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To illustrate the variability of shape within the genus Echinocereus I have chosen a stick-like plant which, unless flowering is very difficult to find in habitat. Oddly enough my first discovery was unplanned as I was looking for Echinocereus papillosus, which tends to grow close to the ground. In habitat Echinocereus poselgeri is one of several taxa in the Wilcoxia group most of which share the habit of growing up through other shrubs. The thin stems can easily reach a length of a metre or more and are well-camouflaged amongst what is referred to in South Texas as ‘thorn-scrub’. As the name of this habitat implies reaching the plants to obtain good images can be problematic.

 0319 Fig1 E.poselgeri thorn scrub

Fig. 1 E. poselgeri in thorn scrub, Starr County, Texas (photo Peter Berresford)

Echinocereus poselgeri, and its fellow wilcoxias all produce tuberous roots. With the exception of the ‘woolly’ Echinocereus schmollii, the stems are armoured with sharp radial spines and Echinocereus poselgeri, also has a longer upward pointing central spine. While other wilcoxias are quite localised in Mexico, our plant of the month ranges over much of the north-west of the country. In the US it is the only Wilcoxia growing along the Rio Grande from Webb County almost as far as the Gulf coast and has acquired the name of ‘Dahlia hedgehog cactus’ after its root structure. Finding this plant above about 500 metres is extremely unlikely.

0319 Fig.2 E poselgeri2

Fig. 2 Left: Vicious Acacia thorns protect the opening flower of E. poselgeri, Nuevo Leon, Mexico 2015 (photo Peter Berresford)

One would think that a plant from low altitude growing in a warm climate would be adverse to cold in the UK but in fact this can tolerate dry temperatures over winter of –5°C. Why would you want to grow a stick, I hear you ask? The genus should give you the clue that this is a highly floriferous cactus, often producing more than one 5–7cm dark-throated pinkish purple bloom from near to the end of each stem. The trick to many flowers is to treat this plant like a rosebush and each year give it a good prune. This will reward you by producing several stems from the cut, each of which will produce flowers while young. The cut pieces of stem should also produce new plants which will root down.

0319 Fig3 E.poselgeri David Park

Fig. 3 E. poselgeri ERC 581 grown by David Parker (photo David Parker)

Peter Berresford

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