Thursday, 28 December 2017

The poinsettia's wild family

Did you know that decorative red poinsettias are related to a plant whose sap can cause allergic reactions on contact? The common poinsettia, Euphorbia pulcherrima (a native Mexican plant, Figure 1), belongs to a family of plants called the Euphorbaceae (you-forb-AY-see-ay; it's fun to say isn't it?). Even though the poinsettia is a rather common plant, many of its brother and sister species are quite exotic - some resemble cacti or tropical plants. Others are of incredible economic importance, including the staple crop cassava (Manihot esculenta) and the castor oil plant (Ricinus communis - yes, the source of the protein called ricin that was used as a poison in Breaking Bad).
Figure 1: A poinsettia. Did you know that those poinsettias that look so nice during the holiday season are related to a plant whose sap can cause allergic reactions on contact?

Among all the famous members of the Euphorbaceae family is a lesser-known cousin called Euphorbia marginata (Figure 2), also known as Snow-on-the-mountain, and sometimes confused with other parsley-like species as described on the Kansas Wildlife Federation page [1]. This plant, like its relatives, contains a white sap inside its stems (kind of like a dandelion). However, the milky-white latex of the Snow-on-the-mountain flower can be highly allergenic to sensitive individuals. This property made it famous when it was widely publicized for interfering in a wedding after the bride transferred some of the plant's sap from its freshly cut stems to her eyes, landing her in the ER on her wedding day [2].

Figure 2: Euphorbia marginata. Also called "Snow-on-the-mountain".
Even now, I sit here next to a poinsettia, cousin to a wedding-destroyer, a TV poison star, and a feeder of millions. If you see a poinsettia this holiday season, I hope it reminds you of the incredible properties that belong to even just a small family of plants. Fantastic!