Grow Aloha: Loulu

Leroy Hanapule “Pule” Krause is a mālama ʻāina technician at Kahanu Garden in Hāna, Maui. Having worked at the garden for 12 years now, he recalls one of the first projects he was involved in—a project that just so happened to involve loulu. 

“For me personally, when I first started working here at the garden, loulu was one of the first big projects that I was able to be a part of, so it’s really special to me,” said Pule. “We built a hale waʻa and we had to gather 3,000 loulu leaves, which was a task of its own. That was one of my first memorable moments with loulu and also here at the garden.”

The dried loulu leaves were used to thatch the hale waʻa, which still stands at Kahanu Garden to this day. Building a Hale Waʻa is no small task, and involves many hands to complete. 

In addition to the hale waʻa, Pule recalls another memorable project involving loulu.

“Having opportunities to go out in the research field when we were able to fly the helicopter up into Waihoʻi Valley—that was definitely another memorable moment. For me, living here in Hāna my whole life, most of us are actually just looking at this valley from the bottom. So now working hands on with the loulu I was able to actually go up in that valley and see this part of east Maui that I never got to see, and be a part of this project with loulu that is pretty critical.”

In partnership with Hawaiʻi’s Plant Extinction Prevention Program and the University of Hawaiʻi’s Lyon Arboretum, Pule and Kahanu Garden Director Mike Opgenorth participated in field surveys focused on finding, identifying, and gathering seeds from one of Hawaiʻi’s rarest loulu palms, Pritchardia woodii. Found exclusively in Maui, this species is critically endangered, known from just two remote valleys on the eastern slope of Haleakalā. Pule reflects on his experience seeing this population of loulu for the first time.

“We went through maps and the team had pinpointed areas where they knew the loulu were. But to be in the helicopter flying into the area and seeing how few loulu there were, and seeing how different the structure of the loulu are—it surprised me. I had thought there was going to be more and maybe bigger clumps, so I was taken back by the lack of loulu up there and how different they are structurally.”

This work is being conducted with generous funding from the International Palm Society. The goal of this project is to help ensure the survival of this special loulu. Looking ahead, Pule hopes that more people will learn about and appreciate loulu—especially the Hāna community, who live in close proximity to one of the rarest loulu species in Hawaiʻi.

“As a community, it’s something that we as Hāna people should be proud of and have a respect for the plant, knowing that it’s ours.”

Makoa Elgin, a master’s student in Botany at the University of Hawaiʻi at Mānoa, shares what he finds most special about loulu.

“From my perspective, being someone who is part of the Hawaiian diaspora community, I think working with native plants and working with loulu in particular is a great way for me to connect with my culture and to learn more about these plants that my ancestors lived with and worked with on a daily basis.”

“I think a huge part of working with loulu is understanding the ethnobotany behind the plant and understanding the cultural uses but also the ecological importance of loulu, being that it is the only palm tree that is native to Hawaiʻi. It’s a very special and unique plant that isn’t found anywhere else.”

Mature loulu are stunning to behold, and can have a large canopy spread—providing shade and protection. Makoa recalls a particularly memorable moment involving a loulu at Lyon Arboretum.

“At Lyon Arboretum, this was the first couple of months that I started interning there, my coworkers and I decided to hike out to the Hawaiian section of the arboretum. There are a bunch of Pritchardia martii planted out there. We thought we’d go out and have lunch out there. It was a beautiful day, perfect for a hike. So we all bring our lunch and we start hiking up to the Hawaiian section, and then as soon as we get up there, it just starts pouring down rain. Absolutely pouring. Lyon Arboretum is in the back of Mānoa Valley so it can rain unexpectedly. So we just ran under a loulu and we all had our lunch covered by the loulu fronds and it was truly a form of protection like an umbrella. That was a special moment, just remembering how the loulu protected us from the rain and kept us perfectly dry.”

Makoa shares more about his master’s thesis, which is centered on loulu.

“My project is basically looking into the hybridization of loulu species and also looking at their breeding systems and their pollination biology. We’re hoping to better understand how the flowers develop—from when theyʻre in bud to when they open, until when they set fruit.”

“Part of my project revolves around hand pollination and forming a hand pollination protocol that can be used to maximize genetic diversity—so basically being able to take pollen from one individual and put it on the flower of another individual that you know are distantly related so you can maximize that genetic diversity and there’s not too much inbreeding.”

“Regarding hybridization, it’s a big deal for garden collections because there are so many different loulu species out planted next to each other. If we’re collecting fruits for conservation purposes, whether it’s for seed storage or to grow in a nursery to eventually out plant in the wild, you want to be sure you know the identity of the fruit and seed that you’re collecting. So if you have several species all planted next to each other and they all flower at the same time, no one has done a formal hand pollination test to see if, for example, species A and species B can hybridize. Then we know that we need to be careful when we collect seeds of Pritchardia minor for example if it’s outplaated next to a different species of loulu.”

Given the threat of CRB in Hawaiʻi, Makoa’s work is especially timely.

“CRB was kind of the pushing force for this project to start. On Oʻahu, CRB has been present since 2013, so it’s been known as an issue but it’s starting to get worse. With CRB spreading to Kauaʻi, Maui, and Hawaiʻi Island, it’s a pressing issue. Our goal is to understand as much as we can about loulu.”

At Limahuli Garden and Preserve, Dr. Uma Nagendra, Conservation Operations Manager, speaks more about the critical role loulu play in Limahuli valley and across Hawaiʻi.

“Loulu are one of the many endemic species that are critical to multiple ecosystems throughout Limahuli Valley. There are at least two species of loulu that are present in Limahuli Valley that are found no where else in the world except here on Kauaʻi—Pritchardia napaliensis and another species that we are actually still working to identify. The taxonomy is a little unclear at this point.”

“Loulu used to be one of the foundational species throughout Kauaʻi ecosystems, but since the introduction of invasive rodents and continued habitat loss, they have been declining and now many of them are endangered species.”

Dr. Nagendra shares more about the work happening at Limahuli aimed at supporting loulu populations.

“Some of our roles in Limahuli and across a lot of conservation organizations is to protect those wild species. Also at Limahuli, we out plant them in our living collections in the garden as well as in our restoration areas in the preserve to maintain these populations so that they continue to thrive.”

“One of the ways that we do that is by protecting them from rodent damage. The rodents will eat the seeds and when they do that, then you no longer have baby plants that can grow up into adults. So we use trapping grids—automatic resetting traps—throughout areas where thereʻs wild populations. We have actually seen greater success of ripe fruit that we can collect from those trees. We’ve had these rodent trapping grids going for over 10 years now. It used to be that you would have to collect fruit while they were still unripe and ripen them in a paper bag so that you could actually propagate them. But now we’ve had enough success with the rodent control and management that we can actually get ripe fruit on the tree itself and collect it and sow it immediately instead of having to wait for it to ripen in a paper bag back at the office.”

These results offer hope for the future of loulu in Limahuli. But without these predator control efforts, what would happen to loulu? 

“A future without loulu, that is one where we’re losing a foundation species for entire ecosystems. I always think of the first time I saw them in the Upper Preserve. The way that they stand even above the canopy, to me they look like sentinels of the forest. To me they look like they’re keeping watch over everything else. To imagine that beauty and those spirits would be gone, it’s not pleasant to think about.”

So is there anything we can do to help ensure a future for this special tree?

“One of the biggest things that everybody can do is be super cautious about how we’re moving mulch and plant material around. We’ve learned that’s one of the most prevalent ways that CRB travels and spreads across islands. As much as possible, try to keep mulch and plant material sourced very locally. This is something we can all take part in.”

In addition to green waste management, we can all help the Hawaiʻi Invasive Species Council, also known by the acronym ISC—to keep an eye out for CRB and CRB damage.

“Keep on the look out for beetles, larvae, and other things that may be suspicious. The ISC groups are working really hard but they can’t have eyes everywhere. It’s up to us to help out with that process if we can.”

“The second thing is, if you have the opportunity to plant more, plant more! Even a tiny native forest in your yard increases habitat for these plants.”

“I think it’s super important to plant native plants in your yard,” added Makoa. “We have enough invasive plants here in Hawaiʻi. The more native plants you can put in your yard, the better. Personally at my house on Oʻahu we have two little baby loulu planted in the front yard, and they’re just gorgeous. I think it’s very special to be able to have one of these palm trees in your home.”

Interviews were edited for clarity and length. Artwork by Carly Lake.