The Crown of Thorns is probably one of the most under used plants around. And yet it's probably one of the easiest to care for and nearly always has colour on it.
Euphorbia milii is a nice succulent plant native to Madagascar. It also goes by the name Christ Thorn, Christ Plant or Crown of Thorns since it's stems are covered in dense spines. Legend has it these plants were introduced to the Middle East in ancient times and is associated with the Crown of Thorns worn by Christ. One look at the stems and you can, no doubt, see why. Luckily, the spines are not nearly as sharp or painful as those of a cactus.
It's in the spurge family so it's related to plants like the Poinsettia, Castor Bean, Pencil Cactus, and a slew of other perennials. Like other plants in the Euphorbia/Spurge family, it contains a milky latex sap which can cause some skin irritation and will cause gastrointestinal upset. The sap is technically considered poisonous, but in such large amounts there would be no practical way of ingestion to the point of causing actual toxicity. The family name of Spurge has it's origins similar to "expurgate" referring to what happens when the sap is taken internally. Ingestion will cause major irritation often leading to vomiting. Most animals and pets avoid this plant both due to it's spiny stems and also the awful taste of the sap. Like other spurges, the flowers are technically inconspicuous and dull, but they produce a series of modified coloured leaves called bracts which are used to attract pollinators. These bracts can be red, pink, yellow, or variations thereof. Looking closely, you can see the tiny true flower in the centre of the coloured bracts.
As a houseplant, it has nearly no other equal. I usually refer to them as "The Other Succulent". They're more tolerant of drying out than most houseplants, though not quite to resiliency levels of cacti or true succulents. They prefer to not quite get totally dry or they will shed some of their leaves. Like many other succulents, they're also sun lovers. When a Crown of Thorns is kept in a bright and sunny spot, it flowers and produces bracts nearly indefinitely. This makes it a very valuable succulent, indeed, but lending that extra colour not always offered by other succulent plants. Because of the nature of their sap, very few pests bother these little plants. They make an excellent beginner houseplant and office desk plant with sufficient lighting.
Although the native Euphorbia milii can get quite large with very long stems devoid of leaves, newer hybrid varieties are much more compact and well behaved. These compact varieties grow very slowly which adds to their appeal in the home where we really don't want our plants to get overly floppy.
Euphorbia milii quick tips:
- Put in the brightest and sunniest spot you can find and it will continue to produce colour
- Allow the soil to dry-down somewhat between watering, preferably not to the completely dry point
- Water thoroughly when dry - it's best to place them in a saucer, water well, and let them sit in the saucer for about 30 minutes then drain the excess water
- You can plant them with other succulents as part of a dish-garden
- Fertilize regularly with a low dose of food and be sure the soil is moist prior to adding food so you don't shock the roots