) 302:763–780