Thought to be extinct in the wild, native plant found on Big Island

Oct. 13—Early naturalists once described it as being plentiful on Hawaii island and even dominating under the shade of koa trees and on the bottoms and slopes of old volcanic craters.

Early naturalists once described it as being plentiful on Hawaii island and even dominating under the shade of koa trees and on the bottoms and slopes of old volcanic craters.

But with grazing and habitat destruction, only a few Delissea argutidentata plants were known to exist by the early 1970s and the last one in the wild disappeared 20 years ago.

That was the thinking until last year, when a small population of the species was rediscovered in the same area it was known to exist in the early 1970s.

Now, Kamehameha Schools, the state Department of Land and Natural Resources and Three Mountain Alliance said they have successfully planted 30 keiki plants propagated by the Volcano Rare Plant Facility from seeds retrieved from the small population of the newly rediscovered plant.

The plant was rediscovered in early March 2021 in a crater on Kamehameha Schools land in a remote section of mauka Kona on Hawaii island. Officials aren't describing the exact location to protect the plant.

Three Mountain Alliance field technician Kallie Barnes found the plant while collecting seeds from other plants for use in nearby restoration areas. Three Delissea plants were growing on a dead mamane stump near an old enclosure, where the remains of a larger plant were visible.

"It's pretty amazing we found it here, " said Amber Namaka Whitehead, Kamehameha senior natural resources manager.

Delissea argutidentata looks somewhat like a palm tree, with a long trunk and no branches, topped by a round cluster of leaves. It can grow up to 35 feet tall.

"No other member of the lobelia family looks quite like this, " Whitehead said.

Delissea argutidentata was last seen in the area in the early 1970s within three small enclosures created by a former tenant. Whitehead said it is fortunate the enclosures were built because it's possible the plant may have never been seen again.

A plant pressing collected from the area in 1971 notes that only three plants were remaining, but the tops of the plants were damaged, probably by cattle, and thick grass likely made it extremely difficult for them to come back to life.

In 1992 a single individual plant was rediscovered at Puu Waawaa but it died in 2002, officials said. The good news is that seed had been collected from the plant and many of its outplanted keiki still survive.

"The fact that it was discovered here, brings it back to this place, " Joshua VanDeMark, DLNR Plant Extinction Prevention Program coordinator said in a news release. "The reintroduction of a rare species like this is so critical because the habitat is what will allow it to persist into the future."

Of the 16 recognized species of Delissea, 14 are extinct and the remaining two are endangered.

There is no known Hawaiian name for Delissea argutidentata, officials said, but they are quite similar to plants in the related genus Cyanea and could have been known by the same name, haha. Given its tall form, one could descriptively call the plant haha ki ʻeki ʻe (tall haha ).

Over the past year, staff from all three organizations have taken actions to protect the small population of plants and to safekeep its genetics.

Staff from all three organizations visited the area following the discovery and installed a temporary fence around the plants. They also collected eight ripe fruits, some of which were sent to Lyon Arboretum in Honolulu for storage and others taken to the Volcano Rare Plant Facility for propagation.

In February 2022, Kamehameha Schools staff revisited the population and collected 12 fruits from the two largest plants. These fruit samples were also sent to Lyon Arboretum for storage. The team also observed two tiny wild Delissea argutidentata seedlings within the new enclosure.

Whitehead said Kamehameha has been a good steward of the land but it has historically focused on the entire landscape. She said Kamehameha will devote more energy to rare species.

"Both are important, " she said. "We need to have a healthy native ecosystem, but every single species is important to our cultural identity and the health and well-being of our people."