Family CACTACEAE & Subfamily OPUNTIOIDEAE
by Chuck Staples
from Mid-Iowa C&SS
A brief history of the genus Mammillaria and Mammillaria mammillaris
(Linnaeus) Karsten
by Chuck Staples
Mid-Iowa C&SS
EUPHORBIA CAPUT-MEDUSAE
By Chuck Staples
Mid-Iowa C&SS
FUNGUS GNATS
by Thomas Schwink
Mid-Iowa C&SS
SCHLUMBERGERA QUESTIONS
by Dick Kohlschrieber
The Epi-Gram South Bay Epiphyllum Society
Caudiciforms Explained - Pelargoniums
By Brad Johnson (with graphics)
Points of Interest; Colorado C&SS
Escobaria Minima
by Fred Gaumer
On the Dry Side Monterey Bay Area C&SS
EUPHORBIA: A HARDY PLANT GROUP FROM AFRICA
By Maureen Gilmer
On the Dry Side Monterey Bay Area C&SS
*************************************************************
Family CACTACEAE & Subfamily OPUNTIOIDEAE
by Chuck Staples
Mid-Iowa C&SS
The family Cactaceae are New World plants; originating in the North, Central & South American continents, including West Indies Islands (in the Caribbean), Galapagos Islands and other nearby islands. The latest classification of this family of plants recognizes four subfamilies - Pereskioideae, Maihuenioideae, Opuntioideae and Cactoideae.
One of the main distinctive difference from other plant families is the appearance of areoles in only the Cactaceae family of plants. Areoles are the places on a plant body where spines, flowers and branches usually occur.
All family Cactaceae plants produce a visible flower, all species are perennial and all are dicotyledons (which means that the plant on seed germination sends up two or more embryonic leaves - called cotyledons).
This article is primarily interested in the subfamily Opuntioideae:
Subfamily Opuntioideae
Plants are treelike, shrublike or clustering mounds. The primary distinctive difference from other family Cactaceae plants is the appearance of glochids in only the subfamily Opuntioideae at the areoles. Glochids are very thin, easily detached, minutely barbed, small spines, usually occurring in tufts at the areoles.
Distribution of the subfamily Opuntioideae plants range from as far north as British Columbia in Canada (continuing throughout USA, Mexico and Central and South America) to the southern tip of South America.
Take note of the 15 genera of the subfamily Opuntioideae below according to the latest book ``The Cactus Family'' (2001) by the late Edward F. Anderson:
Austrocylindropuntia Opuntia
Brasiliopuntia Pereskiopsis
Consolea Pterocactus
Cumulopuntia Quiabentia
Cylindropuntia Tacinga
Grusonia Tephrocactus
Maihueniopsis Tunilla
Miqueliopuntia
***********************************************************
A Brief History Of The Genus Mammillaria and Mammillaria mammillaris
(Linnaeus) Karsten
by Chuck Staples
Mid-Iowa C&SS
The genus Mammillaria is a part of the family Cactaceae and was first described by Adrian Hardy Haworth (1768-1833) in 1812. He was an English gardener, amateur botanist and entomologist, who studied natural history all his life. He was the leading English authority of his time on succulent type plants. He became a Fellow of the Linnean Society in 1798.
The name Mammillaria is derived from the Latin mamilla (meaning nipple or teat) which refers to the tubercles of the plant. These tubercles are very pronounced in the species Mammillaria longimamma A.P. de Candolle 1828.
Spelling of the genus was a problem in the early 1800s. Author Ludwig Reichenbach (1793-1879) used the spelling `Mamillaria' in 1827, while authors John Torrey (1796-1873) and Asa Gray (1810-1888) came up with the spelling `Mammilaria' in 1840. Various authors have used these two spellings over the years; however, the accepted spelling for this genus is Mammillaria (with two ms and two ls).
Unknown to A.H. Haworth in 1812, a John Stackhouse (1742-1819) used the name Mammillaria for a genus of algae in 1809. According to strict taxonomic rules the algae genus takes precedence for the Mammillaria name. It's interesting to note that cactologists Nathaniel Lord Britton (1859-1934) and Joseph Nelson Rose (1862-1928) were familiar with the algae problem with the name Mammillaria, and by following the strict rules of priority came up with a new name, Neomammillaria, to take its place in 1923 for the cactus plant genus.
However, since Stackhouse's algae name never came into actual use, the International Botanical Congress of 1930 decided to conserve Haworth's Mammillaria name under the family Cactaceae. (What a sigh of relief that must have been at the time for people that didn`t like the change to Neomammillaria.)
In his book ``The Cactus Family'' (2001), Edward Frederick Anderson (1932-2001) gives the following as synonyms of the genus Mammillaria:
Cactus Linnaeus 1753
Bartschella Britton & Rose 1923
Dolichothele Britton & Rose 1923
Mamillopsis Britton & Rose 1923
Neomammillaria Britton & Rose 1923
Phellosperma Britton & Rose 1923
Solisia Britton & Rose 1923
Chilita Orcutt 1926
Porfiria Boedeker 1926
Krainzia Backeberg 1938
Ebnerella Buxbaum 1951
Oehmea Buxbaum 1951
Leptocladodia Buxbaum 1951
Pseudomammillaria Buxbaum 1951
It's apparent that Britton & Rose split out a number of Mammillarias due to the shape of the plant or the color of the flower; as did Buxbaum. You may recognize some of the names. Two other genera, Cochemiea and Mammilloydia, having been associated with the genus Mammillaria in the past, have been recognized as separate distinct genera.
----------------
Mammillaria mammillaris
This plant has an interesting history. It evidently was the first known species of the genus and the only one known to Carolus Linnaeus (1707-1777) according to Britton & Rose. It was earlier described and illustrated in a 1697 book by Johannes Commelijn (1620-1692), published after his death by his nephew, Caspar Commelijn (1667-1731). The illustrated plate was from a colored drawing by Maria Moninckx (1673-1757) and has been used by numerous books over the last 300 years.
David Hunt (1938- ) tells us in his 1987 book ``A New Review of Mammillaria Names'' that this species was well known in Europe by the end of the 17th century. And, that it was illustrated in the book ``Phytographia'' (1691) by Leonard Plukenet (1641-1706) under the pre-Linnaeus Latin name `Ficoides s(ive) Melocactos mammillaris glabra, sulcis carens, fructum suum undique fundens'. He further says that the illustration may have been drawn from a plant in the famous garden of Henry Compton at Fulham, England. Since Compton exchanged a lot of material with the European Dutch gardens of the time, it is thought that this cactus plant came from the Dutch island of Curacao in the Netherlands Antilles of the West Indies in the Caribbean Sea off the coast of Venezuela, South America.
Linnaeus, when setting up his binomial nomenclature system of naming plants in his 1753 book, Species Plantarum, gave this plant the species name Cactus mammillaris. His description of the plant was `Cactus subrotundus tectus tuberculis ovatis barbatis' meaning `...the nearly round cactus covered with ovate, bearded tubercles...`. That description would fit a number of Mammillaria species today; however, in 1753 Linnaeus' description would be appropriate since it was the only cactus he knew of at the time with that shape.
When a taxonomist decides to set up a new generic name, this person also adds a specific epithet which together is referred to as the `type' of the genus. Haworth did this by making M. simplex as the `type' of the genus. As late as 1983 the International Botanical Congress decided that M. simplex was an illegitimate name for Linnaeus' C. mammillaris and conserved C. mammillaris as the type of the genus. What this means is that the earliest specific epithet (in this case `mammillaris') for that particular plant species must be retained even when a taxonomist splits out a group of plants into another genus. For historical purposes M. simplex becomes an illegitimate name and is generally listed as a synonym of M. mammillaris.
[For those of you not familiar with the use of initials in the above and following paragraphs, `M.' stands for Mammillaria and `C.' stands for Cactus. This is used to shorten the genus name after it has been established in the article, and each initial refers to the immediately preceding genus name used in the article. The genera Mammillaria and Cactus were used in previous paragraphs.]
Credit for describing M. mammillaris goes to Gustav Karl Wilhelm Hermann Karsten (1817-1908) who described the species name in 1882.
Distribution of this plant is from Curacao and neighboring islands of the Netherlands Antilles, the Lesser Antilles, Trinidad, Tobago, and Venezuela. It is generally found on limestone hills and/or outcrops in these tropical American sites.
Since Haworth's `M. simplex' didn't survive the name game, does any other Mammillaria species of his survive? I don't know how many Mammillaria species he named in 1812, but I found two still with us from 1812 (according to Anderson`s book ``The Cactus Family``): M. discolor and M. prolifera. There are also two that he named in 1824 that are still with us: M. geminispina and M. magnimamma.
Mammillarias are wonderful pincushion type cacti. You don't see Mammillaria mammillaris in retail stores much due to its difficulty to grow away from the tropics.
I hope you enjoyed this little bit of confusing cactus history.
Book References:
Britton, NL & Rose, JN (1923): The Cactaceae, Vol 4.
Craig, RT (1945): The Mammillaria Handbook.
Pilbeam, JW (1981): Mammillaria, A Collector's Guide. (1999): Mammillaria.
Hunt, DR (1987): A New Review of Mammillaria Names.
Anderson, EF (2001): The Cactus Family.
*******************************************************************
EUPHORBIA CAPUT-MEDUSAE
By Chuck Staples
Mid-Iowa C&SS
This species was first described by the "father of modern botany", Carolus Linnaeus (1707-1777), in 1753. The specific epithet, caput-medusae, means the 'head of Medusa'.
In Greek mythology, Medusa was the youngest of three monstrous Gorgon daughters of the sea god Phorcys and his wife, Ceto. These daughters were terrifying, dragonlike creatures, covered with golden scales and had withering serpents that supplanted their hair. They had huge wings and round, ugly faces; their tongues were always hanging out, and they had large, fang-like teeth. They were shunned because their glance turned people to stone. Their blood was poisonous. The hero in this myth was Perseus, who with the help of deities Hermes and Athena, killed Medusa and cut off her head for all to see. From her blood sprang the winged horse Pegasus, her son by the god Poseidon. (And the myth goes on......) ?
A mature Euphorbia caput-medusae is a perfect species to resemble the Medusa head and serpent-like appendages coming out of the head.
This plant species has a rounded main stem-apex with a long tapering taproot. The tuberculate side-branches resemble the serpent-like appendages of Medusa. In its natural habitat it grows near Cape Town, South Africa.
There are a number of other Euphorbia species of like character to the Medusa head. Some of these are: E. colliculina, E davyi, E. esculenta, E flanaganii, E fortuita, E. fusca, E. gorgonis, and E. inermis. They are all mostly dwarf species and all do resemble her head of snakes. All of the Medusa Head species come from Africa.
Another common euphorbia characteristic is the poisonous, milky sap - like the blood from Medusa that was poisonous. Depending on the species and individual person, the milky sap can cause painful irritation in open wounds of the skin, or in the eye.
It was interesting to note in the 4th Illustrated Handbook of Succulent Plants (2002), edited by Urs Eggli, that Philip Miller (169l-1771) described this species as Euphorbia fructus-pini in 1768 and, even more interesting, that Adrian Hardy Haworth (1768-1833) transferred this species to Medusea tessellata in 1812. He even introduced the genus Medusea in 1812; evidently to separate this peculiar looking plant from the genus Euphorbia. In any case, Linnaeus' Euphorbia caput-medusae still holds up as the proper name of this species; Miller and Haworth names drop into synonymy.
******************************************************************
FUNGUS GNATS
by Thomas Schwink
Mid-Iowa C&SS
The insects which are known in this country as fungus gnats and in Europe as Sciara flies are common and can be very destructive to succulents, especially seedlings. They are small insects and many people are not very aware of their presence, sometimes mistaking them for other small insects such as fruit flies.
As their name indicates, the food of these insects includes fungi and they can be very destructive to mushrooms. They feed on vegetable matter of many kinds, including plant roots. When they feed on small succulent seedlings, especially on the roots of these seedlings, they can seriously damage the seedlings and frequently kill them. Most of the damage is done by the larvae.
Identifying these very small insects requires magnification. I use an inexpensive 6X hand-held magnifier purchased from Toys R Us. Since these insects are also very active, most of us need an insect which is not moving (a dead insect) to make the identification. The most useful character for identifying adult fungus gnats is their long legs, especially their long coxae. The coxae are the proximal segments of the legs, the segments closest to the thorax. I make the identification using insects adhering to the sticky traps which I use. These traps are for sale by many gardening supply businesses.
CONTROL: I want to describe some of the control methods which I have used or at least tried, read about, or think would be worth trying.
Regardless of whatever else is done, heating the seed-starting mix prior to using it is highly recommended. This kills eggs of fungus gnats and is also effective against other pests, both insects and diseases, which may be present in the mix. Keeping the germinating seeds and the seedlings covered for as long as practical is also very effective. I like using humidity domes for this purpose, while many people use plastic bags. The increased humidity present when this is done usually facilitates germination and this is also very important of the seedlings.
Incorporating insecticide into the seed-starting mix prior to sowing the seeds -- This is something that I tried only once, with disastrous results. The insects were controlled, but so were the seedlings. Seedlings are often more sensitive to strong insecticides than are older plants.
Sticky traps -- I use these routinely and they do trap many insects, but many of the insects are not trapped and these insects do much damage. These traps are easy to use and their help in killing some of the insects is desirable. I look upon them chiefly as a monitoring tool which I can examine regularly and use to determine the numbers and kinds of insects trapped.
Dryness - Keeping the soil in the pots as dry as practical does help, but most seedlings are not tolerant of dryness of a degree that will deter these gnats. A thick gravel mulch also helps, but this too is not very practical with seedlings. A completely inorganic potting mix should also be of help, but I do not like using such a mix for seedlings.
Diatomaceous earth - Since the larvae of fungus gnats live in the soil and are very active, this product may be effective if mixed into the seed-starting mix or sprinkled on top. I have never read about this product being used against fungus gnats, but think that it may be worth trying.
Bacterial control - There are bacteria for sale which have been selected for their ability to control fungus gnats. However, although these may be effective when first used, with continued use the insects can develop resistance to the bacteria.
Predatory nematodes - These are widely sold for control of different insects, including fungus gnats. As with many insect control methods, including biological controls, enough gnats can survive to do considerable damage. I do think that these nematodes are worth trying, since they do not apparently harm the plants.
Mothballs - These have been recommended as a repellent for many insects and may be worth trying as a method to keep the adult gnats from laying their eggs in the seedling mix.
What I like best - I keep a spray bottle of a pyrethrin preparation handy when I examine my seedlings and when I take care of them. When I see a flying insect near the seedling pots, especially an insect that has flown from one of the seedling pots, I spray the insect. Even though what I use is an emulsion and may damage the seedlings if they are sprayed directly with it, the occasional droplet that may land on the plants when I direct the spray at the insects seems to do no harm. To be certain that the insect is dead after the spray has knocked it down, I squash it with my finger if I can find it. All insecticides should be considered potentially toxic, and thus I wash my hands after squashing the insect with my finger. Now that I have used this method for a period of time, I seldom see a fungus gnat and seldom catch one on the sticky trap in the room where I start my seedlings. Also, there is now very little if any fungus gnat damage to the seedlings.
**************************************************************
SCHLUMBERGERA QUESTIONS
by Dick Kohlschrieber
The Epi-Gram South Bay Epiphyllum Society
I had several people ask me how the commercial growers regulate when Schlumbergera are going to bloom. One of our members said she had been told by a nurseryman that you had to put your plant in a closet if you wanted it to bloom. That advice always makes me mad because it almost sounds cruel to do that to a plant. And it doesn't make that much difference in whether or not a plant will bloom. I have done this and came to the conclusion that most of these plants will bloom when they're going to bloom.
I also had been told to withhold water from the plant for a month and that would stress the plant enough to make it bloom. This is not true and has been proven to be harmful to the plant.
It happens that Schlumbergera are ``thermo-photoperiodic''. This means that their bloom initiation is triggered by a combination of day length and temperature. The primary trigger is the day length. Once the day length decreases to approximately twelve hours, the plant recognizes that it is time to bloom. Night temperature of 55 to 65 degree F. should accompany the short day.
Schlumbergera are very sensitive to light and plants that sit in the house and are exposed to any kind of light in the house, may not form buds. I have even heard of plants that are affected by a street light outside. I suppose that this is where the idea of putting your plant in a closet came from.
I have mentioned before how sensitive Schlumbergera are to temperatures. If nighttime temperatures go below 50-55 degrees, pinking occurs in the white, yellow and pastel flowers. That's why the warm temperatures we had the third week of November have affected the colors of my flowers and I've had less pinking than I've had in years. I have also found that plants that have flowers that have a lot of pink will lose most of the pink coloration if the plant is put in a warm area.
Growth regulators and other chemicals have been used to assist bud formation and bud drop and I'm sure that many of the commercial growers use them. It has been shown that spraying with benzylaminoprine (BA) increased the number of buds per segment. Silver thiosulphate has been shown to be effective in reducing bud drop.
FERTILIZING SCHLUMBERGERA - Most of the people that I know that grow a lot of Schlumbergera do not do a lot of fertilizing. I never have fertilized my plants as much as I did my epies and they seem to grow well and bloom a lot.
But when I have used a water-soluble fertilizer, the plants seemed to respond in a short period of time. Cobia, in his book Zygocactus (Schlumbergera) - A Comprehensive and Practical Guide For the Weekend Gardener, recommends using a 20-20-20 fertilizer 2-4 times a year. He also recommends leaching the plants with plain water to regular intervals to prevent the buildup of soluble salts. Fertilizer applications should stop at least one month prior to bud set.
McMillan and Horobin, in their book Christmas Cacti - The Genus Schlumbergera and its Hybrids, also recommend using a diluted well-balanced fertilizer and they also recommend leaching the plants with plain water.
They also say that fresh mulches of organic matter such as peat or leafmold, or even old tea leaves, placed around the plant on the soil surface can be beneficial and can keep a plant going for several years without repotting. They repeat a story that they published in an early issue of EPIPHYTES that I always liked. It was about a Christmas cactus, owned by an elderly woman, 4 feet in diameter in a 7-inch pot, in fine condition and full of bloom. It had been repotted 32 years previously and over the years was watered with tea and mulched with tea leaves.
REPOTTING - I have learned the hard way that you shouldn't be in a hurry to repot your Schlumbergera plants. The plants seem to do best when they are tightly potted. If you have a plant in a four-inch pot and want to repot it, I'd put it in a five-inch pot. It's also a good idea to use a pot that isn't too deep.
PRUNING - I have always pruned my plants right after they quit blooming. The experts recommend waiting until Spring and it may be that if you want to start new plants from your cuttings that result from pruning, they might root quicker in the Spring. Some of the experts recommend taking off at least 2 segments from each branch. I usually take off enough segments to even out the plant all around. On many of the Cobia hybrids it's essential to do some pruning or you'll just have these long unattractive stems. By the way, it's better to twist off the segments rather than cut them.
After the plants quit blooming, they very often look terrible. Some of my plants that bloomed early, look wilted. Wilting in Schlumbegera does not mean that the plant needs water but more often it means that the roots have rotted or that it's stressed in some way. Always pull on the wilted plants and if the roots have rotted, the plant may pull out of the pot easily. If the roots haven't rotted, put the plant in a shady area and cut back on the water.
I have quoted a lot from McMillan and Horobin's book and also Mark Cobia's book. CHRISTMAS CACTI - THE GENUS SCHLUMBERGERA AND ITS HYBRIDS by A.J.S. McMillan and J.F. Horobin is still available through Rainbow Gardens Bookstore. It is a wonderful reference book filled with color pictures and a list of all of the hybrids, including the Australian ones that were known at the time of publication.
***********************************************************************
Caudiciforms Explained - Pelargoniums
By Brad Johnson
Points of Interest; Colorado C&SS
Description
I feel it is important to first dispel any confusion about Pelargoniums and Geraniums. What many may not know is that a geranium is actually part of the genus Pelargonium and not the genus Geranium. The confusion can be traced back to the 18th century where Linneus, the father of modern botanical nomenclature (description and naming of all plants), first separated the two genera. However, the lack of communication between botanists and horticulturalists coupled with the reluctantcy for people to accept new ideas and change their views reinforced the confusion in the two names. Over time most botanists became used to the genera separation however, the confusion in names was already firmly established and most did not recognize the importance of keeping their plants accurately named.
Pelargoniums can range from shrub-like or stem succulent, pachycaul, or underground geophytes. The attractive flowers and relative ease of culture make this genus popular with many growers and is attributed to their gaining popularity especially the caudiciform or better term, geophytic Pelargoniums. Of the more than 230 species of Pelargonium approximately 185 are concentrated in the in the winter rainfall area of the south to southwestern portion of the African continent. The southeastern part of southern Africa (summer rainfall) has about 15 species. Another 18 species are found in the rest of Africa, while the remaining 12 or so are locating in other parts of the world.
While it is true that Pelargoniums are gaining in popularity, only a handful of specialty online nurseries offer them in any great variety. If you are able to find them for sale, most will be extremely small in size and moderately priced.
Characteristics
I would characterize most Pelargoniums to be fairly hardy and hassle free. From my experience, they tend be more tolerant then some of the other miniature geophytic succulents. The most significant distinguishing characteristic of Pelargoniums is the ``orchid like'' flowers they bare in throughout the winter growing season. I have seen Pelargoniums flowers in all sorts of vivid colors, patterns, and shapes. I should note however, most of these flowers tend to be small just like the plant. I highly recommended Pelargoniums not only for the ease and small size but also a wonderful plant to brighten anyone's greenhouse in the winter months.
The caudex on the geophytic species will form all sorts of unusual shapes and in some species, will grow to a fairly decent size over a long period of time. The caudex can be raised for effect and reduce the risk of rot. I have not observed any of the geophytic species to grow fairly rapidly and in fact, most will grow so slowly that they can be kept in the same pot for years. I hate to spotlight only the geophytic species in this genus, and would also highly recommend some of the stem succulent species. Many of these species will form excellent bonsai specimens in time. I have noted these species below as recommended stem succulent species.
It is also worth noting this species' highly variable leaves. They can range from all sorts of shapes and designs in just about every shade of green. Some can be fuzzy and lily pad like while others resemble ferns. Truly another amazing characteristic of these wonderful species that offering something for everyone.
Growing Conditions
Just like Othonnas, most Pelargoniums tend to thrive in cooler temperatures than most other succulents and have very similar growing requirements. As noted, most are winter growers however you can find a handful that are summer growers. Throughout their growing period, Pelargoniums will thrive with ample watering and reward you with extensive leaf and flower formation. When temperatures warm up in the spring and summer, reduce watering and allow the plants a resting period where most if not all leaves will drop. A strict resting period is critical for some species to promote ample flower formation in the coming growing season.
All of my species favor partial sun exposure in a south facing direction with a maximum of 3-5 hours of direct light. This limited amount of direct sunlight, in my experience, fosters the greatest amount of leaf and flower formation in combination with abundant watering and cool temperatures. This genus is suitable and recommended for those without a greenhouse and have access to a windowsill meeting the above requirements.
A common cacti / succulent soil mix should be ok and additional drainage material would be recommended for the larger more established species only. I have found that a soil mixture too porous will cause the smaller plants to dry out and die. The geophytic Pelargoniums are not conducive to Colorado's cold winters and therefore will not survive outdoors if the temperature reaches less than 40 degrees.
Propagation
Very few people have any troubles propagating Pelargoniums from seed or cutting. As noted earlier, most species flower freely throughout the growing season and have both male and female parts that are easily pollinated by hand. Seeds will form fairly quickly after pollination and are easily harvested. Pelargonium seeds are fairly unique in their design. They are similar to Othonna seeds in that they have small hairs on the end that act as a parachute which are easily distributed in the wind. Further, the seed and the parachute is connected by a spring or corkscrew type structures that acts to screw the seed into loose soil. Pelargonium seeds are some of the easier seeds to propagate with a greater success rate if sown shortly after harvesting. I have had greater success if the seeds of winter growing species are sown immediately after harvesting and when the temperature is still fairly cool (70 degrees max) with nightly fluctuations.
Propagation from cuttings is also possible from the stem succulents and rhizome forming species. Both, from my experience, will form typical plants and in some cases the rooted cuttings will flower more freely. Cuttings should be taken soon after the growing season starts when new growth is present. While cuttings do not ensure genetic diversity, it is the easier but not the only method for propagation.
Recommended Species (geophytes)
Pelargonium antidysentericum, P. auritum, P. barklyi, P. campestre, P. caroli-henrici, P. crassicaule, P. hirtipetalum, P. incrassatum, P. leptum, P. lobatum, P. luridum, P. nephrophyllum, P. oblongatum, P. oxaloides, P. radiatum, P. sidoides, P. triste
Recommended Species (stem succulents)
Pelargonium carnosum, P. cortusifolium, P. cotyledonis, P. ferulaceum, P. klinghardtense, P. mirabile, P. succulentum
Next month I will discuss caudiciform Fockeas. Fockeas are a wonderful group of plants that form a very showy caudex and are extremely easy plants to grow under just about any conditions.
References:
http://www.pelargoniumsandgeraniums.net/
Pelargoniums of Southern Africa Vol. 3 Van Der Walt and Vorster, 1988.
Rowley, Gordon D. Caudiciform & Pachycaul Succulents. Strawberry Press, 1987.
If you would like to contact me, you can email me at brad_w_johnson (at) hotmail.com or visit my website at: http://communities.msn.com/TheCaudiciformPachycaulSucculentSite/_whatsnew.msn.
************************************************************
Escobaria Minima
by Fred Gaumer
On the Dry Side Monterey Bay Area C&SS
One of the few things from Texas that never gets too big. Sometimes seen labeled as Coryphantha Nellii or Coryphantha Minima or Escobaria Nellii. Escobaria Minima seems to be the currently accepted name for this little plant. About a year ago a member brought in an article from a gardening magazine about the petite Texan, saying that in its natural habitat it is very rare, possibly on the edge of extinction. Texan ranchers are notorious for not letting people on their property to look for plants. If someone with governmental clout determined that a plant or animal that lived on a rancher's land was in danger of extinction, regulation might be passed to restrict the use of that land. It is in their interest to not let anyone look for what may or may not be present. Besides, who cares about a cactus? I'm sure there are horror stories from their side of the fence also. So, a lot of times a population of plants may be calculated from the material found from the road to the fence and what can be seen from the fence. Cattle often like to congregate near the fence to make faces at the passing traffic, so along the fence line the ground is well pounded. Most cacti grow up in the protection of some rocks or vegetation to shield themselves from the sun and weather related hazards and also to hide themselves from predators. As larger cacti mature they no longer need the protection they did as juveniles. Small cacti like to keep the bond of a rock, bush, tuft of grass, or something to make themselves less noticeable or create an obstacle to deflect a foot. Domestic animals, with no predators and an augmented food and water supply can really damage cactus habitat. Sure do taste good though!!!
I started to look into the plant's availability in the cactus collecting hobby. The plant is very common in cultivation. And here's why. Beautiful spination, nice pink flowers and a long flowering period, easy to grow and easy to propagate from seed and cuttings and it does not get very big makes this Texan popular with collectors. One of my plants looks like a small stack of shredded wheat and I know someone who has one that has brilliant white, heavy spines, (who promised me a cutting). The flowers are easy to pollinate and produce around thirty seeds per fruit. On a trip to a cactus wholesale nursery last summer I saw that they had a table around twenty feet long and about three feet wide filled with these plants. So maybe scarce in the field, but common in the pot, these are cactus that you would be happy to have in your collection.
Fred Gaumer
************************************************************************
EUPHORBIA: A HARDY PLANT GROUP FROM AFRICA
By Maureen Gilmer
On the Dry Side Monterey Bay Area C&SS
The great botanical diaspora began 125 million years ago. It was that long ago that Africa and South America were a single land mass known as Gondwonaland. Then slow continental drift set in and they broke apart into the continents we know today. Whole plant communities were divided, some drifting away with Africa while the remaining colony stayed home.
Imagine some prehistoric plant, the common ancestor inhabiting that land mass, Individuals that wandered off with Africa became exposed to many of the same brutal climatic conditions as those remaining in America. Increasing desert conditions on both continents forced the ancestor to adapt to survive. This adaptability was contingent on traits in the common gene pool coupled with the occasional crap shoot of a beneficial mutant that lived to reproduce.
In Africa the plants evolved into a group known as the Euphorbiaceae. This is a large family that includes poinsettias. Most interesting are the giant tree like succulent forms common in southern Africa. These unusual succulents are often confused with cacti, but are very different plants. Cacti are exclusive to the New World where they did not evolve into the family Cactaceae until millennia after the Gondwanaland break up.
The progeny of that common ancestor exhibit the same adaptive traits on both continents. They took upright columnar forms or candelabra-like growth to reduce the horizontal surfaces exposed to the sun. For example, Euphorbia in the bush of South Africa appear similar in form to the armed Saguaro cactus of Arizona.
Leaves of both groups are small if existing at all, reducing moisture loss. To compensate for lack of leaves, photosynthesis is carried out through the green surfaces of the stems. Many species of both groups are viciously spiked, a mutual defense against aggressively browsing wildlife seeking scant sustenance in brutally dry climates.
Both groups developed succulent bodies to retain moisture within the plant itself. This compensates for lack of moisture in the root zone during the dry season. When it does rain, this helps them to more quickly absorb copious moisture before it passes through porous sandy soils.
The similarity between euphorbia and cacti is perhaps our most clear example of convergent evolution. This term applies to scores of other plants and animals separated by continental drift, then evolving many of the same traits in isolation.
So how do we tell if a plant is an American cactus or an African euphorbia? Simple. Use a pin to prick the skin of the plant. If the plant bleeds clear or green liquid it is a cactus. If it bleeds milky white latex, then it is a euphorbia or close relative. ( Editor's note)-- A few cacti have white milky sap also. The euphorbia latex is filled with all sorts of caustic chemicals. Most will cause skin irritation on contact. If you are pruning or propagating, its a good idea to wear rubber gloves that wont absorb the latex like cotton or leather. In fact, many African tribes have traditionally stunned fish by adding latex of certain species of euphorbias to pools of water. It is wise to consider all parts of all euphorbias poisonous, so beware if they are to grow where pets and children play.
Like all succulents, the chief enemy of euphorbias is rot, usually caused by inadequate drainage or over-watering. Use porous cactus soil mix rather than standard potting soil to cut down on the risk of rot.
Whether you choose to grow euphorbias or cacti, remember that at one time they both shared a common ancestor. And like siblings in a family separated at birth, they add a new dimension to that age old dilemma of nature vs. nurture. On the internet: go to: www.deserttropicals.com or: wwwcactusmall.com
Maureen Gilmer is a horticulturist and author of ``Water Works'' and 13 other books. You can e-mail her at: mo (at) moplants.com
