Keep on reading the article if you want to know how this story goes (…)

Well, if on the one hand, I would still like to see my expression immediately after having smelled that flower, on the other hand, the joke of that nurserywoman has forever imprinted in my memory my first encounter with a Stapelia (in this case a Stapelia gigantea), but above all with its flower, as beautiful and showy as it’s terrible, disgusting in terms of smell. And on the other hand, this is the main characteristic of almost all the plants belonging to the Asclepiadaceae family: their flowers, be they the small ones of the Piaranthus or the huge ones of certain Stapeliads, have a terrible smell. The smell they give off is that of rotting flesh, in particular, and there’s a specific reason Nature has chosen this for them.

Let’s see why this large family of succulents is condemned to produce flowers with beautiful shapes, incredible streaks and yet terribly smelly. Let’s get to know better the Asclepiadaceae, the various genera belonging to this family native to Africa and let’s learn how to correctly cultivate its species.

Origin and provenance

The Asclepiadaceae family includes about two thousand species and almost 250 genera, a quarter of which are succulents. In the last years, the classification has changed the Asclepiadaceae family to a subfamily included in the Apocynaceae family, but for convenience and brevity, I will write here of “family” referring to the Asclepiadaceae. First of all, it must be said that not all Asclepiadaceae are succulent plants: in this large family, you can find herbaceous plants, leafy plants, bushes, trees and even lianas. The origin of these plants is mainly African, in particular the temperate, tropical, subtropical and desert regions of the African continent. However, their distribution is not limited to Africa: some genera of the Asclepiadaceae family are native to the American continent, others to the Arabian Peninsula to China, and others to Oceania. Finally, two species are of European origin: Caralluma mumbyana and Caralluma europaea, actually native to the extreme South of Italy (Lampedusa) and North Africa (Morocco, Tunisia, Libya).

Maps with the distribution of succulents in the world.

Flowers are of various sizes and go from the few centimetres of Hoya to the huge ones, up to about thirty centimetres, of Stapelia gigantea, but they are always star-shaped, with five sepals and five petals joined together at the base.

The most known and cultivated genera

As for the lovers of succulent plants, the most appreciated and cultivated Asclepiadaceae belong to the group (or “tribe”) of Stapeliae. In this group are included: the genera Stapelia, Caralluma, Duvalia, Echidnopsis, Frerea, Hoodia, Huernia, Orbea, Piaranthus, Pseudolithos, Tavaresia, Whitesloanea. Among the Asclepiadaceae not belonging to the Stapeliae group, more cultivated by the lovers of succulents, there’re Hoya (the epiphytic plant with “wax flowers”), Ceropegia and Fockea. The species of the group Stapeliae are almost all characterized by fleshy stems and tufty posture. In some cases, they develop proper succulent branches, in others, they form rounded or short-cylindrical “articles” (as with the genus Piaranthus). In other cases, the stem is like a sculpture, similar to a small monolith or a rock (e.g. Pseudolithos and Whitesloanea). Totally different is instead the posture of Hoya, which develops very long stems from which fleshy, thick leaves come out. Ceropegia has a similar appearance, while Fockea forms big brown caudex (caudex is basically the thick and wide stem) from which long branches with small, not fleshy, leaves of an intense green colour branch out.

Why do the flowers smell?

Let’s start by saying that not all the flowers of the Asclepiadaceae deserve the nickname of “carrion flower” or “stinky plant”, with which Stapelia flowers are usually associated. Many flowers of plants belonging to this family produce perfume or ugly odour, as in the case of Hoya, whose flowers grouped in clusters have a beautiful shiny appearance, perfect, to be defined as “of wax”. Same for the flowers of Fockea, not very evident and without any particular smell or fragrance. They certainly deserve the definition of “carrion flower” many other genera, almost all belonging to the group Stapeliae, particularly the flowers of Stapelia and those of Piaranthus.

Why this curse? Why do such showy, beautiful and colourful flowers give off the smell of rotting flesh? Simply because the pollinating insects of these plants are flies, and it’s to these insects that these plants rely on to multiply. The most emblematic example is Stapelia hirsuta (the plant you can see above, under the title), which produces large star-shaped flowers, blood-red in colour to recall the colour of meat, and smelly, just like rotting flesh. The flies are strongly attracted to it: they pass from one flower to another just as bees do with any flower, pollinate the Stapelia and lay their larvae inside the flower, which, however, drying up, will prove to be a deadly trap for the larvae themselves, condemned to die inside the closed flower. If the smell of rotten meat is typical of the species of the genus Stapelia, many other Asclepiadaceae produce smell even if with different “fragrances”, as in the case of Piaranthus, Orbea and Pseudolithos, just to mention a few. Finally, as for the flowering period, almost all the Stapelia‘s plants group flower in autumn until the beginning of winter. An element, this one, which can interest those who want to enjoy blooming for almost the whole year, if they place side by side to the cultivation of Cactaceae the cultivation of Asclepiadaceae.

Cultivation regime

Staying in the Stapeliae group, which is of interest to succulent growers, it should be noted that Asclepiadaceae need a very different cultivation regime than the one effective for Cactaceae. Firstly concerning the minimum winter temperatures, which should be kept under control so that Asclepiadaceae do not go down 7-8 Celsius degrees. Fundamental, as for cacti, is that the plants remain in full dry soil from October to the end of March. If we see that the stems begin to lose too much turgidity, we can give little water on sunny days. I recover my Asclepiadaceae in an unheated cellar, with minimum temperatures between 6-8 degrees. At night, in the greenhouse, it can go down to 0 degrees, and I prefer not to risk it. Even about the exposure, the differences with most of the Cactaceae are of relief. The Asclepiadaceae of the group Stapeliae do not go exposed to the direct sun if not in the morning. From when the sun gets warmer, around midday, the plants should be sheltered in a greenhouse or by a shading net or, again, placed behind plants and shrubs that can give them shade. If kept in too much sun, Stapeliae suffers, slow down their vegetation and become extremely red. In summary: give them lots of light but not direct sun.

Watering should be done only from the end of March to the end of October but without exaggerating because these plants are sensitive to water stagnation and environmental humidity. Watering should be reduced, therefore, and the soil should be very draining. About the substrate, some grow Asclepiadaceae succulents in mineral soil, without organic (peat or humus), mixing pumice, zeolite, akadama, gravel, etc… Other growers keep them in only pumice, which promotes rooting and retains excess water by releasing it little by little. I’ve been growing these plants in the usual mix of equal parts peat, pumice, and lapilli, but I’m gradually switching to pumice alone, which requires more frequent fertilizing because it doesn’t provide much in the way of nutrients. Alternatively (as I did in the video at the end of this article), you can use a substrate made of pumice with the addition of a few humus (10%) and not much sand to give a minimum of nutrients and to add a good part to the compost, which with only pumice would be too coarse.

The soils to use with succulent plants.

In his book, Giuseppe Lodi advised to grow the Asclepiadaceae “in rather oily soil, but very permeable and sandy at the top”. He suggests it just to ensure that the collar does not remain wet for too long, being easily subject to rot. Always noted Lodi: “It is advisable to put a rich layer at the bottom (more leaf mould than sand and soil), then an intermediate layer with more sand and an upper one even more sandy” (Giuseppe Lodi, “Le mie piante grasse” – Edagricole).
For the rest, the cultivation rules indicated for most succulents are valid: as much air as possible and sparing fertilizations with specific products for succulents only during the vegetative season.

Main adversities

Collar rot and cochineal mealybug are the main problems in the cultivation of succulent Asclepiadaceae. To preventing rottenness, it’s advisable to moderate watering, use correct substrates and give as much air as possible to our plants. Against mealybug, the same cares are more or less valid since proper cultivation is the best prevention. Also, as a preventive measure, it’s possible to use specific products in particular periods. A few passes of copper oxychloride by spraying the stems at the end of the growing season and just before spring, for example, and Neem oil, again by showering during the warmer months (here a specific article). Against mealybug, some recommend inserting two or three balls of mothballs in the soil, a little deep. I have never tried this method, but I have heard of it several times.

Propagation

The multiplication of Asclepiadaceae can be done, as always, by seed or by cuttings. Seeding is necessary for those kinds of plants that do not branch, such as Trichocaulon and Whitesloanea, while cutting is the fastest method to reproduce genera such as Stapelia, Orbea, Caralluma, etc… It’s enough to cut a branch with a sharp cutter, let it dry for a couple of weeks in an airy place, sheltered from the sun and then place it on pumice with a superficial layer of sand. At that point, it’s possible to nebulize the stem and the substrate’s surface once every two or three days, thus favouring the rooting of the cutting. Obviously, reproduction by cuttings must be done during the vegetation period, therefore from late spring onwards and never in winter. Moreover, to avoid rottenness, it is better to sprinkle with copper oxychloride powder both the mother plant in the point where the branch has been cut and the cutting itself.

 SUBSCRIBE TO THE SITE  – If you liked this article, subscribe to the site to have access to all the contents for one year or three months depending on the formula you choose. Here you will find terms and conditions.

 SUBSCRIBE TO THE NEWSLETTER  – If you want to receive the free newsletter every time new content is published (even if you have not subscribed to the site), fill in the fields at this link!

Repotting of Asclepiadaceae: the video

© The texts, videos, photos and graphic elaborations of the site “Il fiore tra le spine” are original material and are covered by copyright. It’s forbidden to reproduce them in any way.

L'articolo The Asclepiadaceae family: African succulents with beautiful but… smelly flowers proviene da Il fiore tra le spine.

Let’s deepen our knowledge of the Lithops genus in this article, in which we will also see the particular cultivation regime that these plants need in order to live in the Northern hemisphere. (…)

Description

Among the genera belonging to the Mesembryanthemaceae (or Aizoaceae according to the classification currently accepted by the majority of researchers), that of the Lithops is certainly among the most full-bodied in terms of number of species and at the same time among the most appreciated in cultivation. These are dwarf plants, ie small even in adulthood, coming from semi-desert areas of southern Africa, in particular from the areas of Namibia and South Africa. The “living stones” are called by Giuseppe Lodi in his splendid volume “Le mie piante grasse” (Edagricole). And “living stones” or “living rocks” is the definition to which we often see these plants associated, due to their flat, rounded appearance, with colors and superior design capable of perfectly reproducing small stones, with which in nature they are camouflage on the soils of origin. On the other hand, the same scientific name indicates this characteristic, being derived from the Greek lithos, i.e. pebble/stone, and opsis, i.e. “appearance”.

Each plant is formed by a pair of fleshy leaves, joined at the base of the short conical stem and clearly separated by a slit at the apex, which is flat and with rounded edges, overall ovoid in shape. If along the sides the stem and the leaves have a uniform colour, which varies from species to species from green to reddish to grey/blue, the upper part of the leaves, i.e. the one that receives light and stores it for photosynthesis, is covered by thin veins (in some cases there are punctiform spots) and rich in shaded colours, these too vary according to the species. The stem is almost completely underground: the plants emerge from the ground for a few millimeters and the upper face of the two leaves has a sort of “window”, i.e. an area without chlorophyll and therefore able to filter the light and let it penetrate inside the plant. The root system develops at the end of the cone which forms the stem and branches off from a fleshy root, dividing into not particularly long peripheral roots. Overall, however, between the stem and the root system, the plant grows several centimeters deep and it will therefore be a good idea to use deep pots for cultivation.

The flowers

Lithops blooms are never abundant: generally one or two flowers at a time, but if we grow these plants in bowls, side by side, we will have a beautiful spot of color during flowering, which in our latitudes (Northern hemisphere) occurs in autumn roughly between the end of October and the beginning of November. The flowers emerge from the crack between the two leaves and are always white or yellow, reminiscent of daisies and open in the afternoon. In this regard, what Lodi notes is interesting: “The difference in color of the flowers is often accompanied by a difference in the shape of the bodies. In the very young plants of Lithops with yellow flowers (…) the fissure between the two lobes does not cross the entire upper face; in those with white flowers (Leucolithops) the fissure crosses the entire upper face” (Giuseppe Lodi, “Le mie piante grasse”, ed. Edagricole).

The moult of the leaves

A peculiar feature of these plants is the moulting of the leaves, which can occur in variable periods (in any case during the winter in the northern hemisphere) depending on the species and age of the plant. It is through the moult that the plant, in fact, is “reborn” and perpetuates itself. The old leaves dehydrate to get completely dry; at the same time, a new pair of leaves begins to form from the buried stem. As they grow, the new leaves will literally break the old ones, which will have collapsed in the meantime. Once the new ones have formed, the old leaves will dry out completely and can be detached by simply pulling them gently with your fingers (operation to be done only when the leaves are completely dry!). Of fundamental importance is not to water the plant while the moult is in progress. In this phase the Lithops do not absorb water and the new leaves feed on the liquids accumulated inside the stems. Watering would be equivalent to soaking the soil so that it remains wet for a long time (in part because the moult takes place in winter and the humidity does not evaporate due to the low temperatures, in part because in this phase the plant does not drink), with consequent triggering of the rot that would lead the plant to death.

Cultivation

The cultivation of these plants requires particular and distinct precautions compared to those required by cacti or other succulents. Overall, however, Lithops are not difficult to grow, provided you know their needs.

The soil must be very poor and draining. You can use a third of clayey field earth mixed with fine sand to which we will add a third of pumice and a third of quartzite (that for aquariums is fine). Alternatively, we can reduce the part of clay a little to add a small organic component (peat or earthworm humus). Lodi advised, for these plants, a substrate composed of three parts of sand, two of clay and one of leaf mold. As far as exposure is concerned, Lithops need plenty of light, even direct sun if they are used to it, for most of the day. In this way they will maintain the compact shape of the stem and the leaves will not lengthen, ending up protruding a few centimeters from the soil, as happens in incorrectly cultivated specimens.

The waterings can be abundant but it is good to reduce them and wait for the substratum to dry completely between one watering and another, also because these succulents are particularly sensitive to humidity and can rot easily if the soil is not correct. On the contrary, like many other Mesembryanthemaceae, they tolerate long periods of drought without problems, so in case of doubt, the advice is always to not water and let more time pass before giving water.

As a rule, let’s say that in the Northern hemisphere the Lithops are watered exclusively from May to all of October, reducing the watering in the central months (July and August) to suspend them completely in November: in fact, they should be watered from when the moult is completed until the plants slow down to face the winter. During the winter months it is not entirely certain that these plants go into stasis, as happens for example with cacti. It is probable that, even if they stop absorbing water, the plants work on moulting in the underground part. No problem with low temperatures: if kept perfectly dry from the end of October, Lithops can winter even at five or six Celsius degrees below zero.

Reproduction

Lithops can be reproduced by cuttings or by division of the tufts, but the most used method is sowing, which follows the rules common to cacti. The seeds are rather small and the undertaking can prove inconvenient for the less experienced, but overall it does not present particular difficulties.

Species and varieties

There are dozens of species attributable to the genus Lithops and even more varieties. Only an expert eye is able to distinguish one species from another or a variety from a cultivar. The design on the leaf surface can help, as well as the color of the plant and its nuances, but the undertaking, for those who are not experts, remains quite difficult. Among the most common and widespread species we should mention the aucampie, the karasmontana, the lesliei, the optica and the pseudotruncatella. As for the colors you are spoiled for choice and there is no shortage of bright green Lithops (once very difficult to find) or blue, gray, brick red or purplish.

 SUBSCRIBE TO THE SITE  – If you liked this article, subscribe to the site to have access to all the contents for one year or three months depending on the formula you choose. Here you will find terms and conditions.

 SUBSCRIBE TO THE NEWSLETTER  – If you want to receive the free newsletter every time new content is published (even if you have not subscribed to the site), fill in the fields at this link!

Correlated articles

Succulent plants
Substrates for cacti and succulents
Watering succulents
Classification of succulents

© The texts, videos, photos and graphic elaborations of the site “Il fiore tra le spine” are original material and are covered by copyright. It’s forbidden to reproduce them in any way.

L'articolo Lithops: peculiarities and cultivation rules of the so-called “stone plants” or “living stones” proviene da Il fiore tra le spine.

You can deepen the knowledge of Euphorbiaceae in the following article, with description, images, curiosities and cultivation techniques specific to this plant family. (…)

Historical notes

The first succulent Euphorbia was discovered between 25 B.C. and 18 A.D. by King Juba of Mauritania (present-day Morocco). The name given to the family has curious origins: after having found out one of these plants (perhaps E. resinifera or E. officinarum) on the Atlas Mountains, it seems that King Juba gave it the name of his doctor, Dr Euphorbus, drawing inspiration from the translation of the term, which means “well-fed”. Some non-juice species of Euphorbia were instead known for years, since the time of Ancient Greece and were called “Tithymalus“. The two names co-existed until the time of Linnaeus, who combined them under the name Euphorbia in 1753. Nowadays the name Tithymalus survives but only indicates a subgroup of Euphorbia.

Problems with the classification of plants and the distinction into families? Here you’ll find a perfect article for you.

Features

The appearance of Euphorbia, as I said, can be extremely variable. The common denominator of this family, however, is the sexual organ of the plant. In this case, we do not speak of “flower” but of “cyathia”. These are very specialized floral structures and at the same time very different from flowers as we understand them. The cyathiazians are, in fact, small in size and can be unisexual or bisexual. Basically, inside unisexual cyathia, there is a single female flower or some male flowers, while in bisexual cyathia there is a female flower surrounded by male flowers. This is one of the main differences between succulent Euphorbiaceae and Cactaceae.

Cultivation

Since they come from all over the world, the various Euphorbia species have very different cultivation needs. Even staying in the “field” of succulent Euphorbias, you can have plants that need a lot of light as well as plants that adapt well to reduced exposure. Some Euphorbias can withstand prolonged drought well and others that do not withstand long periods of dryness. Some Euphorbias can withstand low temperatures (even below zero) and Euphorbias that do not tolerate low temperatures below 7-8 degrees.

For my choice (and not to deviate too much from the regime of cultivation of my cacti) I cultivate only Euphorbia able to tolerate the cold. I have specimens of E. obesa, E. enopla, E. ferox, E. meloformis, E. canariensis, E. resinifera. I have also tried to grow E. candelabrum but with poor results because of its poor tolerance to low temperatures. As for the species I grow, I don’t have particular problems: they are quite resistant plants and can be cultivated more or less like cacti. I keep them in soils a bit richer in organic matter than cacti, both based on the classic lapillus, pumice and peat, and on clay and inerts such as pumice, sand and river gravel. I water them only during the growing season, from April to September, leaving them completely dry in the remaining months of the year, and I keep them in greenhouses not shaded, therefore with good exposure.

Soils for cactus and succulent plants: all my “recipes”.

Euphorbia obesa

And now just two words about Euphorbia obesa, much appreciated and widespread among succulent lovers. It can be said that this plant is the succulent par excellence: in its juvenile stage, it’s perfectly round, “fat”, in fact, without thorns and with a harmonious look, embellished by the streaks on the surface of the stem. Growing up, it tends to assume a short cylindrical bearing while maintaining the thick stem inside which it stores its water reserves.

Reproduction

Euphorbias can be easily reproduced both by seeding and cutting in the spring months. In this second case, it is good to be careful when cutting because many species contain latex that can be toxic in some cases. To stop the release of latex, once cut a branch of Euphorbia (wearing gloves!), you can immerse it in water for a few minutes, then let it dry for at least a couple of weeks and bury it in pumice or sand until it has taken root. The cuttings can then be repotted into suitable soil.

How to propagate cacti and succulents from seed: the whole procedure.

Curiosity

Some Euphorbia species are very usual and are easily found on the market, especially at certain times of the year. What is commonly called “poinsettia“, in fact, is nothing more than a Euphorbiaceae (E. pulcherrima). In the winter period, following some cultivation expedients (in particular after having kept it almost in the dark for a few months) this plant produces deep red apical leaves, becoming very showy and decorative. Another very usual species is E. milii, commonly called “Thorn of Christ”. It’s a Euphorbia with thin stems covered with thorns, at the apex of which sprout colourful and very decorative small inflorescences. There are no particular historical findings, but this plant owes its common name to the legend according to which the crown of thorns placed for mockery on the head of Christ was made by weaving shrubs of this Euphorbia.

 SUBSCRIBE TO THE SITE  – If you liked this article, subscribe to the site to have access to all the contents for one year or three months depending on the formula you choose. Here you will find terms and conditions.

 SUBSCRIBE TO THE NEWSLETTER  – If you want to receive the free newsletter every time new content is published (even if you have not subscribed to the site), fill in the fields at this link!

© The texts, videos, photos and graphic elaborations of the site “Il fiore tra le spine” are original material and are covered by copyright. It’s forbidden to reproduce them in any way.

L'articolo How to cultivate Euphorbia: tips to best care for these succulents loved by all the cactophiles proviene da Il fiore tra le spine.