Tag: Endemic

‘Ohi’a lehua (Metrosideros polymorpha)

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Search for native Hawaii plants to look for, and undoubtedly the name of ‘Ohi’a lehua will show up on the list. This charismatic plant is the most common native tree found in Hawaii. It is an evergreen, highly variable tree found on the six major islands. Its flowers are showy and come in various colors ranging from yellow to red, red being the most common variation. Flowers are produced as inflorescence made up of a mass of long stamens. Ohia lehua forests are essential habitats for various native birds as it is one of the few Hawaiian plants capable of producing nectar. They host both native and introduced birds. To the right is a ʻApapane (top) and a Japanese white-eye bird move around a vast ‘Ohi’a tree.

The Ohia lehua is a crucial early colonizing species that grows straight out of basalt. It is among the first trees that are growing on recent lava flows. It is even tolerant of extreme sulfur content found along sulfur banks on the big island. A sign along the trail mentions the severe conditions on the banks and the possibility of the ‘Ohi’a colony evolving into a distinct subspecies over generations.

Its tolerance to various growing media leads to extreme tree size variations. In favorable soil, in rainforests, it can grow to be more than 80 feet tall, while when growing in boggy ground or on freshly cooled igneous rocks, it grows as a small prostrate shrub. In wetter conditions, Ohia branches drop down aerial roots that stay suspended and absorb moisture from the air. Shown here is an enormous specimen of Ohia lehua.

Current preservation efforts for the ‘Ohi’a have faced various issues, including the curse of introduced species like ornamental/livestock feed grasses that quickly take over ‘Ohi’a forests, climate change, and the latest fungal pandemic afflicting these plants, the rapid ‘Ohi’a death. First reported in the big island of Hawaii, mitigations efforts have been taken to help stop the spread of the fungus, including closing down of forests to visitors. Humans can carry these pathogens on their shoes as they walk through the forest floor. To avoid spreading the disease, visitors should use the shoe cleaners placed along trails. Please be mindful of your presence as an outsider when you visit these unique habitats.

‘Ama’uma’u fern (Sadleria cyatheoides)

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Five Amaumau fern grow on lava flows created in the early 20th century with other pioneer species like ‘Ohi’a lehua.

Driving through the big island of Hawaii on the saddle road, the scenery changes drastically from vegetation introduced by ranches to hard lava rocks with little to no soil. Growing on it are some of the most versatile and hardy species of plants. These pioneer species are the first to inhabit rocky lava beds after the erupted magma cools down. Among those species is the Amaumau fern. The first time I saw this fern, I assumed it belonged to the more common fern order of tree ferns. I was pleasantly surprised to learn more about this fantastic fern. For now, it has taken the spot of my favorite species of ferns!

Amaumau fern belongs to the endemic genus Sadleria. It is found in all major islands of Hawaii and grows on lava flows, open spaces, and wet forests. The fern can tolerate extreme heat and direct sunlight, which gives its leaves a red tinge. The plant can grow vertically, like a small tree fern, or horizontally with its rhizomes covered with silver-colored dead leaves. 

The crater Halemaʻumaʻu, home to the goddess of fire and volcanoes, Pele, derives its name from this fern. Halemaʻumaʻu means “house of the ʻāmaʻu fern.”

A brief Hawaiian detour, Hawaiian Silversword (‘ahinahina)

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Winter months in New Jersey can get hard, with limited sunlight and all the beautiful flora hibernating for the winter. I am lucky enough to have a sister who lives in Hawaii! While in Hawaii, I couldn’t help but botanize the local native flora. On the island of Oahu, it is sad to see that most of the landscape is covered with invasive plants and birds from across the world. The island’s native forests are at risk of being wiped out thanks to escaped plants from people’s gardens. Even so, one can find the surviving remnants of a once-thriving ecosystem and efforts made to preserve it. For the next few weeks, I will try to unload my photographs from the big island of Hawaii and the island of Oahu.

First off is possibly the most famous native plant in the botanical world, the Hawaiian silverswords! Silverswords are massive showy plants that grow on the sides of volcanoes on two of Hawaii’s islands, Maui and Hawaii. The plants are large silvery rosettes forming hardy plants that can survive climate extremities. Once common across the landscape, these large, showy plants suffered dramatic decline due to cattle farms and visitors ripping them out to keep as souvenirs. These plants are now federally protected, and restoration efforts are underway to try and save the various subspecies of the plant.

Three silverswords just done flowering and a large plant that should flower in the next few years!
A young plant, far from maturity
Some silverswords growing in clumps.
A rosette opening up.

As is true for most island species, the two islands inhabited by the silverswords have produced two closely related subspecies. The Haleakala silversword grows around the volcano Haleakala in Maui. The Mauna Kea silversword is found around the peak of Mauna Kea on the big island. Efforts to save the Haleakala silversword have resulted in a resurgence of the plant under management, but the Mauna Kea has yet to see the same fate. Less than 50 of these plants continue to grow naturally in an inaccessible part of the Mauna Kea, saved from the cattle that have decimated its population. 750+ now grow under protection, many fenced off from livestock.

I was lucky enough to find these plants in a protected trail in Mauna Kea, kept under watch but left to the elements. Seeing them was a delight. At 9000 ft, the climate is not what you would expect from a place advertised relentlessly as a tropical paradise. The weather is much colder and harsher at that altitude, allowing the unique plants to survive. I visited them after they had done flowering for the year. Still, their giant flower stalks were left looking impressive, with a fresh batch of seeds! Hopefully, I can revisit them in the coming years and witness their magnificent blooms.

Silverswords are further empiriled thanks to climate change. They grow in a narrow band of altitude and depend on their delicate ecosystem for survival, with climate change, the habitable altitudes could change, further narrowing its natural range.