Opuntiads of the USA

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Opuntia pulchella Engelm

(Micropuntia pulchella [Engelm] M.P. Griffith)
(Grusonia pulchella [Engelm.] H.Rob.]

Introduction

Opuntia pulchella is a little-grown cactus from the Great Basin. It is not commonly noticed because it is small and populations are widely disbursed. The species has had many names over the years. It may be best known for it's beautiful pink flowers.

Technical Description

Nomenclature:   Over time the opuntiads with club-shaped branches, or cylindrical branches, have been placed (and replaced) in various genera.  On various Web sites this plant has been referred to as Opuntia pygmaea, Micropuntia wiegandii, Opuntia tuberculosirhopalica, Micropuntia tuberculosirhopalica, Opuntia spectatissima, Opuntia barkleyana, Micropuntia spectatissima, Opuntia wiegandii, Micropuntia pygmaea, Micropuntia gracilicylindrica, Micropuntia brachyrhopalica, Micropuntia barkleyana, Corynopuntia pulchella, Opuntia pulchella, and Opuntia brachyrhopalica.  Apparently, Micropuntia pulchella (see article by Patrick Griffith) or Grusonia pulchella are currently accepted names.

Subshrubs: Plants may be small shrubs, very branching: The plants are technically evergreen, but like so many opuntiads can seem withered and dead out of their growing season.  Plants may be 5-10 inches across in the wild and a few inches tall, very branched.  Plants have enlarged underground roots; sometimes 4 inches across.  The plants are mostly found in Nevada, but are also reported from adjacent areas of central Utah and  Southern California (west of Mt. Charleston). 

Cladodes:  Shape  varies but is typically cylindrical, or club-shaped, 1-3 inches and perhaps ½ inch in diameter (often less than ½ inch), visibly tuberculate. 

Glochids:  brown or tan, up to ¼ inch long (approx.), often rust-red or dark straw-colored.  , in tufts, densely packed, brown, red-brown or tan, typically 3-4(5) mm, brown with age.

Spines: numerous (especially at distal ends of branches), sometimes 6 per areole but more than a dozen can be found in some areoles, longer spines can be as long as some branches (over 2 inches long).

Flowers: rose-pink or purple (especially inner tepals), or flowers may be white, tepals ½ to 1-inch in length.  

Fruits: 20 to 40 mm long, 12-20 mm wide, elongate with stipitate base, reddish or green-red when mature, fleshy.

An article contributed by Charles W. Barnum, Photographs and Text © September 14, 2005

Introduction

Grusonia pulchella is a little-known cactus shrub, often called sand club-cholla or Opuntia pulchella. The short, fleshy segments are clumpy in appearance. The spines can be either short and hair-like, or long and needle-like on the same plant. 

The plant blends in so well with the environment that one might walk by without seeing it. There are green versions and red versions, but such variation might simply be color phases due to age or environmental influences. Each plant has a tuber that stores moisture. Some plants have more than one tuber that will split off into multiple plants.

This cactus grows almost exclusively in Nevada, but it also occurs in Utah. A few may be found in California along the state line with Nevada.

Environment

This attractive cactus forms small clumps in the dry regions of Nevada usually about 4,000 feet in elevation. It grows on slopes where rainwater drains. It is also found near dry lakes and streambeds. The reason it grows in these areas is clear from a look at the yearly rainfall.

The average rainfall around Silver Springs and Fallon, an area where they grow, is about 5” a year. Most of the precipitation occurs in the spring and the fall but also in the winter. I don’t believe 5” is sufficient moisture to sustain a Grusonia pulchella. That is why they grow where water accumulates for short periods after rain in drainage areas and along dry ponds and streambeds.

I believe that Grusonia pulchella is on the decline.  This area may be in a very long drought (thousands of years) as evidenced by ancient dry lakes and dry rivers that abound. It’s easy to speculate that Grusonia pulchella was more widely distributed thousands of years ago, but it has now retreated to the few areas where it can obtain sufficient moisture to survive.

Temperatures

Grusonia pulchella can tolerate a wide range of temperatures. Winter temperatures may drop to minus 10°F. Summer temperatures in the same area can exceed 110 °F. Day to night temperatures varies widely.

Soil

Grusonia pulchella will grow in a wide range of soils from sandy soils to loam. Dry soil around the roots in its environment can be brick-like. Soil pH is about 6.0 in its native range. Adding bone meal to potting mixes is an excellent method to maintain a PH near 6.0. I use 50% sandy loam and 50% cactus potting mix to pot G. pulchella cuttings.

Propagation

Grusonia pulchella will propagate by seed when sufficient moisture is present. It will also propagate by natural division or clumping. The plants have only a few roots. They do have a large tuber.

In cultivation, it is easy to propagate cuttings. The best time to take cuttings is in the spring and fall. After cutting, let the wound dry for a week. Then paint the scar with pruning sealer. You may either plant it in moist sandy soil or stand it upright in dry pumice for further drying before planting (up to a month). I use sandy soil, not pure sand. Set the planter in light shade for a few weeks or months. Then transfer the rooted cuttings to small pots.

I have planted what appeared to be dead tubers obtained from fellow cactus enthusiast in Nevada. After several weeks the tubers put forth new growth. This may occur in nature as a drought survival technique. In cultivation, here near Reno, NV, the plants respond well to modest watering throughout the summer. 

G. pulchella, 10-inch plant in central Nevada.

Same plant as above, closeup.

Garden-grown G. pulchella with tuber segments

Grusonia pulchella in flower, garden grown plant, Sparks, NV, click to enlarge image, photo copyright Charles W. Barnum.

External Links

Flora of North America, G. pulchella

G. pulchella, herbarium photo,  Missouri Botanical Garden W3 Tropicos Image