Page last updated 04OCT2018
Pittosporum hosmeri
Plant Family
Pittosporaceae
Binomial Name
Pittosporum hosmeri Rock.
Alternate Binomial Names
Pittosporum amplectens
Common (Vernacular) Names
Kona cheesewood, Kona hoawa, Hawaiian magnolia
Hawaiian: Hō’awa. Lesser known names include hā’awa, papahekii, hō’awa lau nui, ‘a’awa, ‘a’awa hua kukui, a’awahua.
Plant Characteristics
Endemicity. This plant is found in the mesic to wet forests on the leeward (dry side) of the island of Hawaiʻi, from the Kohala Mountains south through the Kaʻū District from about 1,250 to over 3,500 feet in elevation.
It is one of the predominant tree species found in the near-pristine Native Hawaiian dryland forest property held by the nonprofit organization Ho’omalu Kaʻū and the adjacent Manukā Natural Area Reserve of the State of Hawaiʻi (Vance 2015 et al.).
Growth Habit. A slowly growing shrub or small tree from 3-8 meters in height at maturity.
Flowers. Female and male flowers are formed on separate plants and are borne in clusters. Most of the clusters form directly on the branches of the tree. The flowers are fragrant at night, suggesting the purpose of the fragrance may be to attract pollinators active at night. hō’awa may bloom throughout the year and both flowers and maturing capsules may be present on the tree at the same time.
 Pittosporum hosmeri Pendant Flower Cluster |
 Pittosporum hosmeri Inflorescence |
 Pittosporum hosmeri(Hō’awa) Single Flower |
Pods (Capsules). The fruits or pods (capsules) are hard, woody and tend to be somewhat cubed-shaped. Unripe pods are dark green. As they ripen they turn yellow-orange and then to brown, and open. The inner surfaces of the ripe capsules are golden-orange. The capsules on each tree vary somewhat in size but on most of our trees they are about 20-30mm in length. Some trees consistently form larger, more cubic pods about 40mm in length. The trees with different capsule sizes may represent two varieties of the plant.
 Hō’awa Capsules and Flowers |
 Comparison of Seed Capsule Sizes |
Seeds. The capsules contain about 10-45 black seeds arranged in two rows. When the pods open naturally the seeds are usually covered with an oily material. Occasionally, some capsules contain seeds with radicles (embryonic roots) extending from them as if they were beginning to germinate. The seeds from the small capsuled variety have an average weight 0.03g each, those from large capsules 0.04g.
 Seeds of Pittosporum hosmeri |
Albinism. About 5% or less of newly emerged seedlings from our plantings of seed from this species appear to be albinos. Albinism is caused by a fatal gene mutation that results in plants lacking chlorophyll and the ability to make sugars. Albino hō’awa seedlings die 2-3 weeks after germination.
 Albino Pittosporum hosmeri Seeding |
Conservation Status
Pittosporum hosmeri is not currently considered threatened but populations of the tree are probably declining over much of its former range with the losses of the Hawaiian dry forests. Introduced pests, particularly ants and rats, and the extinction of the Hawaiian crow, important for disbursal of its seeds, may be contributing to these declines. The closely related Hawaiian species Pittosporum hawaiiense, also endemic to Hawaiʻi Island, is now listed as an endangered species (FWS 2013).
CITES Listing: This species was not found on CITES Appendices I, II or III (CITES 2018).
IUCN Listing: No assessment of this species has been reported on the IUCN Red List of Threatened Species™ [IUCN 2018].
Endangered Species Act Listing Status: Not listed (FWS 2018).
Relationship to Other Endangered Species: The critically endangered Hawaiian crow or ʻalalā (Corvus hawaiiensis), is a very intelligent native bird species that was revered in Hawaiian culture and is now largely extinct in the wild. Birds from a captive breeding program are now being reintroduced into the wild on Hawaiʻi Island Reserve lands (DLNR 2018). The oily seeds of the hō’awa were a component of the crow’s diet. The birds were attracted to the orange color of the opening capsules and with their chisel like beaks they were able to peck open the woody pods and eat the seeds. The oily coating of the seeds provided nutrients to the bird and the seeds, probably activated by the bird’s digestive processes, were spread around the range of the birds in droppings. Populations of hō’awa in the former range of the Hawaiian crow are becoming very scarce as a result of the crow’s disappearance.
“Hō’awa embodies the symbiotic relationship between flora and fauna in Hawaiʻi’s fragile environment and is a classic example of how inter-dependent native Hawaiian plants and animals are in the natural ecosystem”(Vance 2015).
Uses
Hō’awa had multipole cultural uses in early uses in early Hawaiʻi and it is now becoming recognized as one of the best native plants for use in landscaping.
Landscaping. An excellent native Hawaiian tree for landscaping use as a specimen tree, accent or screen. It can be planted about three feet apart and maintained as a hedge. The trees can be grown in full or partial sun, require little care and are wind, vog and drought tolerant once established. Some references indicate that the trees are not salt tolerant but ours are doing very well in an area receiving considerable salt fallout from sea spray carried by trade winds.
Hō’awa can be grown in close proximity to invasive Christmas berry trees (Shinus terebinthifolius) and are apparently not affected by the allopathic substances they release to soils that may suppress growth of other plant species.
 Hō’awa (Pittosporum hosmeri) Planted as a Hedge |
Wildlife Habitat. Replanting hō’awa in the previous range of the Hawaiian crow may provide a critical food source for the birds and be helpful in efforts to reintroduce the species.
Traditional Medicinal Uses. The outer layer of the capsules was pounded and used externally on sores. In mixtures with other botanicals it was used as a liquid massage for swollen necks and similar ailments (Vance 2015). We have submitted specimens of materials to be tested for antimicrobial activity at the University of Hawaii, College of Pharmacy.
Wood. In early Hawaii wood from the tree was used in canoes for gunwales, as firewood and other practices by kāhuna.
Cultivation
This plant is not widely cultivated. Occasionally, small inventories of the plant are available from nurseries in Hawaiʻi.
Propagation
Seeds. Hō’awa seeds are reportedly short-lived and lose their viability in storage. Seeds harvested for planting should be taken from capsules that are ripe and have opened on their own. Planting recommendations vary significantly among references. For those attempting to grow hō’awa from seeds, patience is a necessary virtue as they can take 3-12 months to germinate. Various treatments have been recommended to hasten germination including soaking overnight in tap water, bleach solutions etc. We have an experiment in progress to test other treatments simulating bird digestive processes but do not expect to have results for several months. References also recommend the use of sterilized planting media, and various mixtures of vermiculite, peat moss, perlite etc. From our experience, none of these are necessary. We have produced many seedlings from untreated seed sewn in flats on sifted native cinder soil. Any well-draining planting media may suffice.
Cuttings: This species can be propagated from semi-hardwood cuttings (Lilleeng-Rosenberger 2005). Rooting is a slow process taking 3-5 months.
Pests and Diseases
These trees have no significant diseases but can be damaged by pests.
Ants and Their Insect Farms. All ants Hawaiʻi are introduced invasive species. Ants nesting at the base of hō’awa trees may weaken them. The ants also farm mealy bugs, scale insects and aphids that may transmit viruses to the plant (Lilleeng-Rosenberger 2005). We have observed the little black ant (Monomorium minimum) tending mealy bugs and aphids on our trees. The aphids are most common on leaf buds and new foliage; mealy bugs are found most frequently on the bases of the capsules and are actively tended by the ants. The ants and the insects they farm have not done significant damage to the trees so far.
Rats. Rats seek out and consume the seeds and unripe capsules. In 2016-2017 season we lost our entire crop of hō’awa seeds due to rats. With the implementation of ongoing rat control measures no damage to the seed capsules has been observed.
 Rat Damage to Unripe Pittosporum hosmeri (Hō’awa) Capsules |
Birds. Other bird species will consume the seeds and emerging seedlings. We have observed the red-crested cardinal (Paroaria coronata), a songbird species from South America introduced into Hawaiʻi, consuming emerging seedlings of hō’awa.
Slugs and Snails do not attack hō’awa trees.
Invasiveness Potential
This plant is endemic to the island of Hawaiʻi. A weed risk assessment was not performed.
Plants and Seeds for Sale
Availability
Seeds. All of the seeds that we offer are from trees in artificial cultivation on our Discovery Harbour site. Seed lots from small and large capsuled varieties will be available for sale from our online store by mid-October 2018. All seeds offered will be from ripe, naturally opened pods and unprocessed with their oily coatings intact. Most of the seeds will be from September 2018 harvest and additional, smaller seed lots may be available from October and November. The seeds should planted immediately upon receipt.
Nursery Stock. We have produced hundreds of potted seedlings of this species for local sale, fundraisers and donation to the Nature Conservancy, Amy B. H. Greenwell Ethnobotanical Garden and other organizations. In 2016 our inventory was totally depleted. To maximize genetic diversity we do not grow this plant from cuttings. It will take 2-3 years to grow new plants from the new seed lots produced in September 2018. We will attempt to grow certified seedlings for export and non-certified plants for planting in Hawaiʻi. Demand is expected to far exceed our supply.
Improved Cultivars. Improved cultivars of this species are not available.
Shipping Information
Hō’awa seeds can be exported to all destinations but must be inspected before shipment.
Certified hō’awa seedlings may be shipped to all states in their artificial growing media.
Non-certified seedlings cannot be shipped to the Hawaiʻi quarantine states of AZ, CA, LA and TX. They can legally be shipped to the other Hawaiian Islands and to the remaining states but must be shipped bareroot. Hō’awa have fine roots and that are difficult to completely remove from adherent soil as required by shipping regulations. They are likely to be severely damaged by soil removal and may not survive shipping. For these reasons we do not recommend shipping of non-certified plants.
References
CITES (Convention on International Trade in Endangered Species of Wild Faoua and Flora). Appendices I, II, and III valid from 4 October 2017. https://www.cites.org/eng/app/appendices.php [accessed 03 October 2018].
CTAHR (College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa). Hawaiian Native Plant Propagation Database: Pittosporum hosmeri. http://www2.hawaii.edu/~eherring/hawnprop/pit-hosm.htm [accessed 03 September 2018]
DLNR (Hawaiʻi Department of Land and Natural Resources). 2018. The ʻAlalā project: restoring Hawaiʻi’s native crow to the wild. https://dlnr.hawaii.gov/alalaproject/ [accessed 03 October 2018].
FWS (U.S. Fish and Wildlife Service). 2013. Endangered and threatened wildlife and plants; determination of endangered species status for 15 species on Hawaii Island; Final rule. Federal Register 78(209): 64638-64690. https://www.gpo.gov/fdsys/pkg/FR-2013-10-29/pdf/2013-24103.pdf
FWS (U.S. Fish and Wildlife Service). 2018. Endangered Species Home. Search Endangered Species Database. https://www.fws.gov/endangered/ [accessed 03 October 2018].
IUCN (International Union for Conservation of Nature). 2018. Version 2018-1. The IUCN Red List of Threatened Species™. http://www.iucnredlist.org/search [accessed 03 October 2018].
Lilleeng-Rosenberger KE. 2005. Pittosporaceae. In: Growing Hawai’i’s Native Plants. MH Chapin, Ed. Honolulu, HI: Mutual Publishing, LLC.
UH (University of Hawaii) 2009. Native Plants Hawaii. Pittosporum hosmeri. University of Hawaii. http://nativeplants.hawaii.edu/plant/view/Pittosporum_hosmeri . [accessed 03 October 2018].