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Henry Shaw
Cactus and
Succulent Society

A CSSA Chapter
St. Louis, Missouri


Along with other articles, columns and club updates, each monthly issue of the Henry Shaw Cactus Digest includes an article or two on members' favorite cactus and succulent species. The articles typically include photos and facts on the plants' natural origins and distribution, growing conditions, common and scientific names, care and cultivation tips, and helpful hints for encouraging flower production.
Follow the links below this month's offering(s) to enjoy previous Plants of the Month or click to read a sample of the HSCSS Digest in PDF format.


July 2018 -- Euphorbia coerulescens

By Chris Walker
My new plant of the month "win" is Euphorbia coerulescens, and what a gnarly, fierce beauty it is. Euphorbias are a large genus of plants of over 2,000 different species. They are commonly called spurges, which refers to the purgative nature of the latex substance that serves in the vascular system just under the surface of the plants.
A Greek physician named Euphorbos, who served King Juba of Numidia around 50 B.C. to 23 A.D., used the latex of a particular species of plant for its purgative nature and prescribed its use for the king. King Juba then named the plant after his physician. Much later in 1753, Carl Linnaeus assigned the name to the entire genus. The species name of the plant I won, coerulescens, refers to the bluish color of the stems.
Eurphorbia coerulescens occurs in the Noorsveld desert area of Cape Province, South Africa. It grows alongside other succulent species like Portulacaria afra and is foraged by elephants. E. coerulescens covers large tracts of land in this area, where farmers use it to feed their sheep when drought conditions persist. They cut the stems and let them dry for a while. Once the latex dries out, the caustic affect is greatly reduced.
The plant naturally grows into rather sculptural, upright columns with uneven growth. Generally, the species reaches about 2 to 6 feet tall. E. coerulescens is considered leafless, although some plants develop small, temporary leaflets at the apical tips. In fact, my plant has these leaves, which is an exciting sign of life this spring.
E. coerulescens develops four to six vertical ribs. Thick thorns that grow in pairs form on the edges of the ribs. Small, yellow flowers appear between the thorn pairs. As the flowers fall off, they leave behind scalring along the edges, contributing to the gnarly look of the plant.
Euphorbia flowers exhibit a complex form called a cyathium, in which tiny, minimally formed male flowers surround a single female flower. There are no flower petals, no sepals. The "cupcake" part holding the flowers together is called an involucre. Euphorbias are the only plants known to have this kind of flower head. E. coerulescens flowers in early to mid-spring to early summer.
This plant is rated Zone 9b (annual minmum temperature of 25 degrees F) and prefers a neutral pH of 6.6 to 7.5. It prefers full sun but can tolerate partial shade. E. coerulescens should be grown in a well-draining potting mix. Water well in the active growing season and keep it dry in winter.


July 2018 -- Fockea

By Bob Williams
A signature plant of the Henry Shaw Cactus and Succulent Society is "Bad Hair Day," Pam Schnebelen's Fockea edulis. It is pictured in our show and sale ad, and people come to our show in part to see this plant.
For the last of the four plant groups in my ongoing experiment examining the effect of pot size on caudex development, I selected Fockea in part because of Bad Hair Day. I know none of my plants will come anywhere close to its size in three years, but maybe I will get something interesting.
One thing I can say about my plants is that they are going to the dogs. Fockea is a member of the large Apocynaceae family. Per the Plant List, it includes 410 genera and over 5,500 species. Some of its more recognizable members are Adenium, Fockea, Hoya, Huernia, Pachypodium, Stapelia and Vinca. This group of flowering trees, shrubs, herbs, stem succulents, tuberous plants and vines is commonly known as the dogbane family. Dogbane is derived from Greek for "away from dog," since some plants were used as dog poison. Members of this family are found on every continent, from temperate regions to rain forests.
Fockea is a small genus inside Apocynaceae. There are only six species with 12 synonyms: F. angustifolia, F. capensis, F. comaru, F. edulis, F. multiflora and F. sinuata. Fockea is named after Dutch botanist Charles Focke. These plants are found in eastern and southern Africa. Even though all species within Fockea are known for their caudices, these plants are not found in the driest and hottest regions where they grow. They have swollen, sometimes warty tubers, which grow underground, and branching stems with opposing leaves. The stems readily bleed a milky latex when bruised.
Despite the latex, the tubers of several Fockea species are edible and were roasted and eaten by the Hottentots. Prolonged cooking is said to inactivate the latex. Once roasted, the tubers can be dried and ground into a flour to make bread. The edulis in Fockea edulis means edible. It is reported that raw tubers were also used as a source of water in periods of drought. People would pound the tubers and squeeze out the juice.
Fockea flowers are small and almost inconspicuous. White and yellow seem to be the most common colors. Those in our hobby grow these plants for the caudex, not the flowers. A fockea caudex can reach 30 inches in diameter or more. The vines of fockeas accent the caudex. The vines tend to be slightly thicker than those of most vining caudex plants. The leaves can be over 1 inch long and are "crinkled." The vines typically need a trellis for support. They can grow 10 feet or more in a season.
Careful pruning is advised. The leaves will fall off in the winter and come back again in the spring. The foliage attracts whiteflies, and periodic spraying with an insecticide or fumigation may be required to control this problem.
Fockeas are fairly easy to grow and tend to be hardy after getting past the seedling stage. A fast-draining soil mix is best. The caudex should be planted below ground level with the top at ground level. Keeping the caudex buried will result in faster growth. At show time, the plant can be raised to highlight the caudex. Subsequent replanting deeper does not affect growth. To help with growth, a high-nitrogen fertilizer should be used with a lower potassium level. Bright, indirect light is recommended.
The plants can tolerate high heat, but do not like full midday sun. This can discolor the caudex, if exposed. They can tolerate temperatures in the upper 30s for a short period of time.
As is normal, watering should be reduced in the winter, but not eliminated. Also, watch out for mice, as the literature says the pests like the taste of the caudex. Propagation is by seed. The plants are dioecious, so a male and a female plant are needed for pollination. I am not sure how you determine which is which.
The plants I am growing are Fockea crispa, which is a synonym for Fockea capensis. This plant was described in 1839 by a botanist named Endlicher and is found in the cape region of South Africa. What differentiates this plant from the others is that the caudex is rougher or "wartier."
My plants are doing well and showing good growth. I don't have 10-foot vines yet, but that day may come. These plants are readily available from most suppliers, and starter plants are reasonably priced. Plants like Bad Hair Day may cost more.
The Plant List -- http://www.theplantlist.org/browse/A/Apocynaceae/Fockea/
Giromagi Cactus and Succulents -- http://www.giromagicactusandsucculents.com/fockea-giromagi-cactus-succulents/
Khumbula Indiginous Garden -- http://kumbulanursery.co.za/plants/fockea-edulis
The Succulent Plant Page -- http://www.succulent-plant.com/families/apocynaceae/asclepiadaceae/fockea.html


July 2018 -- Puna, a Cactus With Many Names

By Nikki Murdick
Historically, it is said that the genus Puna was created by Roberto Kiesling in 1982 to encompass just two plants, which earlier had been known as Opuntia subterranea, named in 1905, and O. clavarioides (1837). The reason for his combining these plants into their own genus was to group plants with similar morphological characteristics -- growth habits and taproots.
Then, in 1997, a new plant was discovered, described and included with the previous two. This plant was known as Puna bonnieae. Since that time, more detailed studies of seed structure and DNA indicated these plants are more appropriately placed in the family Opuntioideae.
These three plants have had numerous names and been considered in the Opuntia, Tephrocactus, Cumulopuntia and Maihueniopsis genera, as well as Puna, so you may find these plants labeled with any of those names. In addition, the three Puna plants now have been expanded to include three additional subspecies: P. bonnieae cv. Inermis, P. clavarioides f. cristata and P. subterranea f. incahausi.
All of these plants come from high-altitude areas, usually growing at about 3,000 meters above sea level in Argentina or Bolivia. They typically grow hidden in grass or shrubs, or among rocks. During the winter, their long taproots pull them down into the soil. If you grow these plants, they need a deep pot with well-draining soil. As with other high-altitude cacti, they need a lot of light, as well as a cool, dry winter rest period.
If you like small cacti that are slow-growing, have beautiful flowers and don't take up much room in your collection, these are the plants for you. After you consider each of the six forms described below, you will probably want to collect them all.


Puna bonnieae
Puna bonnieae or Maihuinopsis bonnieae, now based on recent research to be called Tephrocactus bonnieae, is endemic to Argentina and found in a very restricted range at about 3,000 meters altitude. This small geophytic plant is difficult to find during the dry season, when it shrinks into the soil for most of the year. It is considered endangered because of its very restricted range, which has been devastated by collectors.
Puna bonnieae f. inermis
Puna bonnieae f. inermis or Maihueniopsis bonnieae cv. Inermis comes from a small area in the province of Catamarca in Argentina at about 3,000 meters above sea level. In cultivation, it is often spineless, while in the wild, it typically has very short, flat spines; the spineless version is very rare. Both types of Puna bonnieae have a fat taproot, so growing them in cultivation requires deep pots and a well-draining potting mix. They tolerate light frost, but need to rest in a cool place during the winter period. Without this rest period, they do not bloom as well.
Puna clavarioides
Puna clavarioides or Maihuenopsis clavaroides comes from Argentina at an altitude of approximately 3,000 meters. Listed as the type species for the genus Puna, it is a low-growing geophytic cactus with subterranean stems arising from large roots. It grows hidden among rocks, where it mimics them, or is scattered under shrubs and in grasses, so it is difficult to find. It also can be found in extremely barren areas where other vegetation does not survive. Although it is abundant where it is found, it is considered threatened because of mining and tourism in those areas.


Puna clavarioides f. cristata
Puna clavarioides f. cristata or Maihuenopsis clavarioides f. cristata is a version with distinctive mushroomlike, conical stems. It also can have cristate, fan-shaped forms or branching fingerlike stems. A single plant can have all three forms, although in the wild, only the tops of the stems can be seen.
This plant is sometimes called Crested Dead Man's Fingers or the Crested Mushroom Opuntia. It is also a mountain cactus from Argentina, and like the other forms of this cactus, has a fat, elongated taproot. All the punas tolerate light frost, but require a cool winter rest in order to flower and even survive in cultivation.
Puna subterranea
Puna subterranea or Maihuenopsis subterranea is also found in Argentina as well as Bolivia. It is a single-headed plant with a deep taproot, as its name indicates. In cultivation, it may clump, although it is very slow-growing.
Puna subterranea f. incahuasi
Puna subterranea f. incahuasi or Maihuenopsis subterranea subs. pulcherrima is a subspecies that was discovered in 2000 near Incahuasi in Bolivia. It was originally described as Tephrocactus pulcherrimus, then as Cumulopuntia subterranean subsp. pulcherrima. Currently, there are questions as to whether it is a viable subspecies. This plant is also a slow grower, but does tend to proliferate more than the type species in both habitat and culture.
Selected Sources
The Cactus Family -- Edward Anderson, 2001
The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass -- Editors: James Cullen, Sabina G. Knees, H. Suzanne Cubey, 2011
The New Cactus Lexicon -- David Hunt, 2006
Encyclopedia of Cacti -- http://www.llifle.com/Encyclopedia/CACTI/Family/Cactaceae/15895/Puna_subterranea_f._incahuasi
CactiGuide.com -- http://www.cactiguide.com/cactus/?uname2=Puna subterranea
IUCN Red List of Threatened Species -- http://www.iucnredlist.org/details/40822/0

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