The last "rock tree" is being rescued on Robinson Crusoe's island

The seeds of this tree have been collected and sent to the UK Millennium Seed Bank at the Royal Botanic Gardens Kew. There, experts check which ones are able to germinate and try to grow new plants. The botanic gardens use such collections as "insurance" for species that might disappear in the wild.

Important: the species is not yet saved. A few germinated seeds are only a chance. Plants must be grown to maturity, new seeds must be produced and the genetic line must be preserved, or the last wild tree may be the last forever.

Details

Dendroseris neriifolia is a rare island tree in the aster family. In the current Kew Plants of the World Online database, it passes as a synonym of the accepted name Sonchus neriifolius, and its natural range is listed as the Juan Fernandez Islands. The same source categorises the species as Critically Endangered, i.e. "on the verge of extinction", according to IUCN.

The Juan Fernandez Archipelago is located off the coast of Chile. Its most famous island is Robinson Crusoe. Because of its isolation, many endemics - species that are found nowhere else - have developed here. But this uniqueness makes the local nature especially vulnerable: if the island population disappears, there is often nothing to replace it.

According to Botanic Gardens Conservation International, Dendroseris neriifolia grows only in the Juan Fernández Archipelago, and one specimen in a remote ravine survives in the natural environment. BGCI also points out that the plant is among the threatened endemic trees of Chile.

In the new conservation project, experts have collected seeds from the last known wild tree. The original report says 29 seeds were sent to Kew, and X-ray inspection revealed: 25 of them were potentially viable. Some of the seeds were sent for germination, some for long-term storage.

The first results give cautious hope: seven seedlings have begun to develop from the eight seeds sown. Several of the young plants are planned to be transferred to Logan Botanic Garden, which is part of the Royal Botanic Garden Edinburgh system. This is to avoid keeping all the living plants in one place: if one collection dies, there will be a reserve.

Collecting seeds from such a tree is difficult and risky. The last wild specimen grows on a steep slope, so experts work with ropes and nets to reach the branches and not to lose the mature fruit. This is no ordinary "into the woods for seeds" expedition, but a spot rescue operation for a species that has almost no time left.

Why it matters

The story of Dendroseris neriifolia shows how quickly island species can be on the brink of extinction. They often have a small range, few populations, and a narrow ecological niche. When invasive animals, alien plants, fire, or habitat destruction arrive, these species have little or no margin of safety.

A seed bank in this case acts as an emergency archive of life. Seeds can be stored, studied, germinated, and used for future population recovery. Kew describes the Millennium Seed Bank as the largest underground seed bank of wild plants: billions of seeds representing more than 40,000 species and taxa are stored there.

But seed storage is no substitute for wildlife. To truly save a species, we need to understand how to grow seedlings, how to obtain new seeds, how to protect habitat on the island, and whether plants can ever be returned to the safety of their native environment.

Background

The Juan Fernandez Islands are known for having a very high level of endemism. This means that many native plants and animals originated and persisted there. Such islands are often referred to as natural laboratories of evolution: isolation helps species become unusual, but also makes them dependent on very fragile conditions.

These conditions have been strongly influenced by humans and introduced species. Animal grazing, eating young plants, displacement of native species by invasive plants, logging and fires are all dangerous to island flora. In 2024, BGCI reported on the development of an integrated conservation plan for 40 threatened endemic trees in Chile, including species from the Juan Fernandez Archipelago. Invasive flora and fauna, fire, poor grazing management and climate change are among the key threats cited there.

Dendroseris neriifolia has already had conservation attempts outside the wild, but these have proved difficult. In terms of source material, the previous collection at the National Botanical Garden of Chile did not survive the climatic conditions, and some of the plants in the gardens are not suitable for pure seed production due to hybridisation. Therefore, new seeds from the last wild specimen are particularly valuable.

Source

Main source: conservation report on the rescue of Dendroseris neriifolia, a rare tree from Robinson Crusoe Island in the Juan Fernández Archipelago.