Euphorbia deppeana

Euphorbia deppeana is a rare species of flowering plant in the family Euphorbiaceae[2] known by the common names Deppe's broomspurge and Oahu sandmat. It is endemic to Oʻahu, Hawaii, where it is known from only one population[3] in moist shrublands on Nuʻuanu Pali.[4] Like other native Hawaiian euphorbs it is called ʻakoko locally.

Euphorbia deppeana
Conservation status
Critically Endangered  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Malpighiales
Family:	Euphorbiaceae
Genus:	Euphorbia
Species:	E. deppeana
Binomial name
Euphorbia deppeana Boiss.
Synonyms[2]
Anisophyllum californicum Klotzsch & Garcke Chamaesyce deppeana (Boiss.) Millsp. Chamaesyce festiva (Sherff) Croizat & O.Deg. Euphorbia festiva Sherff Euphorbia pauciflora Nutt. ex Seem.

This shrub is erect or sprawling in form. The stems may exceed a meter in length and contain milky sap.[4]

The plant has never been abundant as long as the area has been surveyed for flora.[3] It was not seen for many decades and by the 1980s it was feared extinct.[3] The single known population was rediscovered in 1986 and it contained fewer than 100 plants.[3] In 1994 it was added to the United States' endangered species list.[3] By 2007 the population was estimated to have exceeded 100 plants, but they are hard to count because they grow on a sheer rock cliff in the middle of a tourist area.[3]

The species is still considered endangered because there is only a single population and it is threatened by a number of processes.[3] Several invasive plant species have moved into the area and compete with the rare native for water, light, nutrients, and physical space.[3] The most important non-native plants in the area include ironwood (Casuarina equisetifolia), Hilo grass (Paspalum conjugatum), Christmasberry (Schinus terebinthifolius), and the common guava (Psidium guajava).[1][3] Other threats to the species include fires and human interference with the plants.[1][4]