Today, we'll start Katherine's series of entries on white-flowered medicinal plants. She writes:
This image of Plumeria obtusa 'Singapore' is courtesy of Dinesh Valke (dinesh_valke@Flickr). For this series on medicinal plants, one should assume that traditional and sometimes scientifically unproven uses are noted, unless otherwise stated. I made my best attempts to find scientific articles where possible.
In Mabberley's Plant-Book, 8 species are noted for Plumeria, with two receiving mention as often-cultivated ornamentals in this tropical American genus: Plumeria obtusa (native to the West Indies) and Plumeria rubra (native from Mexico to Panama). Both of these species are widely cultivated throughout the tropics. Despite having only a couple handfuls of species, hundreds of cultivated varieties have been selected or hybridized, including today's evergreen cultivar. If researching Plumeria rubra, do note that many sites and references use the synonym Plumeria acuminata.
The U.S. National Tropical Botanical Garden (NTBG) provides wonderful descriptions of both Plumeria obtusa and Plumeria rubra, along with their uses. The site notes that Plumeria flowers are used to make lei in Hawai'i, due in part to providing large numbers of showy flowers that retain colour and fragrance. The same source also notes that the scent varies widely among cultivars; this reference by Richard Criley of the Department of Tropical Plant and Soil Sciences at the University of Hawaiʻi at Mānoa details 40 or so cultivars, with comments on fragrance: Plumeria in Hawaiʻi (PDF). The National Tropical Botanical Garden also makes note of the use of Plumeria as an ornamental for cemeteries (hence one of the common names, graveyard flower) and temples (known as temple flower in India and Sri Lanka). Today's cultivar is commonly known as 'Singapore' graveyard flower.
Medicinally, Plumeria species have traditionally been used to treat itches, swellings and fevers, skin eruptions and abscesses, dysentery, herpes, syphilis, coughs and as a purgative. A recent test of the leaves of Plumeria obtusa for anticancer properties did not find significant positive results (unlike some other members of the Apocynaceae): Wong et al. 2011. Antiproliferative and phytochemical analyses of leaf extracts of ten Apocynaceae species. Pharmacognosy Research. 3(2):100-106. However, a 2006 study by Gupta et al. suggested that an extract from the leaves of Plumeria acuminata can soothe inflammation in "both acute and chronic models": Antiinflammatory evaluation of leaves of Plumeria acuminata. BMC Complememnt Altern Med. 6(36).