Euphorbia milii, also known as Crown of Thorns, is a trailing shrub. Its many-branched stem ranges from 60 to 100 centimeters in length and 5 to 10 millimeters in diameter, characterized by vertical ridges and densely covered with hard, sharp conical thorns.
These thorns, measuring 1 to 1.5 centimeters long and 0.5 to 1.0 millimeter in diameter, are commonly arranged in 3 to 5 rows spiraling around the ridges. Its leaves are opposite, usually clustered on tender branches, either ovate or elongated spoon-shaped, with entire margins.
The inflorescences, consisting of two or eight groups, are formed in a bifurcated complex array, located in the upper leaf axils of the branches. Enclosed within a bell-shaped involucre with a 5-lobed edge, are several male flowers and one female flower, commonly nestled within the involucre. Euphorbia milii blooms and fruits all year round.
Native to Africa (Madagascar), it is widely cultivated in the tropical and temperate regions of the Old World. Euphorbia milii is easy to cultivate, has a long flowering period, and its red bracts are vivid and eye-catching. It is a highly popular potted plant.
Morphological Characteristics
Euphorbia milii is a trailing shrub. Its many-branched stem, ranging from 60 to 100 centimeters in length and 5 to 10 millimeters in diameter, is characterized by vertical ridges and densely covered with hard, sharp conical thorns.
These thorns, measuring 1 to 1.5 centimeters long and 0.5 to 1.0 millimeter in diameter, are commonly arranged in 3 to 5 rows spiraling around the ridges.
The leaves are opposite, usually clustered on tender branches, either ovate or elongated spoon-shaped, measuring 1.5-5.0 centimeters in length and 0.8-1.8 centimeters in width. The apex of the leaves is round, with a small pointed tip, and the base is gradually narrowed with an entire margin.
The inflorescences, consisting of two, four, or eight groups, are formed in a bifurcated complex array, located in the upper leaf axils of the branches.
Each inflorescence has a stalk measuring 6-10 millimeters in length. At the base of the stalk is a membranous bract, 1-3 millimeters long and 1-2 millimeters wide, with the upper part almost truncated and the edge slightly pointed and red.
The two bracts are reniform, measuring 8-10 millimeters long and 12-14 millimeters wide, with a round apex and a small pointed tip. The upper part of the bract is bright red, and the lower part is pale red, fitting closely to the inflorescence.
The involucre is bell-shaped, 3-4 millimeters high and 3.5-4.0 millimeters in diameter, with a 5-lobed edge. The lobes are lyre-shaped, with fringed long hairs on the upper part, which are inward-curving.
The fruit is a three-angled ovoid capsule, about 3.5 millimeters long and 4 millimeters in diameter, smooth and hairless, and it splits into three segments when mature.
The seeds are egg-cylindrical, about 2.5 millimeters long and 2 millimeters in diameter, gray-brown, with tiny wart-like points and no caruncle. It blooms and fruits all year round.
Distribution Range
Originally from Africa (Madagascar), Euphorbia milii is widely cultivated in the tropical and temperate regions of the Old World. It is cultivated throughout China and can commonly be found in parks, botanical gardens, and courtyards.
Growth Environment
Euphorbia milii prefers a warm, moist environment with abundant sunlight. It can tolerate some shade but not high temperatures. It is somewhat drought-resistant, but cannot withstand cold. Loose, well-drained leaf soil is optimal for its growth.
If the temperature is low during the winter, it may enter a short period of dormancy. It is widely cultivated in both the northern and southern regions of China.
Propagation
Cutting medium refers to the nutritional soil or materials like river sand, peat soil, etc., used for cuttings. Due to constraints, it is often difficult for home gardening to get the ideal cutting medium. It is recommended to use pre-prepared and sterilized cutting medium.
Medium-grained river sand can also be used but should be rinsed several times with clean water before use. Sea sand and river sand from saline-alkali regions should not be used as they are unsuitable for the growth of flowering plants.
The primary method of propagation for Euphorbia milii is via cuttings. Cuttings can be taken throughout the growing season, but the highest success rate is achieved when cuttings are made in May or June.
Select robust branches, about 10 to 15 centimeters long (with 3-4 leaf nodes), wipe off the white latex oozing from the cut, apply wood ash, and let it dry in a cool, shady place for 2-3 days.
Once the cut has dried, insert it into sand, water thoroughly, and then water sparingly. Water again when the soil is slightly dry. The cutting should root in about 50-60 days.
Cultivation Techniques
Choose loose, well-drained leaf soil for potting, and repot every spring. During the growing season in summer and autumn, Euphorbia milii needs plenty of water, so watering should be timely.
Water moderately in spring, about once every 2-3 days. As summer is the growing period, the plant requires sufficient water and can be watered thoroughly daily. The watering regime in autumn is the same as in spring, water thoroughly every 2-3 days. In winter, strictly control watering and keep the soil dry.
As the temperature drops in winter, the leaves fall off and the plant enters a dormant period, so the potting soil should be kept dry. During the plant’s flowering period, the soil humidity should be maintained at a moderate level. It is best to fertilize once a month.
During the growing period, you can use bamboo sticks and lead wires to make various types of supports for binding and guiding the branches to prevent them from falling over. If the temperature is maintained above 15°C during the winter and spring seasons, the plant can bloom continuously.
During this period, if the plant is given sufficient light, the flowers will be particularly bright. If the plant does not get enough sunlight, the flowers will be dull, and if placed in a shaded area for a long time, the plant will not bloom. If the branches become too dense and crowded, the plant can be pruned and shaped before the new leaves sprout in spring.
Pest and Disease Control
Diseases
In seasons of continuous rain, the abundance of rainwater and high humidity, combined with unclean potting soil surfaces, can lead to root rot and stem rot diseases.
Control methods: Root rot can be controlled by watering with a fungicide. Stem rot can be controlled by spraying the stem with agricultural streptomycin or a fungicide. A solution of 50% Daisen, diluted 800 times, can be sprayed once every two weeks.
Prevention should be the main method of disease control. During rainy seasons, the plant can be moved to a place where it won’t get wet. Excess water in the pot should be drained promptly, and the surface of the potting soil should be kept clean. Avoid applying organic fertilizer during the rainy season to prevent diseases.
Pests
The main pests are mealybugs and scale insects.
Control methods: Mealybugs can be controlled by spraying with insecticides such as imidacloprid or pyrethrum. A solution of 50% Omethoate, diluted 1500 times, can be sprayed to kill the pests. If the number of scale insects is small, manual removal will suffice.
Main Value
Medicinal Uses
Euphorbia milii is bitter, cool in nature, and slightly toxic. It can be used to detoxify, clear pus, activate blood circulation, expel water, fight viruses, reduce inflammation, and promote blood circulation. It contains many chemical components, including jatrophol, daphnoretin, and others.
Ornamental
Euphorbia milii is popular for pot cultivation and as a thorny hedge. It is easy to cultivate, has a long flowering period, and its red bracts are bright and eye-catching, making it a highly sought-after potted plant.
Because the young stems of Euphorbia milii are soft, they are often used to bind into various shapes like peacocks, making them exquisite decorations in hotels, shopping malls, and other public places.
Peggie was once a high school mathematics teacher, but she set aside her chalkboard and textbooks to follow her lifelong passion for flowers. After years of dedication and learning, she not only established a thriving flower shop but also founded this blog, “Flowers Library”. Here, Peggie shares the art and science of floristry, offers practical tips for nurturing plants, delves into the captivating histories of various species, and provides insights into running a successful flower shop. She hopes that everyone can take a moment now and then to immerse themselves in the world of flowers. If you have any questions or wish to learn more about flowers, feel free to contact Peggie.
