Whether you think they are Rebutia, Sulcorebutia or Weingartia, the sulcos are a deservedly popular group of plants and one or two are frequently encountered in collections and at shows.
Rebutia tiraquensis was described from Carrasco Province in Bolivia by Martín Cárdenas in 1957, making it one of the earliest reported. Despite this, it is rarer in collections than many of the more recent discoveries, perhaps due to its tendency to remain solitary or, at least, to produce offsets only sparingly (a few forms excepted).
Fig. 1 Rebutia tiraquensis ‘Krahnii’ WK279 (lef) Rebutia tiraquensis ‘Oenantha’ HS 21 (right)
As with other sulcos, plants are very variable in spine length, arangement and colour; flowers can be pink, red, orange or yellow, and sometimes bear a slightly paler throat giving a subtle bicoloured effect. This has resulted in many names and I would suggest that any plants encountered under the names polymorpha, lepida, aguilarii, totorensis, renatae, krahnii (Fig. 1), oenantha (Fig. 1), pampagrandensis, augustinii, heinzii (Fig. 2), mariana (Fig. 2), electracantha, aglaia (Fig. 2), or bicolorispina n.n. are probably this species.
Fig. 2 Rebutia tiraquensis ‘Heinzii’ HS 151 (left) Rebutia tiraquensis ‘Mariana’ HS 15 (centre) Rebutia tiraquensis ‘Aglaia’ KK 809 (right)
Rebutia tiraquensis is no more demanding in cultivation than any other sulco and benefits from good light and regular watering during the growing season. Like many Andean plants, it is not used to the high temperatures encountered in our greenhouses and will slow or stop its growth during hot spells, especially if night-time temperatures cannot be brought down no matter how much ventilation is provided. Reduced watering during such times is often advised. I find that they tolerate the soil mix that I use for almost all of my other cacti and succulents so any mix that works well for you should do.
Fig. 3 Rebutia tiraquensis forms during winter
Seed of the different R. tiraquensis forms is available although it can be more expensive than that of most cacti since the fruits contain relatively few seeds. It tends to germinate only moderately well, which can be a blessing if you are prone to sowing many packets! I recommend keeping at least a pair of seedlings for a while – even from a single fruit the offspring can be quite variable and sometimes an individual plant stands out as being particularly handsome.
Phil Crewe
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