The poinsettia (; Euphorbia pulcherrima) is a commercially important flowering plant species of the diverse spurge family Euphorbiaceae. Indigenous to Mexico and Central America, the poinsettia was first described by Europeans in 1834. It is particularly well known for its red and green foliage and is widely used in Christmas floral displays. It derives its common English name from Joel Roberts Poinsett, the first United States minister to Mexico, who is credited with introducing the plant to the US in the 1820s; however, there have been recent efforts to rename the flower to its Nahuatl name, "cuetlaxōchitl", due to Poinsett's involvement in slavery and the Trail of Tears. Poinsettias are shrubs or small trees, with heights of . Though often stated to be highly toxic, the poinsettia is not dangerous Klotzsch credited Carl Ludwig Willdenow with the species name "pulcherrima", and the authority is given as Willd. ex Klotzsch. The holotype had been collected in Mexico during an 1803–1804 expedition by Alexander von Humboldt and Aimé Bonpland.
It was known by the common name "poinsettia" as early as 1836, Prior to poinsettia, it was known as "Mexican flame flower" or "painted leaf".
Description
thumb|A full-grown specimen of E. pulcherrima|alt=A cluster of red and green leaves leans toward the viewer on long, bent branches bursting out from a main plant on the base of a rock wall.
thumb|alt=A colored illustration shows the tip of a wild poinsettia branch. The leaves are less densely clustered. Leaves are long and ovate; most are red but one is green, and one is red at the base and green at the tip.|Scientific illustration of E. pulcherrima, ca. 1880
Euphorbia pulcherrima is a shrub or small tree, typically reaching a height of . The plant bears dark green dentate leaves that measure in length. The colored bracts—which are normally flaming red, with cultivars being orange, pale green, cream, pink, white, or marbled—are often mistaken for flower petals because of their groupings and colors, but are actually leaves. Semi-evergreen, they generally lose most of their leaves during winter.
The flowers of the poinsettia are unassuming. They are grouped within the cyathia (small yellow structures found in the center of each leaf bunch, or false flowers). Nothing is known about pollination in wild poinsettias, though wasps are noted to occasionally visit the cyathia. Extrafloral nectaries in E. pulcherrima were first reported by Zimmerman in 1932.
Toxicity
thumb|alt=A newspaper clipping; the headline says "Poinsettia Deadly Says Scientist", while the subtitle says "Carl H. Willing", Horticulturalist and Forester, Brings Grave Charge Against one of Hawaii's Most Beautiful Flowers"|Newspaper headline from the [[Honolulu Star-Bulletin (1913) wrongly alleging that poinsettia is deadly]]
Poinsettias are popularly, though incorrectly, said to be toxic to humans and other animals. In 1944, the plant was included in H. R. Arnold's book Poisonous Plants of Hawaii on this premise. Though Arnold later admitted that the story was hearsay and that poinsettias were not proven to be poisonous, the plant was thus thought deadly. In 1970 the US Food and Drug Administration published a newsletter stating erroneously that "one poinsettia leaf can kill a child", and in 1980 they were prohibited from nursing homes in a county in North Carolina due to this supposed toxicity.
An attempt to determine a poisonous dose of poinsettia to rats failed, even after reaching experimental doses equivalent to consuming 500 leaves, or nearly of sap. Contact with any part of the plant by children or pets often has no effect, though it may cause nausea, diarrhea, or vomiting if swallowed. External exposure to the plant may result in a skin rash for some. A survey of more than 20,000 calls to the American Association of Poison Control Centers from 1985–1992 related to poinsettia exposure showed no fatalities. In 92.4% of calls, there was no effect from exposure, and in 3.4% of calls there were minor effects, defined as "minimally bothersome". It can induce asthma and allergic rhinitis in certain groups of people.
Chemical composition
Pulcherrol and pulcherryl acetate are among the components of its latex. Triterpenes are found in aerial parts of the plant, including its latex and leaves. One such triterpenoid skeleton is being investigated for its anti-Alzheimer's disease bioactivity. Today it is known in Mexico and Guatemala as or simply , meaning 'Christmas Eve flower'. The star-shaped leaf pattern is said to symbolize the Star of Bethlehem, the red color represents the blood shed during the sacrifice of Jesus' crucifixion, and the white leaves represent the purity of Jesus.
Poinsettias are popular Christmas decorations
Cultivation
thumb|Euphorbia pulcherrima in Viherlandia|alt=Many euphorbia pulcherrima flowers, all the same height, growing in a very large cylindrical greenhouse with white walls. A number of growing lights hang from the ceiling.
The Aztecs were the first to cultivate poinsettias. Cultivation in the US began when diplomat Joel Roberts Poinsett sent some of the plants back to his greenhouses in South Carolina in the 1820s. Specific details about its spread from there are largely unverifiable, but it was exhibited at the Pennsylvania Horticultural Society's 1829 Philadelphia Flower Show by Colonel Robert Carr. Carr described it as "a new Euphorbia with bright scarlet bracts or floral leaves, presented to the Bartram Collection by Mr. Poinsett, United States Minister of Mexico." Each year in the US, approximately 70 million poinsettias are sold in a period of six weeks, at a value of US$250 million. In Puerto Rico, where poinsettias are grown extensively in greenhouses, the industry is valued at $5 million annually. There are over 100 cultivated varieties of poinsettia that have been patented in the US.
To produce extra axillary buds that are necessary for plants containing multiple flowers, a phytoplasma infection—whose symptoms include the proliferation of axillary buds—is used. The discovery of the role phytoplasmas play in the growth of axillary buds is credited to Ing-Ming Lee of the USDA Agricultural Research Service.
American industry
Albert Ecke emigrated from Germany to Los Angeles in 1900, opening a dairy and orchard in the Eagle Rock area. He became intrigued by the plant and sold them from street stands. His son, Paul Ecke, developed the grafting technique, but it was the third generation of Eckes, Paul Ecke Jr., who was responsible for advancing the association between the plant and Christmas.
Until the 1990s, the Ecke family, who had moved their operation to Encinitas, California, in 1923, had a virtual monopoly on poinsettias owing to a technique that made their plants much more attractive. They produced a fuller, more compact plant by grafting two varieties of poinsettia together. A poinsettia left to grow on its own will naturally take an open, somewhat weedy look. The Eckes' technique made it possible to get every seedling to branch, resulting in a bushier plant.
In the late 1980s, university researcher John Dole discovered the grafting method (grafting rarer densely-branched cultivars onto more common sparsely-branched cultivars) – previously known only to the Eckes – and published it. This allowed competitors to flourish, particularly those using low-cost labor in Latin America. The Ecke family's business, now led by Paul Ecke III, decided to stop producing plants in the US, but as of 2008, they still served about 70 percent of the domestic market and 50 percent of the worldwide market.
Diseases
Poinsettias are susceptible to several diseases, mostly fungal, but also bacterial and parasitic. Conditions that promote poinsettia propagation also favor certain diseases. Fungal diseases affecting greenhouse poinsettia operations include Pythium root rot, Rhizoctonia root and stem rot, black root rot, scab, powdery mildew, and Botrytis blight. Bacterial diseases include bacterial soft rot and bacterial canker, while a viral disease is Poinsettia mosaic virus. Infection by poinsettia branch-inducing phytoplasma is actually desirable, as it keeps the plants shorter with more flowers. It is the first known phytoplasma that has economically advantageous effects.
Gallery
<gallery mode="packed">
File:Open wing nectaring of Cethosia cyane Drury, 1770 – Leopard Lacewing (Male) on Euphorbia pulcherrima.jpg|alt=A male leopard lacewing butterfly, which was orange wings with a black outline, landing on top of a poinsettia stalk. Red leaves tilt downwards in a circle around the top, which has yellow flower buds on it|A male leopard lacewing butterfly landing on a poinsettia
File:Euphorbia pulcherrima inflorescence.JPG|alt=An inflorescence of the plant; a bud bulging off from the end of a stem, colored red at the end, with a yellow feature like a pair of lips on the side and a green bulb with a long red top reaching out from inside.|An inflorescence of the plant
File:Euphorbia-pulcherrima-polen.jpg|alt=The pollen of the plant; objects like gray-brown oval seeds, seen under a microscope. A scale line says "200 micrometers"|The pollen of the plant
File:Euphorbia pulcherrima (Barlovento) 01.jpg|A hedge consisting primarily of poinsettias growing along a road in Barlovento, La Palma. |alt=A hedge of poinsettias, about five feet tall, leaning over onto a street. There are few leaves, appearing bare, and many red flowers on long and twisting wood stalks.
File:BocaueChurchjf0105 13.JPG|alt=A dozen poinsettias sit on the ground in front of an altar draped in white. A priest vested in white stands behind the altar.|Poinsettias in a church in the Philippines
File:Poinsettia 01.jpg|Poinsettia in Kolkata, West Bengal, India
</gallery>
See also
- Christmas in Mexico
- Christmas plants