Mt. Ka’ala: A walk to remember

Trematolobelia kaalae

“Whiskey Tango Foxtrot Sebastian? You’re comparing a hike into some of the most intact native forest on O’ahu to a sappy Nicholas Sparks book?! There are relictual native species in the area that the general public rarely gets to see and this is how we get to hear about them… wait, don’t tell me you cried?” Well…yes, yes I did…

So I took the hike as part the the field trip for UH Botany 661. Now technically, it is supposed be that you learn about the plants, id them in the lab and remember what you learned to help you identify them in the field. Identifying native plants is mental anyway, not my fault that a most apt description for this field trip is associated with some tragic teenage love story.

Regardless of Mandy Moore, it had been awhile since I had been to the highest point on O’ahu. I’d really like to see how much had changed or stayed the same since I was last there. This part of the Wai’anae volcano is not in the Ko’olau rain shadow, it gets much more rainfall and is often socked in by clouds. On this hike alone, we would see how native plants have adapted to just about the entirety of moisture regimes available on O’ahu.


The lower, drier beginning of the hike was highly degraded. Years of ungulate pressure has taken its toll of the flora in the valley. Agroforestry changed the composition of the forest too; we passed by many large macadamia nut trees. Even amongst the exotics, we were coming across various native plants. Surprisingly some of the first we saw were mamaki seedlings (Pipturus albidus). The mamaki were doing well in drier habitat than I normally see them in.


Further up the valley, we were getting into a more mixed native and invasive forest. A lot of strawberry guava was around, but there was quite a number of large koa (Acacia heterophylla) and ‘ohia lehua (Metrosideros polymorpha). Another dominant plant in this part of the forest was ‘a’ali’i (Dodonea sp.) There were also a lot of interesting native understorey plants like this ‘akoko (Euphorbia multiformis).


We also saw a healthy population of dry forest ‘akia (Wikstroemia sp.) as well. Neither the ‘akoko or ‘akia are particularly endangered. In fact, certain strand types would not be out of place with surfboards and beach bbq’s. But I always like to bring up understorey plants whenever I blog about a hike. Far too many areas have native canopies but highly invaded understories. It was great to see some native plants had survived mammalian herbivory closer to the ground.


Less browsing pressure of small understorey plants also allowed seedlings of larger plants to thrive too. Here, we came across a sapling of ‘ala’a (Planchonella sandwicensis).


Once we reached the ridgeline heading toward Ka’ala, we notice the composition of the forest change a little bit more. There was still a lot of ‘ohia, but we were also noticing much more Pilo (Coproma sp.) In fact, the area reminded me a lot of Palikea.

While the ridge was dominated by native plants it was the summit that really brought a tear to the eye.

kaala summit

The native forest almost envelopes you! Just like unrequited love… well perhaps not. While not completely intact per se, the summit area of Ka’ala has some of the healthiest native forest on O’ahu. Here, we can make out a couple things. The dominant trees in the wet forest are ‘ohia (small dark green leaves on the upper left) and ‘alani ((Melicope sp.) shiny leaves on the right). Another thing you can sort of make out is the scale. I don’t know if it is because of the wind, wet substrate, or other factor but a large majority of the trees are only between 10-15 ft tall. It makes for easier identification when you don’t have to strain your neck to try and key out some leaves 40 feet above you.



One thing I forgot (or, to keep with the theme, not remembered) was all the pukiawe (Leptecophylla tameiameiae) at the summit. I’m used to seeing pukiawe in dry shrublands early on trails, so it was a little jarring to see it in the wet forest.

Trematolobelia kaalae close

Somebody is going have great shots in the next few weeks. A lot of the koli’i (Trematolobelia kaalae) were nearing full infloresence. Unlike the other Trematolobelia spp, T. kaalae is the only extant koli’i that flowers in the spring. (Lammers, 2009) Unless someone has seen the extinct T. rockii. I’ll keep trolling social media and hope to see a spring blooming koli’i on Moloka’i! The rest of the genus typically flowers in the late summer or fall.

Astelia menziesiana

Another neat plant that we came across that isn’t usually seen is this pa’inu (Astelia menziesiana). I’ve only seen Astelia spp. in 2 other, but similar, locations: Pihea trail on Kaua’i and Konahuanui in the Ko’olaus. All three are wet forest, summit areas.


In a lot of these teenage love stories, there is some sort of secret revelation that threatens the nascent romance. He is secretly a poor kid from the other side of the tracks, she has already signed up for a 3 year internship across the country. Well, here is the secret that threatens our story. There is nothing more closely associated with tropical paradise than pretty orchid flowers. There are dozens of showy, gorgeous orchid species that we grow throughout the state. Heck, one of the most common nicknames for Hawai’i island is the orchid isle.

*cue somber tear-jerking music* “Babe, I don’t know how to tell you this, I know how you love orchids so much. But… none of the orchids you know are native. There are only 3 native species of orchids and they all have non-descript flowers. You’ll still go to prom with me won’t you?”

This tiny plant that looks like a weed is one of our native orchids. Just a couple leaves on a short stem, that’s it. This is honohono (Anoectochilus sandvicensis). The leaves do resemble that weedy bane of lo’i and streams thoughout the state Commelina difusa. Perhaps that is how the name got transferred. Regardless, this can be a surprised to some people. Most popular orchids aren’t from here?! Or to quote every spurned protagonist in these types of movies: “I don’t even know you anymore!” (*Edit not orchid. Can’t fall in love with the prose!)

Gunnera petaloidea

Let’s move to the denouement before things get too sappy (*Edit or more incorrect 🙂 ). These are the striking leaves of ‘ape’ape (Gunnera petaloidea). I remember seeing ‘ape’ape the first time I went up to Ka’ala. If you are still not impressed, let me put my hand in for scale…

Gunner petaloidea scale

These are impressively large leaves! Notice too that it’s in flower.

Gunner petaloidea flowers

These plants are only found in the wet summits of the Hawaiian archipelago. On O’ahu, they are really only known from this part of the Wai’anaes. Bottom line, there aren’t very many places that you will stumble across this plant. We felt lucky to see it. All these plants help make Mt. Ka’ala such a special place to visit.

So when did I cry? The next day, actually. 8 hours of climbing will do a number on your major muscle groups! But it was definitely worth it. Too see a healthy native ecosystem full of plants that aren’t normally seen in your everyday life? That’s worth a Saturday matinee. At the very lest a rental on netflix. Join me next time for the sequel!


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