Small, succulent Euphorbias
(This week Succulentophile gives way to an article by Peter Bangayan.)
The genus Euphorbia is just one of 300 genera belonging to the family Euphorbiaceae. Euphorbias generally have small, insignificant flowers and most exude a milky sap, which in most plants is highly poisonous. The genus Euphorbia contains some 2,000-plus species, which include the common poinsettia, often seen during the Christmas holidays and the common and colorful Euphorbia millii and its hybrids from Thailand, which are widely used in landscaping. Most succulent Euphorbias come from the African continent, the island of Madagascar and India.
Many succulent Euphorbias are quite easy to grow in our climate because a large number of them come from tropical Africa in places such as Madagascar, Ethiopia, Kenya, Mozambique, Sudan, Tanzania and Zaire. These countries generally lie near the equator, as does the Philippines, and they have almost the same temperature range except that we have a much more humid climate. Succulent Euphorbias from South Africa are much harder — if not impossible — to grow in our climate, because they require cool dry nights and have resting periods during South African winter months, where they become dormant during the cold and dry season. These include the medusa-head type of Euphorbias such as E. caput-medusae, E. inermis or E. flanaganii. Imported medusa heads usually survive for a few months or years in our climate but will eventually succumb to rot in our constant hot and humid environment.
Tropical African and Madagascan Euphorbias come in many sizes and shapes, from giant, tree-size branching Euphorbias such as E. antiquorum and E. lactea, which are quite common plants that we see growing in gardens, to small globular or clumping jewels such as E. francoisii, E. decaryi, or E. gymnocalycioides. Growing and collecting the miniature species can be a fascinating hobby. They do not take up a lot of space; just provide the right environment and they will flourish and provide you with endless fascination and satisfaction. A word of caution is in order, though: the milky white sap of most all Euphorbias is highly toxic; wash your hands after working with them as touching any sensitive parts of your skin such as the areas in and around your eyes and lips can cause a painful burning sensation in the area. If this should happen wash the area immediately with warm water and soap. It is said that the sap of another succulent, Aeonium lindleyi, can make the burning stop, but unfortunately it is quite hard to grow this plant in our constantly hot and humid climate.
One of the most important things in growing beautiful, small succulent euphorbia plants (or any succulent plant) is to give them sufficient light. Remember that most of them grow in dry, desert-like environments, so that their light requirement is quite high (although some, like Euphorbia decaryi and its relatives, grow under the shade of other, larger plants). A few hours of morning or late-afternoon sunlight are sufficient for good growth. If given good sunlight, they will grow into compact beautiful plants more akin to their natural form. Plants grown in shade can result in straggly, weak, and thin-stemmed growth. Euphorbias are not very particular when it comes to their growing medium; they just need a rich porous medium, which can be a mixture of equal parts garden loam, sharp sand and well-rotted compost. When watering succulent plants, the general rule is to water the plants when the medium has almost dried out (not completely dried up). Water thoroughly. One mistake with beginners is that they water only the surface of the medium and the water does not reach the roots beneath, so that the plants become shallow-rooted or the lower roots die, which can sometimes lead to bacterial rot.
Euphorbias are very resistant to pests and diseases, especially when they are grown well. Common Euphorbia pests are scales, aphids and mealy bugs. These sucking insects can be eliminated with a proprietary insecticide; however, precautions must be taken in applying these poisonous chemicals. The more environmentally friendly and safer insecticides such as vegetable oil and detergent-based insecticides can also be very effective against scales, aphids and mealy bugs. Bacterial and fungal rot is one of the most common diseases that can afflict succulent plants. If the rot is detected early, the rotted portion should be cut off with a sterilized knife or blade to prevent it from spreading. Many commercial growers apply powdered fungicide to the cut portion of the plant. As a reminder, fungicides are very poisonous when inhaled or absorbed through the skin, so if you do not have the proper protection, I would not recommend this. Some growers use flowers of sulfur on the cut portion, which can act as a sealant and fungicide to prevent further infection from entering into the open wound. If the rotted portion is the roots, unpot the plant, cut out all the infected roots and dry the plant in a bright, well-ventilated area. Wait for the cut portion to form a callus before planting in a fresh sterilized medium. Any plastic or clay container is suitable for growing Euphorbias; just remember that plastic containers are not porous so they will take a longer time to dry out compared to clay containers of similar size. Containers, if properly chosen, can accentuate the beauty of the plants.
There are many species of dwarf Euphorbias that one can grow. Some of the easier-to-grow plants include Euphorbia decaryi and its varieties and forms. Similarly growing species are Euphorbia cylindrifolia and the very variable Euphorbia francoisii. These small plants have creeping stems or stolons with small succulent leaves growing at the tips of the stems. Globular types include the common Euphorbia obesa, Euphorbia meloformis, Euphorbia valida and the beautiful Euphorbia gymnocalycioides, just to name a few. Some clumping stem types that clump at the base are the miniature Euphorbia dichroa and Euphorbia petricola.
Euphorbias can be used as bonsai subjects. Plants such as Euphorbia claviflora, Euphorbia groenewaldii, Euphorbia stellata and Euphorbia persistens, which form a large underground stem or tuber, can be raised in cultivation to make them look like old tree trunks. Small branching types with bulbous base stems suitable for succulent bonsai subjects are Euphorbia sakarahensis, Euphorbia beharensis, Euphorbia rossii and Euphorbia gottlebei. These plants hybridize easily and hybrids between these plants and the Euphorbia decaryi group make for interesting plants. One of the rare and endangered Euphorbias is Euphorbia abdelkuri, with stems looking like melted candles. They occur only in the island of Ab Al-Kuri, which lies in the Arabian Sea off the Horn of Africa. Many rare and slow-growing Euphorbias such as Euphorbia horwoodii, Euphorbia sepulta, Euphorbia gymnocalycioides, Euphorbia piscidermis and Euphorbia abdelkuri are usually grafted onto faster-growing plants such as Euphorbia echinus, Euphorbia canarensis or Euphorbia lactea.
Growing dwarf succulent euphorbias can be an interesting and satisfying hobby. They do not need much space and the huge diversity of forms never ceases to amaze. Try to grow plants that adapt readily to our climate and you will be rewarded with beautiful plants.
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For interested plant lovers and hobbyists, the Cactus & Succulent Society of the Philippines will hold a plant show at the Quezon City Memorial Circle from Nov. 21 to 29.
