Native Plants of Hawai‘i - Pittosporum confertiflorum

Pittosporum confertiflorum

Pittosporaceae or Pittosporum family

Synonyms: Pittosporum cauliflorum, Pittosporum cauliflorum var. cladanthoides, Pittosporum cauliflorum var. fulvum, Pittosporum cauliflorum var. macrophyllum, Pittosporum cauliflorum f. pedicellatum, Pittosporum cauliflorum var. pedicellatum, Pittosporum cauliflorum var. reticulatum, Pittosporum cladanthum, Pittosporum cladanthum var. fulvum, Pittosporum cladanthum var. gracilipes, Pittosporum cladanthum var. reticulatum, Pittosporum cladanthum var. skottsbergii, Pittosporum confertiflorum f. longipes, Pittosporum confertiflorum var. longipes, Pittosporum confertiflorum var. mannii, Pittosporum confertiflorum var. microphyllum, Pittosporum halophiloides, Pittosporum lanaiense

Hōʻawa

Hāʻawa

Wai‘anae Range cheesewood

Natural Range & Environment

Pittosporum confertiflorum is endemic to Oʻahu, Lānaʻi, Maui, and Hawaiʻi Island. It has a wide environmental range, being found in dry to wet forests, from the lowlands to the subalpine, 180 to 2,200 m (591 to 7,218 ft) [Wagner et al. 1990].

Hōʻawa flower clusters can emerge near the stem-tips or lower down along the branch (Flower photographs here and in header courtesy of Forest & Kim Starr CC BY 3.0 us). Hōʻawa fruits split open when ripe to reveal their sticky black seeds, supposedly a favored food of the endangered ʻalalā or Hawaiian crow (Corvus hawaiiensis) (Photograph courtesy of Michael Sthreshley CC BY-NC 4.0). Depending on their origin and age, hōʻawa can have very fuzzy or nearly hairless leaves. The color of the hairs can also vary from rusty brown to white. Here you can see both a flush of fuzzy new leaves and a mature leaf that has retained its fuzzy undersurface (New leaves photograph courtesy of Kevin Faccenda CC BY 4.0); Mature leaves photograph courtesy of Kyhl Ausitn CC BY-NC 4.0). Two cultivated hōʻawa, one in a private residential yard and the other on a public campus (Public campus photograph courtesy of jordan212 CC BY-NC 4.0).

Description

Pittosporum confertiflorum is a shrub to small tree up to 30 feet (9 m) tall [Wagner et al. 1990] that has a lifespan much longer than five years; however, we have never seen this hōʻawa species much more than about ten feet (3 m) tall. Hōʻawa has thick obovate leaves with a rolled margin and impressed veins on their upper surface and slightly raised veins on their underside. Leaves can vary in size but are usually 3 to 6 inches (7.6 to 15 cm) long. Often, the leaves are densely covered in reddish brown to light brown (less often white) hairs, particularly when young, becoming hairless (or nearly so) on their upper surface as they mature; the lower surfaces usually remain quite hairy.

Clusters of small cup-shaped 5-petal bisexual (or rarely unisexual) flowers develop near the tip of the stem or lower down along the branch. The flowers' petals are usually off-white to pale yellow.

Hōʻawa capsules (i.e., fruits), which look a lot like walnuts, develop and mature slowly, turning from green to dark brown or black when ripe. They then split open, without any warning (as far as we can tell), to reveal their bright yellow to red, most often orange, interior packed with a few dozen viscous black angled seeds. Be aware that Hawaiian Pittosporum can hybridize [Bacon et al. 2011], and, therefore, you should follow a strict protocol if you intend to grow new plants from collected seeds; see Pritchardia martii for how to do this.

Growth Requirements

General

Pittosporum confertiflorum, with its often fuzzy, always-attractive leaves, is a great addition to a landscape. Use it as an accent or, planted several feet apart, as an informal (i.e., very lightly pruned) screen or hedge. The deep shade it produces can provide habitat underneath for sun-sensitive plants like ferns. It can also be kept as a container plant; however, if not periodically transferred to a larger container, hōʻawa will become potbound and stunted.

Hōʻawa grows well both in a site with full sunlight all or most of the day, as well as a partially or lightly shaded location, provided it receives enough water. Watering will require a bit of experimentation on your part, depending on how much rainfall, sunlight, heat, and wind your hōʻawa is exposed to. Generally, you should try to keep the surface soil dry most of the time and the subsurface (one or two inches down) soil moist all of the time.

Leland Miyano, a local landscape architect and artist, who has probably grown more hōʻawa than anyone, recommends disturbing a hōʻawa's roots as little as possible when planting it in the ground or transferring it to a new pot. Hōʻawa will grow in lava/cinder, clay, and organic-dominant soils, as long as the soil drains water well. We have not tried to grow hōʻawa in sandy or coralline soils.

Hōʻawa tends to grow in spurts at a slow to moderate pace, putting out whorls of fuzzy new leaves rather than one leaf at a time. Under optimum conditions, expect your plant to grow about a foot (30 cm) taller each year and begin flowering after about five years. Prune it only to remove dead branches. Again, be aware that Hawaiian Pittosporum can hybridize [Bacon et al. 2011], and, therefore, you should follow a strict protocol if you intend to grow new plants from collected seeds; see Pritchardia martii for how to do this.

Pests and Diseases

Hōʻawa are prone to scale insect infestations, often farmed and protected by ants, and spider mites (look for them on the undersurface of the leaves). Less often, other sap-sucking pests such as aphids and mealybugs will attack hōʻawa. The honeydew produced by these pests often results in a sooty mold growing on the leaves and stems. Refer to the Pests & Diseases page for ways to battle each of these pests.

Uses

Ancient Hawaiian

Hōʻawa wood was used to make the gunwales of canoes [Krauss 1993]. Hawaiians also supposedly used the outer layer of hōʻawa fruit valves by pounding them up and applying them externally to sores [Neal 1965]. Ka‘aiakamanu & Akina [1922] describe a somewhat similar use to that described by Neal [1965] for a "scrofulous swelling about the neck," but the treatment includes other plants pounded along with the "meat" of hōʻawa fruits. Ka‘aiakamanu [2003] also describes Hawaiians with "priestly knowledge" using hōʻawa to "bathe someone who is thought to be sick or perhaps visited by ghost."

Modern

Special Features and Information

General

Pittosporaceae is a small family of about 240 species within nine genera that are limited to tropical and temperate Africa, Australia, Indo-Malaysia, and Oceania [WikipediA;Pittosporaceae]. In Hawai‘i, there are 11 native Pittosporum species, all endemic, with P. confertiflorum and P. glabrum being the most widespread and common [Flora of the Hawaiian Islands].

Rock [1974] noted that the endemic (and now critically endangered) ʻalalā (Corvus hawaiiensis; Hawaiian crow), which was still very common in the 1910s, would peck at the capsules of Pittosporum hosmeri, a hōʻawa endemic to Hawai‘i Island, and eat the oily seeds inside.

Hawaiian Name

Etymology

Pittosporum is derived from the Greek words, pitta, meaning "tar" or "pitch," and sporos, meaning "seed," referring to the sticky film of resin covering the seeds [Gledhill 2008]. The species name, confertiflorum, is from the Latin words, confertus for "dense" or "crowded," and flora for "flowers," referring to the species' dense cluster of flowers [Gledhill 2008].

BPK