Daisy tree  (Scalesia divisa)

The daisy tree is classified as Critically Endangered (CR) on the IUCN Red List (3).

Owing to their extensive evolutionary radiation in the Galapagos archipelago, the 15 species of daisy tree that comprise the genus Scalesia are often considered the plant equivalent of Darwin’s Finches (4) (5). Indeed, in reference to the Scalesia in ‘The Voyage of the Beagle’, Darwin himself refers to “a remarkable arborescent genus of the Compositae [now known as Asteraceae]” (6). The daisy trees evolved from a single ancestor of the daisy family, that reached the Galapagos Islands many millennia ago (4) (5) (7). Scalesia divisa typically grows as a bush, never exceeding four metres in height (1) (2). Its ovate, divided leaves are arranged oppositely, and its daisy like flower-heads are made up of 30 to 100 white flowers (2).

Scalesia divisa is endemic to the Galapagos Islands, where it is restricted to part of San Cristóbal Island (1) (2) (7).

Scalesia divisa is mainly found on open lava flows including low cliffs (7).

Very little is known about the biology of Scalesia divisa, but, in common with other species in the genus, it has dandelion-like seeds dispersed by the wind (8).

Since humans arrived on the Galapagos, dramatic ecological changes have been caused by agricultural activities, exploitation of native species, and the introduction of non-native animals and plants (7). Consequently, many species of Scalesia are now under significant threat of extinction. For Scalesia divisa, the greatest concern is introduced goats, which have caused extensive damage to the few remaining populations (1) (4).

Scientists at the Charles Darwin Research Station are involved in several projects to restore and preserve populations of Scalesia species, including those on San Cristóbal (4). The management priority on San Cristóbal is to eradicate the feral ungulates that are causing so much damage (7).

Further information on the conservation of the endemic flora and fauna of the Galapagos:

•  The Charles Darwin Foundation:
  www.darwinfoundation.org