Artemisia australis
Asteraceae or Sunflower family [Nature Clearly]
Synonyms: Artemisia australis var. eschscholtziana, Artemisia australis f. menziesioides, Artemisia australis var. microcephala, Artemisia australis f. pauciflora, Artemisia australis f. skottsbergii, Artemisia eschscholtziana, Artemisia hillebrandii, Artemisia microcephala
ʻĀhinahina
Hinahina, Hinahina kuahiwi
Oʻahu wormwood
Natural Range & Environment
Artemisia australis is endemic to all the main Hawaiian Islands, where it grows on exposed cliff faces from near sea level to 1,065 m (3,494 ft) [Wagner et al. 1990]. During my (Koebele) decades of hiking in Hawai‘i, I have yet to see a wild A. australis growing anywhere other than a rocky cliff face. Similarly, except for cultivated plants and restoration plantings (e.g., on Kaho‘olawe), all the online photographs I've come across of A. australis were of plants growing on or at the base of rocky cliffs.
ʻĀhinahina produces clusters of tiny yellow flower heads (photograph courtesy of Gerry Carr CC BY-NC 4.0). The gray or silvery color of ʻāhinahina's deeply divided leaves is the result of very tiny hairs that reflect away sunlight and heat. On O‘ahu, a slightly greener wild ʻāhinahina in its typical habitat — a rocky cliff face (photograph courtesy of Andrew Evens CC BY-NC 4.0). On Maui, a cluster of small cultivated ʻāhinahina in a residential landscape (photograph courtesy of Forest & Kim Starr CC BY 3.0 US). Also on Maui, a larger cultivated ʻāhinahina surrounded by other native Hawaiian plantings (photograph courtesy of Forest & Kim Starr CC BY 3.0). Generally, ʻāhinahina on O‘ahu are greener than those on Maui.
Description
Artemisia australis is a small to medium-sized shrub (see photographs above) with a lifespan greater than five years that can vary considerably in leaf shape and color. While all ʻāhinahina have finely divided leaves, some forms, such as those found on Ni‘ihau, Moloka‘i, and Lāna‘i, have leaves divided into broader segments than ʻāhinahina growing on the other Islands [Wagner et al. 1990]. The amount of leaf pubescence (hairiness) can also vary with location for wild plants and with environmental conditions for cultivated plants (e.g., less light or more water tends to yield less pubescent plants). From our field observations, ʻāhinahina on O‘ahu tend to be less pubescent and, therefore, greener than plants on Kaua‘i or Maui; we're unable to comment on the pubescence of ʻāhinahina from the other Islands.
ʻĀhinahina leaves are faintly to strongly aromatic, particularly when crushed or rubbed, and have a sage- or anise-like (or, for locals, lychee-like) fragrance. And, while never brave enough to taste the leaves, I (Koebele) have been told and read that they are quite bitter.
ʻĀhinahina has small yellow turning to brown, daisy-like flower heads (i.e., compound flowers) with outer female and inner perfect (bisexual) florets [Wagner et al. 1990] that develop on branched spikes (panicles) that extend above its foliage. Each pollinated floret develops into a small pale brown cypsela (a type of dry single-seeded fruit) [Seeds of Hawaii].
Artemisia australis can hybridize with other Artemisia species, both native (e.g., A. mauiensis [Wagner et al. 1990; Plants of Hawai‘i]) and possibly non-native in Hawai‘i; the naturalized mugwort (A. vulgaris) has been successfully crossed with other Artemisia species [James et al. 2000] and even with a chrysanthemum [Deng et al. 2010]. Therefore, if you intend to collect and sprout seeds from your ʻāhinahina, first look around your neighborhood for other Artemisia species and chrysanthemums, and then consider bagging and hand-pollinating your plant to be certain the seeds are genetically pure. A. australis cuttings root relatively easily, making it the safest way to generate new plants.
Growth Requirements
General
Artemisia australis requires little care and is a striking addition to any landscape. Use it as an accent or, spaced about three feet (1 m) apart, as a hedge. ʻĀhinahina is an excellent replacement for the popular and non-native Dusty Miller (Jacobaea maritima; syn. Senecio cineraria). ʻĀhinahina can also be kept in a container; gradually increase the pot size as your plant grows until it is the size you want.
Wild ʻāhinahina are nearly always seen growing directly out of cracked rocks (i.e., cliff faces). Let this be your guide for soil or media selection. In the ground, if your soil is mostly clay and/or drains water poorly, consider creating a mound of cinder or lava rock and planting your ʻāhinahina on top. If you intend to keep your ʻāhinahina in a container, fill the container with black cinder and a bit of sphagnum peat moss (i.e., 50% or more cinder).
Water your new ʻāhinahina about once a week until it is established in the ground (i.e., for one to two months) and is putting out new growth. Then, cut back on your watering, providing just enough water to prevent wilting of the plant's leaves. (Note that plants with severely wilted leaves may not recover.) The surface soil surrounding your ʻāhinahina should be dry most of the time.
ʻĀhinahina does best in a site with full sun for most of the day. Those placed in a shady location will grow slowly (or not at all) and will be less silvery. Too much water or fertilizer will also decrease the silvery color of their foliage.
ʻĀhinahina doesn't grow superfast, so be patient if you want a large shrub. Typically, they increase in height and width by about one foot (30 cm) per year until they reach their mature size (3 to 6 ft; 1 to 2 m). Trying to speed your plant's growth with fertilizer can result in less silvery leaves, so use any type of fertilizer sparingly. ʻĀhinahina can tolerate heat, moderate drought, strong winds, and some salt spray. Plants are also tolerant of hand-pruning. Do so either to remove the occasional dead branch or maintain a desired shape or size. Since ʻāhinahina flowers are not as attractive as its silvery leaves, you may want to prune them away as well to direct more of the plant's energy to leaf growth. See Description above for advice on collecting seeds and rooting cuttings.
Pests and Diseases
In our experience, most pests seem to avoid ʻāhinahina — except for spittlebugs — maybe because of its aromatic leaves. Others have reported occasional problems with mealybugs, scale insects, spider mites, and whiteflies [Lilleeng-Rosenberger 2005; Hawaii Horticulture]. Refer to the Pests & Diseases page for ways to deal with these pests.
Uses
Ancient Hawaiian
According to Ka‘aiakamanu & Akina [1922], ʻāhinahina, mixed with other plant ingredients, was used to treat asthma, lung problems, and high fevers. Recent chemical analysis supports the efficacy of this ancient use [Zant & Gubler 2014]. While several online sources claim that ʻāhinahina was traditionally placed inside large calabashes (‘umeke) with feathered cloaks to protect the cloaks from insects (a reasonable claim), I (Koebele) have yet to find a reliable ethnobotanical source to substantiate this assertion.
Modern
ʻĀhinahina leaves are occasionally used in lei and flower arrangements [Hawaii Horticulture].
Special Features and Information
General
Asteraceae is a very large family — about 32,000 species within 1,900 genera — of mostly herbaceous plants with a subpolar to tropical worldwide distribution. Nearly all Asteraceae have what appears to be a single "daisy" type flower that is actually a composite of several to many much smaller flowers called florets [WikipediA: Asteraceae]. There are about 250 native and non-native Asteraceae in Hawai‘i, with a little more than half being native [Flora of the Hawaiian Islands].
There are about 500 species in the genus Artemisia worldwide. Some well-known non-Hawaiian Artemisia species are: Absinth wormwood (Artemisia absinthium) used to infuse absinthe and other spirits; tarragon (A. dracunculus) used in food; several species of the ubiquitous sagebrush of the American West; and the common mugwort (A. vulgaris) used medicinally for centuries [WikipediA; Artemisia]. Here in Hawai‘i, mugwort is frequently used to flavor and decorate Asian foods like rice cakes and soups.
There are three native species of Artemisia endemic to the Hawaiian Islands: A. australis, found on all the main islands; A. kauaiensis, found on Kauaʻi; and A. mauiensis, found on Haleakalā, East Maui. Some botanists think an ʻāhinahina found on Maui and previously classified as Artemisia mauiensis var. diffusa represents a hybrid between A. australis and A. mauiensis [Wagner et al. 1990].
Two young potted ʻāhinahina: Artemisia mauiensis (left) and Artemisia australis (right). Unfortunately, there are no reliable online images of Artemisia kauaiensis at this time that we can repost.
Hawaiian Name
ʻĀhinahina comes from ʻāhina, which means "gray, gray- or white-haired," referring to the plant's color. Hina also means "gray, gray- or white-haired," with Hinahina meaning "very gray." The added kuahiwi, which means "mountain" [Pukui & Elbert 1986], refers to the plant's montane habitat in contrast to hinahina kū kahakai (Heliotropium anomalum), a silvery native plant that grows near the ocean.
The three native Hawaiian Artemisia species share the names ʻĀhinahina or Hinahina with some other native Hawaiian plants with silvery leaves. ʻĀhinahina and Hinahina are shared with the endemic silversword (Argyroxiphium sandwicense), while Hinahina is shared with several endemic Geranium species, the indigenous hinahina kū kahakai (Heliotropium anomalum), the endemic fern palai hinahina (Hymenophyllum lanceolatum), the endemic hinahina kahakai (Nama sandwicensis), and the indigenous pōhinahina or hinahina kolo (Vitex rotundifolia).
Etymology
The genus name, Artemisia, erected by Carl Linnaeus in 1753, is derived not only from the name of the Greek goddess Artemis (Roman Diana) but also to honor the historical Greek Queen Artemisia II of Caria, who was, among other things, a botanist and medical researcher [Wagner et al. 1990; WikipediA; Artemisia]. The species name, australis, means "southern or pertaining to the south" [Gledhill 2008], possibly to distinguish it from the better-known northern Artemisia species.
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