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Origin and Habitat: Andrahomana coastal region (near the Vinanibe coast), southwest of Taolanaro, South-west Madagascar.
Habitat and ecology: Euphorbia francoisii var. crassicaulis grows on sandy soil on limestone in the open or beneath dense coastal bushes. This variety described by W. Rauh is known from a single collection (1993) is known from a single collection. It is likely to have a very small extent of occurrence and area of occupancy, but further fieldwork is necessary to assess the extent of the population. The place is difficult to access and no other botanists have collected it since. Its habitat is highly threatened by human activities. Major Threat are habitat degradation, fire, habitat clearing for charcoal. This species is highly prized for horticulture.
Euphorbia francoisii var. crassicaulis Rauh
Euphorbia J. 0: 183-187. ills.. 1997
Euphorbia francoisii Leandri
Notul. Syst. (Paris) 12: 161 1946
Description: Euphorbia francoisii var. crassicaulis is one of the most fascinating form among all the small Euphorbia species. It is a dwarf, creeping succulent herb distinguished by var. francoisii by its thicker and larger branches and leaves up to 10 cm long with crisped margins. It was described originally as a variety but it could prove to be a good species with further taxonomic work.
Derivation of specific name: E. francoisii var. crassicaulis was so named for its thick stems (Latin 'crassus', thick; and Latin 'caulis', stem).
Stem: Main branches, terete, up to 30(-50) cm long, and 2 cm in diameter, densely covered by persistent stipules. Stolons creeping, partially buried, producing roots.
Roots: This species has subterranean napiform root, which can be raised for bonsai effect.
Leaves: 5-15 spirally arranged, clustered at stem tips, ovate, 5-10 cm long, and 2-3 cm wide, margins undulate, crisped with prominent white veins above. Stipules bristly, stiff, yellow-brown to red-brown, brushlike at branch apex up to 1 cm long.
Inflorescences. Cyathophylls green, salmon pink, pale reddish-brown or greyish-brown.
Subspecies, varieties, forms and cultivars of plants belonging to the Euphorbia francoisii group
- Euphorbia francoisii Leandri: (var. francoisiii) is a very variable caudiciform shrublet up to 15 cm tall with beautiful leaves coming in a dazzling array of shapes and colours that change with the seasons. Distribution: Andrahomana, SW Taolanaro, Madagascar.
- Euphorbia francoisii var. crassicaulis Rauh: has thicker and larger branches up (to 30 cm and 2 cm in diameter); Leaves up to 10 cm long with crisped margins.
- Euphorbia francoisii f. rubrifolia Rauh: has wine-red leaves and pinkish veins even darker during winter. Seedlings also have red leaves. Distribution: Andrahomana.
Bibliography: Major references and further lectures
1) Urs Eggli “Illustrated Handbook of Succulent Plants: Dicotyledons” Springer Science & Business Media, 2002
2) Werner Rauh, Herman Schwartz “Succulent and xerophytic plants of Madagascar”, Volume 2 Strawberry Press, 1998
3) Rauh,W. 1996. “Euphorbia francoisii Leandri and its new variety crassicaulis Rauh from southwestern Madagascar.” Euphorbia Journal 10: 175-187.
4) Urs Eggli, Leonard E. Newton “Etymological Dictionary of Succulent Plant Names” Springer Science & Business Media, 29 June 2013
5) Haevermans, T. 2004. Euphorbia francoisii var. crassicaulis. The IUCN Red List of Threatened Species 2004: e.T44352A10895073. http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T44352A10895073.en. Downloaded on 12 January 2017.
6) MCNEILL J., BARRIE F. R., BURDET H. M., DEMOULIN V., HAWKSWORTH D. L., MARHOLD K., NICOLSON D. H., PRADO J., SILVA P. C., SKOG J. E., WIERSEMA J. H., & TURLAND N. J. (eds) 2006. "International Code of Botanical Nomenclature (Vienna Code). Adopted by the Seventeenth International Botanical Congress Vienna, Austria, July 2005. Regnum Vegetabile" 146: 1-568.
7) Haevermans T., Rouhan G., Hetterscheid W., Teissier M., Belarbi K., Aubriot X. & Labat J.-N "Chaos revisited: Nomenclature and typification of the Malagasy endemic Euphorbia subgenus Lacanthis (Raf.) M.G.Gilbert" Adansonia 31(2):279-299 · December 2009
8) Don Hunt “Plant of the Month By Don Hunt” Espinas y Flores, The Newsletter of the San Diego Cactus & Succulent Society, Affiliated with the Cactus and Succulent Society of America,Volume 48 Number 9 October 2013
Cultivation and Propagation: This species is a particular favourite of caudiciform plant enthusiasts. Cultivation of this plant is the same as that for the other tuberous varieties of Euphorbia from tropical areas (Madagascar, and central Africa) , but it is not the easiest of all caudiciform Euphorbias. It is particularly prone to rot if left cold and damp while dormant. As the plant ages, it develops a nice caudex, and can be used to make extremely attractive bonsai.
Growth rate: It is a slow growing species and tubers take many years to enlarge.
Caudex exposure: The remarkable tuberous rootstock (caudex) is usually raised above the soil line so that this can be seen and more readily appreciated. The plants raised from cuttings produce a bunch of tangled tuberose roots, while seed raised plants produce a more rounded tuber with age. For best results the tuber must be exposed only when plans become mature enough, usually after several years (8-12 or more years) of underground growth, as the exposed caudex will no longer increase in size once it has been lifted above the soil line. In very old plants, the tuber can achieve massive proportions, so keep a plant for many years to grow an unusually large caudex.
Soil and pots: It likes pots with generous drain holes, needs a very airy potting medium which mainly consists of non organic material such us clay, pumice, lava grit, and only a little peat or leaf-mould, seeing that the main trunk is planted with the majority of the roots below the caudex line. It's rare that it will use the upper third of its soil and often this area serves like a mulch or support for the stem.
Fertilization: Need a perfect fertilizer diet in summer. Use preferably a cacti and succulents fertilizer with high potassium content including all micro nutrients and trace elements or slow release fertilizer.
Exposure: This plant has an excellent heat tolerance, and need full sun to light shade exposures, but can tolerate shade. However shade grown plants will tend to produce fewer, and etiolated growth (weak, gangly stems with unusually long internodes, and generally paler green coloration). The colour of this plant is much more marked if grown in full sun. But if it is possible to keep the growth of this species compact, with denser, shorter stems of a more uniform length (rather than looking weedy) such plants can be outright attractive.
Watering: Water regularly during the active growing season. No water should ever be allowed to stand around the roots. Keep almost completely dry in winter. Even though the swollen caudex ensures a long lasting water reserve making it very tolerant of under watering, this euphorbia is difficult, turning immediately to mush when over watered, or watered out of season. Care must be given in watering, keeping them warm and wet while growing, and cooler and dry when dormant.
Hardiness: Tender. Euphorbia francoisii does not require cool temperatures for its growth cycle or flowering as some of the cactus and crassula species do, and it has not an apparent dormancy period but periods where the emergence of new leaves stops and older leaves wither and drop. This spurge can be difficult to get it to look its best without a good amount of heat and sun and so it is only really suited to the tropics (USDA Zones 10-11). Keep the plant cooler in winter, but maintain the light as bright as you can so that any growth which it may produce at this time will not be etiolated. It can be grown outdoors in the summer months to benefit from direct exposure to light, and especially exposure to high summer temperatures. Protection in a warm greenhouse in the middle of the winter will greatly increase the survival rate.
Rot: Rot is only a minor problem with Euphorbias if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much. It is very unlikely to lose this plant from root rot from excessive water.
Maintenance: Re-pot every two years and trim off the dead 'arms'.
Known hazards: The latex/sap is poisonous and can cause skin rash, itching and general discomfort, and they should be handled with caution, particularly when pruning.
Propagation: The plant can be reproduced by seeds or cuttings. The seed will loose viability in storage, and may not be viable the following year, so the seed should be planted as soon after harvesting as possible. Germination usually occurs within about a week or two. If you remove an offset, remember to let it dry for some days, letting the wound heal (cuttings planted too soon easily rot before they can grow roots). Lay it on the soil and insert the stem end partially into the substrate. Try to keep the cutting somewhat upright so that the roots are able to grow downward. It is better to wash the cut to remove the latex. The newly planted stems take a few weeks to establish, and then start growing. Some plant form a perfectly symmetrical caudex when grown from seed. If a caudex is produced from cutting it is often distorted.
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