Bryant is the author of today's entry. He writes:
Thank you to Anne Elliott (aka annkelliott@Flickr) for today's image of Euphorbia punicea. Another image of this species was submitted by frequent BPotD contributor 3Point141: Euphorbia punicea, also shared via the Botany Photo of the Day Flickr Pool.
Jamaican poinsettia is an evergreen succulent shrub that is native to Jamaica, but has been introduced to other parts of the Caribbean and southeastern United States (mainly Florida). Euphorbia includes an exceptional diversity of species, ranging from cactus-like succulents to the widely cultivated Euphorbia pulcherrima (poinsettia) that is often used for decoration during the December holidays in some parts of the world. To see some examples of the diversity within Euphorbia and the Euphorbiaceae, check out the site of the International Euphorbia Society. Even solely within Euphorbia punicea there is observed to be much morphological variation, see: Rikus van Velduisen. 2006. Some Notes on Euphorbia punicea Swartz and Related Species (PDF). Euphorbia World. 1(3):5-8?.
Euphorbia punicea begins to flower near mid/late December and may continue to do so until around July; the development of flowers is thought to be triggered by slightly shorter days. This species typically grows to 3-5m high (although a few much taller specimens have been described), and is commonly found on rocky limestone soils in its native habitat. The pink structures are bracts, and their bright colouration is triggered by the process of flower initiation. A combination of anthocyanins and flavonols pigment the bracts. Bract colour (from red to pink) in related Euphorbia species has been observed to vary in part with the proportion of anthocyanins to flavonols, see: Stewart, RN et al. 1980. The anthocyanin and flavonol composition of three families of poinsettia colour sports. Journal of Heredity 71:140-142.