PLANT OF THE MONTH Library page 5
serves as a reference library of descriptions of cactus and succulent plants
designated as Plant-of-the-Month genera in the Cactus Chronicle newsletter.
This section will grow as the web master adds information on past and current POM selections.
Los Angeles Cactus and Succulent Society
Los Angeles Cactus and Succulent Society
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Sansevieria - September 2017, May 2015, April 2011, November 2009, April 2008 & 2007, September 2006
To many cactus and succulent growers, Sansevieria is something of an oddball group that gets thought of more as a houseplant than a real succulent. While it makes a great houseplant, it is an unfortunate way to look at this interesting genus of plants. I like to think of them as one of the very few groups of succulents that can tolerate, and even thrive in low light situations such as life inside a home. While most species can do well In-doors, that is by no means the required or preferred way to grow them. In our mild climate they can grow outdoors year round and make a great addition to the shadier spots of your landscape. They are among the easiest to grow and most tolerant of abuse of all succulents.
Sansevieria is a genus of approximately 70 species in the Asparagus family (Asparagaceae). Most species occur in Africa though some species have found their way to India and even Myanmar (Burma). The most notable differences between species are the length and shape of the leaves, as well as the coloration and patterning of the leaves. The common names "Snake Plant" and "Mother in law's Tongue" come from the long, stiff, pointed, and mottled leaf appearance of the most commonly grown species. However, some species produce much more interesting and unique leaf shapes. In particular, species such as S. cylindrica have leaves that are nearly circular in cross section.
In cultivation, many interesting hybrids and cultivars have been produced. Sansevieria hallii has several cultivars which carry variations on the the name "Baseball Bat". The name really is fitting as the leaves are very thick and tough. One of the most attractive species is S. kirkii. It has wavy leaves that are produced horizontally or at least low to the ground. The species has a brown to bronze cast which has been the basis for hybridization and cultivar selection. Cultivars such as "Coppertone", with its rich bronze and pinkish brown coloration, really show how beautiful the coloring of a Sansevieria can be.
Among the most popular types of Sansevieria are variegates. Most everyone has seen S. trifasciata 'Laurentii' even if you don't know it by name. It has long upright leaves with a yellow margin. It is not only one of the most popular Sansevieria, it is among the most popular of all houseplants. However, that is the tip of the iceberg. Variegates of S. pinguicula, S. robusta, S. kirkii and others can sell for $100 or more! For those looking beyond the typical yellow variegation, "Silver Streak" and "Siam Silver" are great plants with silvery-white variegation.
In recent years "minature" Sansevieria have become popular. They tend to have rounder leaves which only get a few inches long and look great in small pots. Unfortunately, most of these "minatures" are actually the juvenile forms of full sized species. Not only is the adult bigger, but it looks like a completely different plant. Sansevieria pinguicula and S. eilensis are examples of this. One of the only "minature" species I'm aware of that stays small and retains much of its juvenile look into adulthood is S. rorida.
Cultivation of most species is quite easy. They thrive in most any well drained potting mix. Outdoors they can grow in similar light conditions as Gasteria and Haworthia (i..e. bright shade, maybe some morning sun) or even shadier spots. They do well in ground, though they don't like being in an cold and wet for excessive periods. Propagation is simple. Either divide a large plant or grow new plants from leaf cuttings. Do note that leaf cuttings of variegated plants virtually always produce regular, non-variegated plants.
— Kyle Williams
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Sarcocaulon - February 2023, February 2015, January-February 2009, February 2008 & 2007
It is important to have a discussion about the proper name for these plants. Traditionally, Monsonia has referred to the plants in this group that are herbaceous while Sarcocaulon referred to the species with fat, woody stems (Sarcocaulon means "fat stem"). However, nearly 20 years ago botanists determined they were all members of the same genus, and the proper name for the genus is Monsonia not Sarcocaulon. More recent studies using the DNA of the plants confirms this finding is correct. While some may think it odd to have the herbaceous and woody species together, it really is no big deal. You only have to look to Pelargonium to see that a diverse array of species, from herbs, to woody shrubs, to geophytes, all happily coexist in one genus without anyone raising an eyebrow.
We focus on Monsonia, the Bushman's Candles, a genus of small succulents and caudiciforms native to South Africa. They belong to the Geraniaceae, or Geranium Family, and are closely related to the better known Pelargonium. Monsonia differs from Pelargonium primarily in having "actiniomorphic" flowers instead of zygomorphic ones. For non-botanists that means the flower of Monsonia are more or less circular and you could divide them into two equal halves no matter where you draw the line (like a pie or cake). Zygomorphic flowers are symmetrical in one plane only, just like a person's face. There is only one direction you could divide the flower in two with equal halves.
As for the plant themselves, they make wonderful additions to any caudiciform or winter growing succulent collection. The plants most commonly grown by cactus and succulent collectors are the woody Sarcocaulon group. They produce leaves when conditions are ideal for growth but drop them readily when the soil dries out, much in the same way as the unrelated Foquieria does. The flowers are usually white to pale pink, or even red, and an inch or two across. While called winter growers, it should be noted that some species, most notably Monsonia vanderietiae, are "opportunistic" growers that can grow most any time of year that it receives moisture. This is reflective of the Monsonia's habitat which is usually more arid than that of Pelargonium. However, that doesn't mean the plant will grow year round. During active growth water regularly, but provide little to no water when the plants decide to go dormant.
-Kyle Williams
Photos in Cactus Chronicle:
Sarcocaulon/Monsonia flowers, Sarcocaulon piniculinum,
Sarcocaulon vanderietiae
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Sclerocactus - March 2015
Sclerocactus has 15 species. "Sclero" means "hard" and it refers to the hard dry fruit (most cacti have soft fleshy fruit). All species are native to the United States, with most species occurring in the lower Great Basin Desert of Nevada, Utah, Colorado, northern Arizona and northern New Mexico. Plants are small and covered in dense spines. Interestingly, these plants do not flower as well for us as they do in cold climates. Freezing weather helps signal to the plants to develop flower buds. In our nearly frost free climate they don't get the signal as clearly. Even more challenging for us is growing the plants from seed. They require a repeated freeze and thaw cycle to germinate. That is easy to get in its native range, but for us it means we need to keep the seeds in the freezer and periodically take them out to let them warm up.
They will grow just fine in our climate and it is always nice to have some cacti from America in your collection. Especially ones from our most overlooked desert (from a cultivation standpoint), the Great Basin.
-Kyle Williams
Photo in Cactus Chronicle:
Sclerocactus parvilous
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Sedum - March 2015
Whether chosen intentionally or not, this month's Sedum, shares an unusual trait (for cacti and succulents) with our cacti of the month, cold hardiness. At least for many of the most commonly grown species which can take snow and prolonged periods of subfreezing weather. Unlike this month's cacti, Sedum is a gigantic genus of 400-500 species. Native Sedum species can be found from Europe to Asia, Mexico to Madagascar, and America to Africa. Even though Sedum reaches the tropics, it still shows its preference for cooler climates as they tend to occur at higher elevations on mountains in those regions. This pattern is not unusual for plants primarily known from temperate climates as many genera of plants, such as Rhododendron, Conifers, and Violets, have a similar distribution.
Sedum belongs to the family Crassulaceae which includes many of our most popular succulents like Crassula, Echeveria, Aeonium, Kalanchoe, and Dudleya. While it is difficult to generalize for hundreds of different species, Sedum tends to form stems like Kalanchoe instead of rosettes like in Echeveria. The stems can be tall and straight, though more commonly the plants grow as a subshrub or groundcover such as S. dasyphyllum. One of the most interesting and popular species is S. morganianum, the Donkey Tail, known for its long hanging stems densely covered with fat cylindrical leaves.
DNA research on the relationships between species and genera of the Crassulaceae has shown Sedum species appearing in and amongst many different genera of the family. This means that Sedum is what taxonomists euphemistically call a "garbage can genus". Put simply, when there is a species of Crassulaceae that does not clearly belong to one of the other genera it usually gets called a Sedum by default, especially if it is a stem forming species that isn't a Kalanchoe. That leads to unrelated species being put in the same genus, which isn't acceptable from a scientific standpoint. Expect to see Crassulaceae specialists rearrange things in the future. For you, the succulent enthusiast, what it means is that you should keep the same labels you have on your plants for now, but in the future you may need to change some of them if calling the plant by its correct name is important to you. One exception to that is that one of the most commonly grown species, Sedum spectabile, has clearly been shown to belong to a new genus Hylotelephium.
Flowers in Sedum can be particularly showy, especially in the species that form large clusters of flowers. Many species are grown for the flowers, with the plant being a secondary consideration. Hylotelephium (formerly Sedum) spectabile is an exceptionally popular species grown in colder climates. It forms big clusters of flowers at the end of long stems and is very tolerant of moist growing conditions, allowing it to be grown in regular flower beds back east where it gets rained on and irrigated regularly. The popularity of this species has led to numerous cultivars being created with flowers colors ranging from red to pink to white, and even purple and salmon orange.
Did you know that California has 15 native species of Sedum? That makes it our third largest genus of succulents (including cacti) in our state. Only Dudleya and Opuntia have more native species. Some are tiny annuals while others are larger perennials that are quite succulent. Some, like S. albomarginatum, look so similar to Dudleya that you couldn't tell the difference without looking closely.
-- Kyle Williams
Photos in Cactus Chronicle:
Sedum albomarginatum, Sedum morganianum, Sedum nussbaumerianum
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Sempervivum - March 2010
The genus Sempervivum is endemic to the mountainous regions of central and Southern Europe and the Mediterranean islands. The grow at anywhere from 3,000 to 8.000 feet and can therefore tolerate colder temperatures than other succulents. There are over 50 species and 3,000 cultivars. Sempervivum form smallish rosette clumps of many different sizes (1/2 inch to 3 inches), forms, textures, and colors. Like Aeoniums, Sempervivum produce a star-shaped flower stalk after which the rosette dies. Flower colors are typically red or pink. The rosette leaves may appear to be glossy or more matte. Hairy rosettes are found in the cultivars, where silver colored strands can occur along the leaf margins. Even more distinctive are the clumps of hair which can be found on the leaf tips. With some cultivars the effect is significant enough to produce a cobweb like appearance. Sempervivum are collected and prized for their forms and numerous colors.
-- Steve Frieze, February 2010
Photo in Cactus Chronicle:
Sempervivum collection
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Senecio and Othonna - January 2018, January 2012, January 2010
The two genera we are focusing on this month might not seem to have a lot in common, with one being a winter grower and the other a summer grower. The common thread is they are both members of the Daisy family, Asteraceae. The Asteraceae is the largest family of flowering plants with over 30,000 species. Only the Orchid family rivals it in size. As you’d expect in a family this large, species of Asteraceae can be found in every habitat all over the world. There are relatively few succulents for the size of the family, and the majority of these can be found in Senecio and Othonna.
Senecio is an enormous genus of over 1,250 species, making it the largest genus in the Asteraceae and among the top ten largest genera of all plants. While the genus is huge, only a fraction of them are true succulents. In fact, many Senecio are normal leafy herbs you’d see in a weedy field. However, it is the succulent ones that interest us. Among succulent Senecio there are two main “looks” or growth forms. The first are upright stem succulents with deciduous leaves (i.e. leaves that fall off after a short time). They often have bluish-green stems with interesting striped markings and generally (but not always) stay 1-2’ tall or less. You may see these plants listed under the old name “Kleinia” by some sellers, especially the species with bright red flowers. Some, like S. anteuphorbium get taller and make an interesting succulent shrub. The other type are trailing plants with thin stems and succulent leaves that make great hanging basket plants for shadier spots. These plants usually have small white flowers.
Othonna, with over 100 species, would be considered a large genus in most circumstances but seems tiny compared to Senecio! They are winter growing plants from the winter rainfall areas of Namibia and western South Africa. They are variable in form, with the most popular kinds having attractive caudiciform bases. Other types have fat elongated stems while others are geophytes which make annual stems that come up in the winter and die to the ground in the summer. Most make nice yellow daisy-like flowers. Cultivation of the woody species is very similar to Tylecodon or other woody winter growers, while the geophytic species can be treated similar to winter growing bulbs such as Albuca.
Photos in Cactus Chronicle -
Senecio rowleyanus, Senecio stapeliiformis
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Stapelia - September 2009
Stapelia and Caralluma are members of the Asclepiadaceae subfamily (formerly the family) of the Apocynaceae family (Bruyns, 2000). Both of these plants are described as stem succulents that belong to the Stepeliae tribe. They produce strong smelling flowers that are characterized as “carrion” with respect to their odor. The fragrance of the plants is linked to an intricate pollination mechanism that begins with the flies and other insects that are attracted to the flowers and that ultimately pollinate the flowers. The subfamily name is derived from the genus Asclepias (milkweeds). In addition to their unique floral fragrances, the flowers generated by these genera are also idiosyncratic with respect to their shapes, textures, and color combinations and are popularly called “starfish” flower plants.
Flowers are relatively short lived although in cultivation that have been known to sustain themselves for a few days. In good growing conditions, a sequential set of flowers are formed from the stems.
Propagation is relatively easily accomplished from cuttings or offsets that may be rooted in pumice. The use of a rooting compound such as Rootone (contains a fungicide) encourages successful propagation.
Stepelias and Carallumas should be grown in normal well drained cactus soil and watered thoroughly during the growing season. Mealy bugs can be an especially difficult problem with these two plants if an infestation takes hold. Preventive measures are a necessary and prudent step.
The natural habitat for Stapelias and Carallumas is Africa. Stapelias are typically found in the arid regions of tropical and southern parts of the continent. Over forty species can be located in Botswana, Zimbabwe, Namibia, and South Africa. They are also found in norther Zambia, southern Malawi, and central Mozambique
Steven Frieze, 2009
Photos in Cactus Chronicle:
Stapelia gigantea, Caralluma socatrana
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Stenocactus - July 2017, August 2013
Stenocactus and Echinofossulocactus are the same genus. The name of this easy to grow and uniquely ribbed genus has been a subject of contention since the 19th century. The genus was originally described in 1841 by George Lawrence, but the description was invalid. It was re-described in 1898 by Karl Schumann. Various attempts to straighten out the names went on for the next hundred years. With blessings from the Committee for Spermatophyta, (no one else knows what it means either), Kew Gardens, and the International Cactaceae Systematics Group, the name Stenocactus seems to have finally triumphed.
Echino traces to Echinus, which is Latin for Hedgehog, a spiny porcupine-like rodent from Europe, and also, equally likely, and much closer in appearance, a spiny, edible sea urchin from the Mediterranean. Stenos is Greek for narrow, an obvious referral to the many narrow ribs on almost all of the species.
They are all spiny plants, collected much more for the appearance of the spines and the wonderful curved ribs than their flowers, although the flowers can be quite showy. All of the species (there are ten) are very variable, and as a result, there are numerous varieties and forms that can enhance any collection. Most of the species are reasonably small, flowering at two years, when only an inch or so in diameter. A good representative collection can be kept on a table.
Stenocactus are native to Central to Northern Mexican. The genus is closely related to Ferocactus, differing by the lack of nectar glands, the lack of a ring of hairs above the stamens, and size.
Stenocactus grow in grass lands, and need some protection from full sun. They are easy to grow, putting on most of their body weight each year in the early spring to summer. Plants growing outdoors will grow slowly during the winter using just the water from winter rains. It is important not to fertilize during the darker days of December, January or February, or etoliation or stretching of the body will occur. The narrow ribs, the wooly areoles, and the dense spines are an ideal habitat for mealy bugs. Frequent inspection of the plants will prevent them from spreading. Older plants sometimes get corky near the base. Keeping the plant in continuous growth delays this, but in some species the cork is inevitable.
Identifying the species of an Stenocactus is as difficult as identifying the genus is easy. For the most part, they tend to look alike, and there are far more names than there are species. However, a few species do stand out.
-- Kyle Williams, with Special Thanks to Tom Glavich
Photos in Cactus Chronicle:
Stenocactus (Echinofossulocactus) phyllacantha, Stenocactus (Echinofossulocactus) tricuspidatus,
Stenocactus vaupelianus
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Strombocactus - August 2014
Strombocactus is monotypic. The sole species of the genus is S. disciformis. Its native habitat is on limestone cliffs in central Mexico. This harsh, very dry, natural habitat is strikingly similar to that of Aztekium (albeit around 300 miles apart), and botanists at one time thought they belonged together in the same genus. All stay small enough to make nice potted specimens.
-- Kyle Williams
Photo in Cactus Chronicle:
Strombocactus disciformis
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Synadenium - July 2007
research in progress
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Tephrocactus - July 2011
Tephrocactus, is a genus of very variable cacti, mostly from Argentina. Species vary considerably, from the very spiny Tephrocactus stramria to the paper spined Tephrocactus articulata to the nearly spineless Tephrocactus inermis. Tephrocactus are probably the most collected of the Opuntioideae, and there is even a Tephrocactus study group for the true fanatics. They make small, neat plants, and a good collection can be kept in a reasonable area.
Tephrocactus typically consist of short knobby joints that are either globular or cylindrical. Emanating from each of the joints are sharp spines or glochids. This genus is distinguished by its branching structure with shoots forming in vertical columns.
All cuttings root easily. Seed propagation requires patience, with seed scarification and sometimes artificial wintering Propagation of all Tephrocactus is most accomplished by cuttings or from the joints that comprise the plant by keeping the seed damp and cold in the refrigerator required. Seed germination can be erratic, with seeds from the same plant sometimes germinating in days, and sometimes not for months.
Handling of Tephrocactus is somewhat problematic. They are notorious for sharp spines, and nearly invisible glochids that are easily lodged in the unsuspecting hand of inattentive hobbyists. Handling plants with tongs or other tools for this purpose is the best way to avoid having spines lodged in your hands. Gloves are not necessarily the answer with this genus as they get covered with glochids, which invariably end up in your hands when the gloves come off. Glochids can often be removed by washing with a strong hose stream. Plucking with tweezers is effective and brushing works sometimes. Duct tape is a help, and as a last resort, so is rubber cement.
Photos in Cactus Chronicle:
Tephrocactus articulatus v. papyracanthus,
Tephrocactus Alexanderi, Tephrocactus molinensis
Tom Glavich March 2005
Edited by Steve Frieze, July 2011
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Thelocactus and - August 2018, September 2014, June 2010, March 2008 & 2007
Hamatocactus - August 2018
Thelocactus are spectacularly beautiful cacti with dense multicolor spination, well shaped tubercles, and large colorful flowers. They have been a favorite with collectors since they were first discovered. Thelocactus is a small genus in the cactus family, with only 11 or 12 species. In addition to the species, there are also half a dozen legitimate varieties, and a large number of less legitimate varieties that can be found in reference books and collections. The larger number of questionable varieties is due to variability of some of the species between populations from isolated locations.
Thelocactus are found from Southern Texas through central Mexico, mostly in the Chihuahuan Desert, but extending into brush land and thorn scrub in the western parts of its range, and into the Rio Grande Plains region in Texas. Thelocactus bicolor has the largest range, extending from central Chihuahua in the west into Texas in the north, and as far south as San Luis Potosi.
Thelocactus are easily grown, tolerant of heat and moisture, but not cold and moisture. They benefit from protection from being cold and wet, although plants left unprotected during the last several winters survived in good shape. Some species develop fairly large tap roots, and should be planted in deep enough pots to give them room to grow. They are easily propagated from seed, and this is the best way to develop a good collection from different populations. They can also be propagated from offsets, with a cutting allowed to dry, and then replanted.
The relationship between species of Thelocactus and other genera is somewhat uncertain. There is evidence to suggest the genus may need to be broken up, or at least have some species transferred into it. Originally, the genus was split out of Echinocactus, but isn't thought to be especially closely related to it today. Several other genera have been linked to Thelocactus, including Echinomastus, Leuchtenbergia, Glandulicactus, and Ferocactus. In addition the genus Hamatocactus has been bounced around between Thelocactus, Ferocactus, & Hamatocactus with some taxonomists dividing it up between the three, with some species being moved into each genus. More studies of DNA are needed before this can be sorted out. Until then keep calling them Thelocactus and enjoy the plants!
Photos in Cactus Chronicle:
Thelocactus bicolor, Thelocactus hexaedrophorus,
Thelocactus setispinus, Thelocactus macdowellii
-- Kyle Williams
Special thanks to Tom Glavich
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Trichocereus - May 2010
. . . easy to grow, and will reward the grower with spectacular flowers. Modern taxonomy has combined Echinopsis, Lobivia and Trichocereus and most recent authors have described all three under Echinopsis.
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Turbinicarpus - September 2016, June 2011, August 2009, September 2008 & 2007
Turbinicarpus is a small (but growing) genus of small plants from Northeastern and Central Mexico. It is one of several closely related genera, Neolloydia, and Gymnocactus, and Strombocactus being the ones most frequently mentioned. In many books, some of the plants listed below will appear as either Neolloydia or Gymnocactus. The exact relation of these genera is still being worked out and the disagreements between botanists are substantial. New species have been discovered and named in the past decade; seeds and plants of these are just becoming available.
All of the Turbinicarpus species are worth growing. They are all small, most full sized in collections at an inch or two. A few will clump readily, and make impressive show specimens, as shown below, but still remain manageable. A collection of all the species and varieties could easily fit on a table top.
In habitat, Turbinicarpus usually grow under the protection of larger plants, generally shrubs that offer some protection from the worst of the mid day sun. Turbinicarpus have large tuberous roots, which are their primary food and water storage source in times of drought. Over much of their habitat, rain falls during the summer, and growth is most rapid during this period. They can take lots of heat.
Turbinicarpus are fairly easy to grow, if attention is paid to their life cycle. They are dormant in winter, from November through mid-March. As they begin growth, watering has to start slowly. If too much water and fertilizer is given at once, it’s possible to burst the skin of the plant. Once growth is going (April and after) water freely. During very hot weather in the summer, the plants sometimes go dormant again for a short period. Attention has to be paid to watering again.
If a head splits, all is not lost. The entire head can be removed, and the top of the tuberous root left half an inch above the soil. It will usually start two or three new heads. Removing a head is also a great way for vegetative propagation. Turbinicarpus can be raised from seed. They are slow for the first year, but reasonable size plants can be grown in a year or two, and flowers the size of the plant will appear by the second year. Producing clumps as shown above will take quite a bit longer.
Photos in Cactus Chronicle:
Turbinicarpus schwarzii, Turbinicarpus subterraneous
Tom Glavich, February 2002
Edited by Steve Frieze, June 2011
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Tylecodon - January 2017, November 2012, November 2009, January 2008
Tylecodon is a member of the Crassulaceae Family. It is a winter-growing plant which looks at its best from late fall through early spring.
Tylecodon is a relatively new genus first published in 1978. In books published before this date, most plants that we know today as Tylecodon will appear as Cotyledon. The name Tylecodon is actually an anagram of the plant genera Cotyledon. In habitat (this typically occurs in cultivation as well), Tylecodon are generally deciduous, losing their leaves in summer.
Tylecodon consists of about 46 species among them the relatively ubiquitous species Tylecodon paniculatus. They are described as a small shrubby plant and originate from South Africa and Namibia.
The leaf structure is comprised of a coiled grouping of leaves (often vertical and needle-like) which emerge in late summer or early fall. Flowers appear at the end of the growing cycle in late winter or early spring. Tylecodons vary in shape and size with some species being as small as an inch while other can reach 6 feet in height.
Most Tylecodon are valued for their caudex-like stem structure and are relatively hardy in Southern California. Excessive watering during their dormant season can cause rot. Cutting can be rooted rather easily and are a good way to propagate this plant
Photos in Cactus Chronicle:
Tylecodon paniculatus in habitat, Tylecodon pearsonii
References
H. Jacobsen, A Handbook of Succulent Plants
M Sajeva and M. Costanzo, Succulents, The Illustrated Dictionary
Tom Glavich December 2002
Edited, Steve Frieze November 2009
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Raphionacme - August 2014
Raphionacme contains 37 species of mostly geophytic shrubs, with only a handful of climbing species. However, the most commonly cultivated species R. flanganii is a vine and therefore is the habit people associate with the genus. While most species are in southern Africa, the genus can be found from South Africa, through tropical Africa, and even into Arabia. It grows in a wide variety of habitats ranging from deserts to tropical rainforests. The plants we usually see in cultivation tend to be South African species that are adapted to a dry, non-tropical, climate like our own.
Cultivation for the most commonly grown, South African, species of these genera is fairly easy. Treat as a summer growing succulent that doesn't like to dry out completely. Most plants will go dormant or semi-dormant in the winter and shouldn't be watered as often, though they seem fairly tolerant of our wet winters if the soil is well drained. The tubers/caudex grow the fastest when buried, so it is advantageous to grow them that way for several years before raising them.
-- by Kyle Williams
Photo in Cactus Chronicle:
Raphionacme burkeri
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Rebutia & Sulcorebutia - August 2019, July 2016, May 2013, April 2009, March 2008 & 2007
Rebutia and Sulcorebutia are both genera from the highlands of Bolivia and Northern Argentina. They are similar in appearance, in habitat and culture. Coming from high altitudes, they are both tolerant of cold, and if dry, can be left out in all weather. The populations of Sulcorebutia and Rebutia overlap, but there are no natural hybrids are known.
Both genera are easily grown. They are dormant in winter, and start to grow in late March or April. They flower from April through June, with the peak flowering period varying from year to year depending on the weather. Two flowering cycles are common in cultivation in California. The flowers are almost always numerous, and vary in color from purple and red through orange to yellow. They do well in normal compost, and grow best with steady fertilization, when in active growth. They are both attractive to spider mites (Sulcorebutia more so, particularly the ones with few spines.) Damage can be prevented by frequent inspection, and a weekly, forceful wash down with water.
Propagation from offsets is easy. The offsets should be cut off, left to dry for a few days, and then replanted. Very small offsets can be successfully rooted. Seed is easy to germinate, but is short lived.
There has been debate from the start on whether or not Sulcorebutia and Rebutia are the same genus. (Current thinking is that they are.) The issue will ultimately be settled by genetic studies. For the present they are treated as separate genera, and they appear this way in almost all references, catalogs and show schedules. Both genera cover large altitude ranges, and many species are so variable that collections from nearby populations or even the same population at different times have been given different names. There are far more names than species. The books by John Pilbeam help make sense of the species and varieties.
March 2005 by Tom Glavich
Edited by Steven Frieze, 2009
Photo in Cactus Chronicle:
Sulcorebutia rauschii entered in the 2001 Intercity Show by D. & E. Tufenkian
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