Pterocactus

A lot of people are put off growing Pterocactus since their first contact with them is Pterocactus tuberosus (syn. P. kuntzei) which tends to shed many of its thin joints in the winter. It does this in habitat in the resting season, relying on its underground tuberous root for regeneration the next season. In fact, it can be promoted to flower by removing much of the previous year’s growth when it immediately puts up new growth and flowers.

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If most of last year’s top growth is left on (providing it does not fall off of its own accord) it often does not flower the following year. However, I did an experiment once where I left the top growth on for about three years and it got rather bushy, but then started to flower freely again. When it does bloom it has really attractive flowers coming from its spindly stems.

This species is quite easy to propagate as often branches fall off and it is usually easy to get hold of a start, but when rooting them they can often stand still for a year or two since they need to grow the underground storage root before producing much top growth.

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A few more species of Pterocactus are now becoming available, but few are really show plants since their top growth, although thicker than P. tuberosus tends to sprawl, and unlike most cacti when they bloom the flowers are terminal on the stems. This means when the flower or fruit drops off it leaves a cavity in the stem end so that stem cannot grow any further and needs to put out a new stem or flower below where the previous flower was.

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They also have an unfortunate habit of some of their stem tips drying up, but as mentioned, in habitat most of the above ground growth can often be lost in the resting season so stems are renewed. I have not found them hard to grow but they prefer a cool winter rest. They are really for those with a botanical interest in the plants themselves rather than contenders for the show bench.

Photos and text by Dave Whiteley

 

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