Echinocereus (2002)

By Leo Martin (June 2002)

Echinocereus, which means “spiny candle,” was described by Georg Englemann in 1848. Our local (Leo lives in Arizona) Echinocereus engelmannii is named after him. These hedgehog cacti are popular in cultivation for their large, beautiful flowers, spectacular stems and spines, and often easy culture.

Many form large clumps, but some cluster only sparingly and some are solitary. All flower in the spring to early summer with big, showy, mostly satiny flowers in yellow, green, brown, pink or purple.

E. triglochidiatus has heavy, waxy flowers of orange or red. The pistil at Echinocereus flowers’ center is almost always green. Unique to the genus, emerging flower buds tear through the plant’s skin above an areole, leaving a scar after fading, rather than arising from areoles or axils between areoles as in other cacti.

All come from predominantly summer-rainfall areas and tend to be found in fully exposed, dry microclimates such as vertical rock faces, slopes of scree or arid flats. Root systems are smaller than in some other cacti.

These are hints for successful culture: shallow, fast-draining mineral soil without organics, full sun, no winter water and a drying out between waterings in the summer. Periods of most active growth are late winter through early spring and fall through early winter. Many rest during the hottest part of the year and don’t need much watering.

Echinocereus pectinatus var. rigidissimus, the Arizona rainbow cactus, grew throughout the Valley of the Sun and east to Superior before cattle were introduced by Europeans. Central and southern Arizona was then covered by grasslands rather than desert, and all the washes were perennial streams.

The rainbow needs more summer water than most other species. It lacks the beautiful pink and purple spines when grown in less than full sun or when planted in soils containing much organic material.

Other popular species are E. dasyacanthus, with mostly solitary stems and large, up-facing flowers; E. engelmannii, a confirmed clumper with long spines and pink flowers; E. pentalophus, a profuse clumper with long, narrow stems and huge magenta flowers that look as good as a ground cover or a hanging basket; and E. pulchella, with its greyish-green solitary body, small spines and huge pink flowers.