The giant daisy tree Scalesia cordata is one of 15 species of the endemic Galapagos genus Scalesia. It is restricted to the humid zone of the Sierra Negra and Cerro Azul volcanos on southern Isabela, where it used to form a dense forest, home to endemic Darwin's finches and flycatchers. This forest covered an area of c. 17,300 ha in the 1900s but today only c. 0.1% of the original distribution remains, mainly as a result of land-use change, fires and, recently, invasive plant species, especially guava Psidium guajava, blackberry Rubus niveus and Siam weed Chromolaena odorata. These invasive plants form a thick and dark understorey that prevents germination of the small and light-dependent S. cordata seeds. This interruption of natural regeneration has caused a marked decline of S. cordata. Of 1,075 trees recorded in 2002 only 17 remained in 2019, and the Charles Darwin Foundation and the Galapagos National Park Directorate estimated then that there were only c. 300 individual trees left in the wild. Scalesia cordata has been categorized as Endangered on the IUCN Red List since 1998 but the assessment is outdated. The 2019 data indicates that S. cordata should be categorized as Critically Endangered.

In 2021, with funding from the Keidanren Nature Conservation Fund (Japan) and Fondation Franklinia (Switzerland), we embarked on a mission to save the giant daisy tree from extinction. From drone imagery of > 500 ha and several field trips, we have so far identified and mapped 980 S. cordata trees and the invasive plants threatening them. Control of invasive plants is being carried out, and this has facilitated the natural regeneration of a total of c. 150 S. cordata seedlings at some of the study sites. We have also managed to propagate c. 800 S. cordata seedlings in the Galapagos National Park Directorate greenhouse, and these have been planted at several study sites. Two years of intense conservation efforts resulted in the recording of a total of almost 2,000 S. cordata trees on southern Isabela in October 2023.

However, the survival of S. cordata is not yet secure. It has a low number of fertile seeds when self-pollinated, despite being a short-lived tree (10–15 years). We therefore have to continue restoration efforts until self-sustaining S. cordata populations are established.

Research was carried out under permits PC-18-21, PC-28-22 and PC-15-23 issued by the Galapagos National Park Directorate. This publication is contribution number 2603 of the Charles Darwin Foundation for the Galapagos Islands.