here is a short background information about my plant specialization:
Crown of Thorns
Scientific Name: Euphorbia milii var. splendens Des Moul.
Synonym: Euphorbia splendens
Kingdom Plantae – Plants
Subkingdom Tracheobionta – Vascular plants
Superdivision Spermatophyta – Seed plants
Division Magnoliophyta – Flowering plants
Class Magnoliopsida – Dicotyledons
Family Euphorbiaceae – Spurge family
Genus Euphorbia L. – spurge
Species Euphorbia milii Des Moul. – christplant
Variety Euphorbia milii Des Moul. var. splendens
The family Euphorbiaceae is large with about 8,100 species found throughout the world, excepting the Arctic region. Euphorbia itself is a very large genus with over 2000 species. They are characterised by having a milky latex which can cause burns and indeed some may be carcinogenic. The xerophytic species most often have spines and our plant this month - Euphorbia milii var splendens - is no exception. Surprisingly, since it does not need too much watering and, especially the fact that it flowers most of the year, but particularly in the winter months, it has become a cherished house plant for sunny dry situations.
Euphorbia milii var splendens, commonly called Crown of Thorns, is a straggly, spiny shrub bearing bright red bracts and, given a chance, will grow to 2m. Euphorbia milii was named by Des Moulins in 1826 and, while not a succulent, can withstand long dry periods when the plants will shed their leaves. The stems are furrowed and furnished with stout, tapering spines about 2cm long. The leaves occur at the top of the shoots and the branched inflorescences grow from the leaf axils. The variety splendens is simply a larger form than the species itself and occurs naturally. In fact there is considerable variation in the wild in south-west Madagascar and several have been named, including a yellow flowered form, also grown for the pot plant industry.
Of course, the related Poinsettia - Euphorbia pulcherrima - from Mexico, is a major player in the Christmas pot plant industry. These will be on sale from the Friends in December.
Many of the African species of Euphorbia have developed in parallel evolution with the Cactaceae of the Americas. This can be seen in the two borders of the Xerophytic (Succulent) House. (The information board explains the details.) Euphorbia milii var splendens has been pot grown at the Garden for many decades and was planted in the African border when the glasshouse was redesigned about 20 years ago.
Euphorbia milii var splendens demands a bright, sunny situation and, while it can withstand temperatures as low as 45'F (7.5'C), it is best not to let the temperature fall below 50'F (10'C). A well drained compost is essential, for the roots will not tolerate soggy conditions. In fact the plants are better kept drier in the winter time.
Summer cuttings of the current years growth taken about May or June will root in heat. When taking the cuttings it is best to dip the cut ends in charcoal to stop the latex flow before inserting into a sandy compost.
Euphorbia milii var splendens is growing in the Xerophytic House on the right at the entrance from the Corridor.
Mitchell Bob, Euphorbia milii var splendens, Retrieved August 7, 2008, from http://www.st-andrews.ac.uk/~gdk/stabotanic/nov05pom.htm