Pōkalakala (Polyscias racemosa; formerly Munroidendron racemosum) – Botanical racism?


    Almost immediately upon their arrival to the Islands, American and European missionaries started to persuade and later force Hawaiians to abandon their religion, their culture, and even their language. According to them, nearly everything Hawaiian was bad. Unfortunately, this racism also permeated through the botanical community at the time. While early explorers to Hawai‘i described the Islands as a botanical paradise, prominent botanists in Hawai'i during the 1800s and first half of the 1900s often described native Hawaiian plants as "weak" and "inferior" to plants from other tropical lands. This botanical racism was most evident during the early 1900s when botanists and Territory officials all agreed that alien rather than native trees should be used to reforest the slopes and mountains denuded by cattle during the 1800s.

    Beginning in the 1970s, a reawakening pride by Hawaiians in their culture led to a renewed interest in everything Hawaiian, including the native flora. By the 1990s, State laws and regulations had been changed to permit the cultivation of Hawai‘i's endangered plants and encourage the use of native plants in urban landscaping. I remember this as a hopeful time, a time when John and I thought our book was needed and welcome. 

    Today, I am less optimistic. State officials now seem more interested in regulating rather than encouraging the planting of endangered plants by anyone other than professional conservationists. And, is there anywhere in Kapolei or Kailua-Kona where you are not surrounded by alien shower trees rather than native Hawaiian plants? Similarly, the overwhelming majority of plants for sale at local garden shops and home improvement stores are — admittedly pretty — alien weeds. Which brings me round to pōkalakala, an endangered tree, endemic to Kaua‘i, that is easy to propagate, relatively easy to grow and maintain, and is undeniably beautiful. Yet, I almost never see it in residential yards or commercial landscapes. Why? Are we still suffering from botanical racism?

Habitat & Appearance: A small extremely rare endangered tree, endemic to Kaua‘i, where it grows on coastal mesic cliffs and in lowland mesic forests. Pōkalakala has smooth gray bark, soft wood, and thick semi-flexible branches. The undersurface of its large pinnate leaves are covered with a dense fuzz while the upper surface is glabrous; young leaves are fuzzy top and bottom. During the summer, pōkalakala may lose some to all of its leaves. Small pale yellow flowers with red centers hang in a long rope-like inflorescence sometimes as much as two feet long. These mature into soft downy drupes with a dark purple pulp, each containing several flat seeds.

(Top to Bottom) Wait until these nearly-ripe fruits are soft and purple before collecting them (photograph courtesy of David Eickhoff ©). Seedling. Young tree at Maui Nui Botanical Gardens (photograph courtesy of Forest & Kim Starr ©). (Header photograph courtesy of u/Beardor on r/BotanicalPorn; reddit ©.)

Pōkalakala in Hawaiian Culture: There are no recorded ancient uses of pōkalakala. However, modern cultural practitioners have discovered the fruits produce a dark purple dye when wet, drying to a lighter plum color.

Collecting Seeds: I have never seen a wild pōkalakala. In cultivation, pōkalakala has a wide flowering and fruiting period all the way from July to February, with (in my experience) the fall months being the most common time to find ripe fruits. Collect the fruits when they are soft and the inner pulp is dark purple. Separate and clean the flat seeds either by hand individually or collectively with a colander. Test the seeds for viability in a cup of water; the viable seeds will sink. I have almost always sown pōkalakala seeds within a few weeks of collecting the fruits. The few times I have sown seeds stored in a refrigerator for more than six months have always resulted in little to no germination.  

Growing from Seed: Sow your pōkalakala seeds immediately after separating and cleaning them using Method One. The first seedlings should appear in a little over a month. Seedlings start out with a single simple (i.e., non-compound) true leaf. As they grow, they begin producing compound leaves with three, then five, and eventually seven-plus leaflets. Transfer each seedling to its own pot after it puts out 1-2 true leaves. 

    Seedlings grow best under shade (i.e., 50% - 70%) in the nursery, and should be 12-18 inches tall in 6-12 months. Aphids and mites that disfigure the new leaves are the two most common pests to infest seedlings and young plants. Refer to Enemies in the Garden for methods of combating these foes.

Growing from Cuttings: I have never tried to grow pōkalakala from cuttings, and do not know of anyone who was successful.

Growth in the Garden: Plant out your pōkalakala when it is a foot or more tall in a site with partial shade for the quickest growth. The growth difference between a shaded and full-sun site can be dramatic. For example, at Leeward Community College, we planted two equal age pōkalakala (from the same seed batch) within several feet of each other, one in the shade of a nearby monkeypod tree, and the other in full sun. Both received the same amount of water from the automated sprinklers. After three years, the full-sun tree is now a healthy eight-foot tall tree. In contrast, the shaded tree is today twice as tall (i.e., 16 feet), has three main side branches, and has started flowering; the full-sun tree has no main side branches and no flowers. 

    Remember that pōkalakala naturally grows in mesic areas on Kaua‘i and cannot survive a drought; this is in contrast to its sister species ‘ohe makai (Polyscias sandwicensis) which grows in dry forest and shrubland. Knowing when and how much to water your tree can be tricky because often pōkalakala will drop most of its leaves just prior to the start of its blooming season making you think it is water-stressed. Ultimately, how much you need to water your pōkalakala will depend on the amount and seasonality of rain in your garden. My best advice is to monitor the soil moisture surrounding your tree and never let it become bone dry.

Diseases & Pests: Young pōkalakala are frequently attacked by sap-sucking arthropods such as aphids, mealybugs, white flies, and mites that usually focus their attention on the youngest leaves. Older plants seem to better ward off these infestations. Often, a few sprayings of horticultural oil will eliminate these pests. Similar to ohe makai, the trunk at the soil-air interface seems to be the most vulnerable spot for both young and mature pōkalakala. Inspect this area frequently for damage caused by microbial rot or chewing pests (e.g., cockroaches, mice), and intervene before it is too late. Also take care when weeding not to wound this area. While I have not encountered these pests, Kerin E. Lilleeng-Rosenberger (2005) has seen ants and spotted leafhoppers on pōkalakala. And, David Eickhoff warns us that a "type of boring insect is very destructive and can destroy a mature tree in a short time if not given immediate attention. Look for sawdust type material coming from tiny holes. This pest works fast, so treat as soon as it is noticed." David recommends treating the tree with a systemic pesticide like imidacloprid along with a fungicide.

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