Trailside plants of the Hawai’i Loa Ridge

While it’s an obvious play off John Hall’s excellent book, my ambitions are much humbler than his. Highlighting native plants on one trail is enough for me. On a whim, I decided to do a short 3-4 hr hike up to the Ko’olau summit via the Hawai’i Loa Ridge trail to check out the native plant life. It’s short relative to my typical all-day hikes anyway.

I would definitely recommend this hike for the average hiker. There are some fairly steep parts of the trail, but it stays pretty broad. At no point does the ridge narrow to a knife-edge. I suppose if you want to hike fast, you can get to the summit in about 1 1/2 hr, but who wants to do that? You’ll miss all the great plants!

The beginning of the trail is dry shrubland that has still many native elements. I don’t know what it is like on the other islands but this area of the southern Ko’olau range is known for ‘Ulei (Osteomeles anthyllidifolia) dominating entire hillsides. Where ‘Ulei is established, even some of the most aggressive invasive plants are scarce.

There are some nice splashes of color as well. ‘Ilima (Sida fallax) and Ko’oko’olau (Bidens sandvicensis) are also very common right along the trail.



There are several stands of non-native ironwood that you have to walk though, but the worst by far is the huge stand of strawberry guava that covers the middle part of the trail. But even in this degraded habitat there are some interesting plants.

In the middle of the guava patch is this lovely native tree: Kalia (Elaeocarpus bifidus). I didn’t see any other individuals, just this one right on the trailside. Kalia is still relatively common, but it is only found on O’ahu and Kaua’i.

This is also another plant that I only noticed in the guava patch. This is ‘Ekaha or bird’s nest fern (Asplenium nidus).

Near the end of the guava stand is a lama (Diospyros sandwicensis) that is carrying a heavy load of parasitic hulumoa (Korthalsella remyana). From here on, the flora is mostly native all the way to the summit. It’s a little different than the shrubland from earlier on the trail as you enter the mesic forest portion. Lots of Koa (Acacia koa) and Ohia Lehua (Metrosideros ssp.) can be found in this part of the trail.

Also in this area are some really photogenic specimens of hala pepe (Pleomele halapepe). Keep an eye out for them.

There is one final change in the vegetation. As you get closer to the summit, you start seeing more members of the wet-forest community.

In this picture is the vine Hoi Kuahiwi (Smilax melastomifolia) growing on Ahakea lau nui (Bobea elatior). There are several other individuals of Smilax that I saw, but they are much closer to the summit.

Here’s a picture that shows some of the differences between 2 of the ferns that are called Uluhe in Hawaiian. Dicranoperis linearis is super abundant throughout the state. It’s distinctive branching pattern makes for fairly easy identification. Diplopterygium pinnatum is the other Uluhe in the picture. It is called Uluhe lau nui because as you can see, the fronds are much, much bigger than D. linearis.

Here is the native holly. Not that terrible invasive Ardisia called Hilo Holly. This is Kawa’u (Ilex anomala). This guy is a shrub growing right by the trailside.

The final plant I wanted to show today is one that only resides in the wet, summit type plant communities of Kaua’i and O’ahu. Lapalapa (Cheriodendron platyphyllum) has super-wide individual leaflets on long petiolules. This combination of traits makes the tree quiver in the slightest breeze. This makes it fairly easy to find this tree from a distance. The name is supposedly an onomatopoeia of the sound of the leaflets as they quake against each other.

So if you have a few hours to kill and want to check out some native plants, the Hawai’i Loa Ridge trail is tough to beat. The ability to see some different native plant communities in a short amount of time makes for a great experience in the wilds behind the dense urban metropolis of Honolulu.

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6 Responses to Trailside plants of the Hawai’i Loa Ridge

  1. XJ says:

    I’ve never hiked Hawaii Loa trail before, just pasted by the terminus on the KST. It will be great doing it now that you’ve given me some things to look for along the way. It’s amazing what you can walk right by while on the trail!

  2. lora says:

    what beautiful plants! i especially like the ko’oko’ulau and the hala pepe. thanks for sharing the great pictures, i hope to see them in person some day.

  3. Glad you guys like them!

  4. XJ says:

    I checked this trail out on Tuesday after reading this. Excellent place to view some really nice plants and this helped make sure I didn’t miss any of them. Thanks again, I really enjoyed reading this and doing the trail. Aloha, XJ

  5. David says:

    Any idea who did the recent trail improvement? The contouring of the mauka side of the final guava hill leading to the area below the summit is very nice.

    • You can thank Aaron’s crew (Na Ala Hele) for that. That last slope was getting awfully sketchy. Although the new section does bypass that neat lama that is loaded with Korthalsella remyana.

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