PLANT OF THE WEEK

Dr. T. Ombrello - UCC Biology Department

 

CROWN OF THORNS

 

Common names:        

Crown of Thorns, Christ Plant, Christ Thorn

Scientific  name:       Euphorbia Milii    (formerly Euphorbia splendens)

Explanation of scientific name:       

Euphorbia  - Euphorbus was the Greek physician of King Juba II (about 50 BC to 19 AD) of Numidia (present day Algeria).  King Juba II was the first person to find a succulent-type Euphorbia, and he named it after his physician.

Milii              - named for Baron Milius, once governor of the island of Bourbon, who introduced the species into cultivation in France in 1821.

splendens  - This older species name means splendid.

The common names allude to the legend that the crown of thorns worn by Christ at the time of his crucifixion was made from stems of this plant.  Interestingly, the stems of this plant are pliable and can be intertwined into a circle.  There exists substantial evidence that the species, native to Madagascar, had been brought to the Middle East before the time of Christ.

The Crown of Thorns is a woody, spiny, climbing succulent shrub with shoots reaching a height of 6 feet.  Leaves are found primarily on young growth, and the plant may defoliate completely if put under moisture or temperature stress.  Subsequent growth will bear new leaves.  The plant flowers nearly all year, and especially in the winter.  The flowers are small and inconspicuous, but the brightly colored modified leaves (bracts) found just beneath the flowers are quite attractive.  Most Crown of Thorns plants in cultivation have red bracts.  A variety with yellow bracts exists, but is not very popular.

The Crown of Thorns is a member of the family Euphorbiaceae (Spurge family).  It is a large family, including such plants as the Poinsettia, Castor Bean, the rubber-bearing plants of the genus Hevea, and the Cassava (from which we get tapioca).  Most members of the Spurge family, for example the Crown of Thorns, exude a sticky white sap (latex) from any cut surface.  The latex is found in special branching tubes called latex tubes.

The latex may produce a severe dermatitis on susceptible individuals, much like poison ivy.  Generally poisonous if ingested in large amounts, the latex undoubtedly contributes to the protection of the plants from herbivores (plant consuming organisms).  The latex of some species has been used for arrow poisons and to stupefy fish for capture.  Euphorbias are not planted near stocked pools since the exudate from broken roots can be fatal to fish.  Despite its poisonous properties, in the past the latex had been used for medicinal purposes.  The common name for the family, Spurge, comes from the same root as purge or expurgate, alluding to its properties if taken internally.

A Crown of Thorns plant in bloom, growing in one of Union County College's greenhouses.