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Tony Roberts

With the advent of the more “in vogue” Tephrocactus such as T. bonnieae and certain forms of T. alexanderi and T. molinensis, it is perhaps not surprising that plants of T. articulatus are rather neglected in our collections and linger at the back of the staging. In this article I hope to bring this species in its various forms to your attention once more, so that you can see these plants as ones well worth growing.

Lots of names have come and gone (or nearly gone!) over the last 175 years for plants which are now all attributable to Tephrocactus articulatus, starting with Cereus articulatus (1837), Cereus syringacanthus (1837), Opuntia diademata (1838) and Opuntia turpinii (1838), then later on Opuntia papyracantha (1898) and Opuntia strombiliformis (1929). It is still useful today to use some of these specific or varietal names to describe plants in cultivation, that vary typically in the body shape and colour and particularly in the degree of spination. This is despite the fact (as Mike Partridge tells me) that driving along a road in Argentina you might see many of these variants within a short distance or even in a single population. So to illustrate this point, I’ll pick out a few different clones of T. articulatus within my collection.

Tephrocactus articulatus (free-flowering form)

This is the plant I have always called T. articulatus sensu stricto. It has relatively small segments compared with most other forms, each one being 4-5cm long and quite slender, and has a sparse number of flat central spines (just one or two) coming from the top-most areoles (fig. 1). Once it gets to the size shown, it is quite slow growing, just the one new segment on the far left in the last year. This is because it seems to put all its energy into flowering for, compared to all the subsequent forms, it is very free-flowering. The floral remains are quite persistent and may stay well attached for several years. This plant has produced numerous flowers over several summers; the flowers are pure white and about 3-4cm across (fig. 2) although I also have a very similar plant which has whitish flowers with a pale pink hue.

Fig. 1

Fig. 1. Tephrocactus articulatus (free flowering form)

Fig. 2

Fig. 2. Tephrocactus articulatus (in flower)

Tephrocactus articulatus (papyracanthus with white spines)

Opuntia papyracantha and O. diademata are the names I originally associated with this next clone. It has several distinguishing features, segments 5-8cm long (or even longer) and more rounded than the previous clone, and several white papery spines on each of the upper areoles, making for a handsome plant. I have several plants of this clone; some are quite tight clumps whilst another has grown several “branches” of segments (fig. 3). This plant has stayed intact (is depicted in a 19cm pot) and several of the branches are now 9-10 segments long. As I’m sure many of you know, this is the type of plant which will fall apart quite easily, especially if it gets too dry in winter. The plant may look as one but after the first watering of the spring or when you move it, you notice that segments are actually detached; this is the result (fig. 4)! The saving grace here is that you now have plenty of segments from which to propagate new plants. Put 28 of them in a seed tray, half buried in the compost and they will soon root – before you know it you have a forest of new plants (fig. 5), all waiting to be put into separate pots. Being a plant that propagates so readily from detached segments, it must have it in its genes that it doesn’t need to flower and set seed to survive, for I am still waiting after many years.

Fig. 3

Fig. 3. Tephrocactus articulatus (papyracanthus) – with white spines

Fig. 4

Fig. 4. Tephrocactus articulatus (papyracanthus) – segments

Fig. 5

Fig. 5. Tephrocactus articulatus (papyracanthus) – new plants in seed tray

Tephrocactus articulatus (papyracanthus with dark spines)

More rarely in cultivation, you see a clone of Tephrocactus articulatus (papyracanthus) which has even larger segments (8-12cm long) bearing more distinctive and wider papery spines which are dark brown or even black in colour. I have seen plants like this called T. turpinii but I’m not certain whether this matches the original description. It also has a propensity to detach segments so my plants of this clone don’t normally reach more than four segments tall (fig. 6). It is also shy to flower but this summer (2012) for my first time it did so producing two flowers one after the other (fig. 7); again the typical white flower you would expect for T. articulatus.

Fig. 6

Fig. 6. Tephrocactus articulatus (papyracanthus) – with dark spines

Fig. 7

Fig. 7. Tephrocactus articulatus (papyracanthus) – with dark spines, in flower

Tephrocactus articulatus (inermis and strombiliformis)

Finally, there are two forms that have no central spines at all (or perhaps just a very occasional one). These I have separated as inermis and strombiliformis although these names are sometimes used synonymously. The plant which I grow as T. articulatus (inermis) has pale green chunky, cylindrical segments (5-7cm) which are well attached to each other resulting in a quite robust and stocky plant (fig. 8). In contrast, T articulatus (strombiliformis) has segments which are more like an ellipsoid in shape and are more blue-grey in colour. Sometimes with this form, the segments are rather indeterminate and a considerably longer column results. It forms a plant of similar size to T. articulatus (inermis) but rather than illustrate this, I show you one of my propagation experiments (fig. 9). Here, I have taken a single segment of this clone, sliced it in half vertically, and then grafted each half horizontally onto a stock of O. elata. Very quickly new segments are produced which can be removed every few months and rooted down as new plants – a somewhat quicker method I find than taking segments from a plant on its own roots.

Fig. 8

Fig. 8. Tephrocactus articulatus (inermis)

Fig. 9

Fig. 9. Tephrocactus articulatus (strombiliformis)

I hope this article and the photographs have helped you to see what some people may consider a rather ordinary plant, Tephrocactus articulatus, in a new light.

This article was originally published in Tephrocactus Study Group (the 'TSG Journal'), June 2012, Vol. 18, No. 2, pages 17-24. © TSG and Tony Roberts. It is reproduced here with the permission of the author.