Native Plants of Hawai‘i - Nothocestrum latifolium

Nothocestrum latifolium

Solanaceae or Nightshade family [Five-minute families]

Synonyms: Nothocestrum subcordatum

‘Aiea

Hālena

Broadleaf ʻaiea

Natural Range & Environment

Nothocestrum latifolium is an endangered tree endemic to Hawai‘i found in dry to mesic forests, shrublands, and grasslands. Historically, it also grew in wet forests, shrublands, and grasslands [ECOS].

On Kaua‘i, Nothocestrum latifolium was collected only once in ‘ōhi‘a and olopua (Metrosideros sp. and Notelaea sandwicensis) forest at 1,140 m (3,740 ft) in 1986 but has not been seen since. However, this observation is questioned by some botanists who think the collected specimen might actually be N. longifolium. On O‘ahu, the last wild tree died in 2012. It was in mesic lama (Diospyros sandwicensis) forest in the Wai‘anae Mountains. On Lāna‘i, the species occurred in dry to mesic forest from 500 to 518 m (1,640 to 1,699 ft) along with lama (Diospyros sandwicensis) and olopua (Notelaea sandwicensis). However, a 2011 survey was unable to find any living wild plants. No living wild N. latifolium are currently (2021) known on these three Islands [USFWS 2021].

According to the last USFWS 5-Year Review [2021], there are still wild and living Nothocestrum latifolium on Moloka‘i and Maui. On Moloka‘i, the species is rare but still occurs in dry forest and mesic shrubland and grassland. On Maui, the species is more common, and can be seen on the dry southern slopes of Haleakalā, East Maui, and in wetter ‘ōhi‘a and lama (Metrosideros sp. and Diospyros sandwicensis) forest in West Maui.

Nothocestrum latifolium was federally listed as endangered in 2012. At that time, there were an estimated 1,600 wild plants on O‘ahu, Moloka‘i, and Maui. By 2021, that estimate was dramatically reduced to six wild trees on Moloka‘i, and 132 to 133 plants on Maui. Fortunately, there have been numerous restoration plantings (over 2,000) since 2006, most as part of the Auwahi Forest Restoration Project, with moderately good (i.e., about 70%) survivorship. Additionally, some populations are protected from ungulates by fencing and benefit from alien plant control activities [USFWS 2021].

‘Aiea flowers have a sweet lemony fragrance, particularly en masse (photograph courtesy of Danielle Frohlich CC BY-NC 4.0). ‘Aiea leaves can vary in color, size, and shape. In particular, the leaves of cultivated plants (pictured here between two branches) tend to be larger, thinner, and a lighter shade of green than those of wild trees (photograph of leaves with scalloped margin courtesy of Forest & Kim Starr CC BY 3.0; photograph of leaves with non-scalloped margin courtesy of Kenneth R. Wood (NTBG) CC BY-NC 4.0). ‘Aiea has light gray bark, often gnarled or damaged (by ungulates) and covered with lichens (photograph courtesy of Forest & Kim Starr CC BY 3.0). A young ‘aiea planted out as part of the Auwahi Forest Restoration Project on the southern slopes of the Haleakalā, Maui, along with other smaller native plantings (photograph courtesy of Forest & Kim Starr CC BY 3.0). An old wild ‘aiea, growing in Auwahi rangeland; the orange color in the tree's canopy is epiphytic lichens (photograph courtesy of Forest & Kim Starr CC BY 3.0).

Description

Nothocestrum latifolium is a long-lived (greater than five years) small tree (to about 33 ft [10 m]) with soft gray bark that is often furrowed or scarred (by ungulates) on older trees. Its branches, particularly on young trees, often grow at an extreme ascending angle. Joseph Rock, author of the seminal 1913 book, The Indigenous Trees of the Hawaiian Islands, called ‘aiea "the most ugly trees which the Hawaiian Islands possess" [Rock 1974 Reprint of 1913 book]. This assessment was at least partially because, as Rock notes, the soft bark of the trunk and branches were often eaten by thirsty cattle, leaving the trees with prominent scars. Not to dismiss Rock's opinion, but we do not think ‘aiea is "ugly."

Nothocestrum latifolium leaves can vary in shape, from broadly egg-shaped to elliptic, and in size, from 1.5 to nearly 8 inches (4 to 20 cm) long [Wagner et al. 1990]. Leaf margins are most often scalloped or irregularly lobed but can also be entire. Leaf color can vary from light to medium green, with the midrib nearly always a lighter color than the rest of the leaf. Wild trees tend to have thicker leaves than cultivated plants. While wild trees are seasonally deciduous, shedding many of their leaves when the weather becomes dry, cultivated plants seem to drop their leaves more sporadically.

The small clustered flowers of Nothocestrum latifolium are perfect (bisexual), with four greenish-yellow petals that extend beyond the tubular calyx (fused sepals). They have a sweet lemony fragrance, particularly en masse. Wild trees have been observed with flowers nearly year round [ECOS].

Nothocestrum latifolium has small round berries that turn yellowish orange when ripe, often with the lower portion enclosed by the flower's calyx. Within the small fruit are a few to several small irregularly-shaped yellow seeds [Lyon Arboretum].

Growth Requirements

General

I (Koebele) have repeatedly tried and failed to grow this species of ‘aiea, never getting my saplings taller than three feet (1 m); I've had better luck with Nothocestrum breviflorum. David (Eickhoff) has had fewer but more successful attempts, once growing a sapling to about nine feet ( 3 m) tall in his yard before it was killed by an unidentified borer. Unfortunately, David's plant never flowered. The only people we know having real success growing Nothocestrum latifolium are those associated with the Auwahi Forest Restoration Project (AFRP). Since 2006, they have been able to propagate, grow, and plant over 2,000 N. latifolium within their managed restoration areas. Below is a summary of what David and I have personally learned, along with what I think may be two key environmental differences that explain the repeated success of AFRP and my many failures.

‘Aiea is best placed as an accent in the landscape since it produces little shade. However, because of its slow growth and numerous pests, you should also consider keeping it in a container, periodically transferring it to larger and larger pots as it grows. It does best in a site with full sunlight for all or most of the day. When first planted, you should water it regularly (once or twice a week) until you see consistent new growth. You can then cut back on the watering such that the surface soil is dry most of the time (but still moist a few inches down). ‘Aiea often experiences transplant shock when planted out and will drop all or most of its leaves. Don't panic! Reduce your watering to just enough to keep the soil moist, and it will likely "come back to life" in a few weeks with some new leaf buds.

‘Aiea is a slow-growing tree that tends to grow in spurts, only increasing in height 6 to 12 inches (15 to 30 cm) each year. Also, even out in the open, young plants tend to grow straight up with their few branches strongly angled upward. My in-the-ground ‘aiea would "green up" a bit if fertilized, but never seem to grow any faster than unfertilized plants. Take care when fertilizing your potted ‘aiea since the fertilizer may shock it, causing your plant to lose all or most of its leaves; apply only the minimum amount to keep the plant's leaves green or use a controlled-release granular fertilizer. ‘Aiea can endure drought, heat, and strong winds. Because ‘aiea grows slowly, avoid pruning your tree except to shorten unusually long branches that might break in a windstorm.

Now, why have I repeatedly failed and AFRP repeatedly succeeded with Nothocestrum latifolium? First, I suspect the difference in soil temperatures, particularly at night, might be the reason. Auwahi, Maui, is considerably cooler than the lowlands of Wai‘anae and Pearl City, the two locations I have grown N. latifolium. John Culliney and I discovered long ago that several native Hawaiian tree seedlings in pots would experience a growth stasis during the hottest months of the year [Culliney & Koebele 1999]. Without doing the proper experiments, we attributed this to the increased media temperature in the pot. If I am correct, then, the best place to grow N. latifolium is in the cooler uplands of any of our Islands.

Second, Auwahi is a semi-natural site. While greatly disturbed by ranching, it still contains many native Hawaiian plants, and has not experienced any significant urbanization. This has likely limited the transport and establishment of introduced alien and harmful soil pests and microbes. In contrast, all my ‘aiea plantings were in sites that have a history of profound habitat destruction and modification. Therefore, it's possible that N. latifolium is particularly vulnerable to attacks by harmful alien soil pests and microbes. However, this does not readily explain why my potted ‘aiea also grew poorly, unless the pest or microbe is extremely ubiquitous in lowland areas. In order to "prove" this hypothesis, it is essential that we all do our due diligence in the future and conduct a rigorous autopsy of any dead potted ‘aiea, including sending samples to the University of Hawai‘i at Mānoa Agricultural Diagnostic Service Center for analysis. If you have had the opportunity to grow N. latifolium and feel you can add to the discussion above, please contact us at EickhoffandKoebele@gmail.com so we might improve the content of this webpage.

Pests and Diseases

When small (i.e., less than two feet [61 cm] tall), ʻaiea is often attacked by broad mites, flea beetles, mealybugs, scale insects, and spider mites. Fortunately, larger plants seem to be much less susceptible to these attacks with the possible exception of scale insects and mealybugs. If you encounter any of these pests on your ʻaiea, refer to the Pests & Diseases page for methods to deal with them.

Near their base, ‘aiea are sometimes attacked by chewing pests such as millipedes, cockroaches, snails and slugs, etc. Small plants can be quickly girdled and die. Therefore, inspect this area frequently for damage. If you see any, apply a broad-spectrum long-lasting granular pesticide and protect the lower stem with a modified plastic bottle or similar device (see Pest & Diseases; Rats and Mice).

Nothocestrum latifolium is adapted to the dry, easy-draining substrate of lava fields in the leeward regions of our Islands. Therefore, poor-draining soil or overwatering can result in fatal consequences.

One noteworthy "pest" you are unlikely to see on your ‘aiea is the larva of the Blackburn's sphinx moth (Manduca blackburni). ‘Aiea are believed to be the native natural host of this endangered moth [ECOS]. Today, because of the rarity of ‘aiea, you are more likely to see this endemic moth on or flying around the introduced and naturalized tree tobacco (Nicotiana glauca). Obviously, if you see a Blackburn's sphinx moth on your ‘aiea (or elsewhere), DO NOT kill it! Consumed leaves is perhaps the least of your worries in trying to keep your ‘aiea alive. Also, killing a Blackburn's sphinx moth is against the law!

An endangered Blackburn's sphinx moth (Manduca blackburni) larva eating the leaves of the introduced and naturalized tree tobacco (Nicotiana glauca) (photograph courtesy of Forest & Kim Starr CC BY 3.0). This is the green form; there is also a gray-brown form.

A female endangered Blackburn's sphinx moth (Manduca blackburni) (photograph courtesy of The Trustees of the Natural History Museum, London, CC BY 3.0).

Uses

Ancient Hawaiian

Krauss [1993] states that while ‘ahakea (Bobea spp.) was preferred, ‘aiea wood was sometimes used to make the pale (gunwales) of wa‘a (canoes). Both Rock [1974 Reprint of 1913 book] and Malo [1898/1903] state something similar. Rock states “The wood of this, as well as of the other species, is soft and of a green color; it was used by the natives in the olden days for finishing off canoes." He also wrote that "The reddish yellow berries are sometimes eaten." Malo wrote, "The manono and aiea were trees that also furnished canoe-timber."

Pukui & Elbert [1986] state that "One slender species was used for thatching sticks (‘aho) and fire-making." However, they do not provide any citation(s) for this claim.

Ka‘aiakamanu & Akina [1922] state that the "ripe leaves, together with the bark and tap-root are employed for the cure of ulcers and scrofulous sores," as well as noting that ‘aiea wood was used to make the "end pieces" of canoes.

Modern

Special Features and Information

General

Nothocestrum latifolium is in the Nightshade family (Solanaceae), which has about 103 genera and 2,700 species worldwide. The family contains numerous edible species, such as tomato (Solanum lycopersicum), potato (Solanum tuberosum), and eggplant (Solanum melongena). However, it also contains some extremely deadly plants with sometimes sinister names like: the Apple of Sodom, Angel's trumpet, Porcupine tomato, Thorn apple, Devil's fig, Devil's apple, and Five-Minute plant. Other relatives containing toxic chemicals are: mandrake (Mandragora officinarum), Jimsonweed (Datura stramonium), and tobacco (Nicotiana spp.). The "Queen of Toxins," and one of the deadliest is Belladonna (Atropa belladonna), which contains tropane alkaloids. It is also called Devil's Berries, Death Cherries, or Deadly Nightshade [WikipediA;Solanaceae].

Other native Hawaiian Solanaceae include: the indigenous ʻōhelo kai (Lycium carolinianum var. sandwicense); three additional endemic species of ʻaiea (Nothocestrum spp.); and five Solanum species [Flora of the Hawaiian Islands].

In addition to the rare and endangered Nothocestrum latifolium, there are three additional Nothocestrum species, all called ‘aiea.

Nothocestrum breviflorum: A rare and also endangered small tree endemic to Hawai‘i Island [ECOS].
Nothocestrum longifolium: A more secure shrub to small tree seen primarily in wet forests but also sometimes in mesic forests on all the main Hawaiian Islands except for Ni‘ihau and Kaho‘olawe [Wagner et al. 1990].
Nothocestrum peltatum: Another extremely rare and endangered small tree seen in the mesic forests of Kaua‘i. Currently (2022), there are only about 30 known wild trees [ECOS].

Hawaiian Name

‘Aiea is a common placename in south-central O‘ahu. Examples include: a land section, mill, village, bay, stream, field, recreation center, and schools. It is also the name of a native holly on Kauaʻi (Ilex anomala), called kāwaʻu on the other Hawaiian Islands. Lastly, ‘aiea can also mean "exhaustion, fatigue, or weariness" [Ulukau].

Pukui & Elbert [1986] state that hālena is the "Same as ‘aiea."

Etymology

Nothocestrum is derived from the Greek word, nothos, meaning "false," and Cestrum, the name for a large American plant genus [Wagner et al. 1990]. In turn, the etymology of cestrum is uncertain, but is likely derived from the Greek word kestron (κέστρον), which has several meanings [Wiktionary;cestrum].

The species name, latifolium, is a composite of the Latin words, latus, meaning "broad" or "wide" [Latdict], and folium, meaning "leaf" [Latdict], referring to the broad or wide leaves of this species.

BPK