Charpentiera obovata
Amaranthaceae or Amaranth family
Synonyms: Charpentiera obovata f. grandifolia, Charpentiera obovata f. parvifolia
Charpentiera obovata
Amaranthaceae or Amaranth family
Synonyms: Charpentiera obovata f. grandifolia, Charpentiera obovata f. parvifolia
Pāpala
Broadleaf papala
Natural Range & Environment
Charpentiera obovata is endemic to all the main Hawaiian Islands except Ni‘ihau and Kaho‘olawe. It is found in dry [Joel Lau], mesic, and sometimes wet forests from 190 to 1,750 m (623 to 5,741 ft) [Wagner et al. 1990].
According to Joel Lau, this pāpala species is fairly common in parts of the Wai‘anae Mountain Range of O‘ahu but rare in the Ko‘olau Mountain Range (having been seen by him only at a single site in Maunawili on the windward side of the southeastern Ko‘olau's and in several sites in Wailupe on the leeward side). Additionally, Joel Lau reports seeing numerous Charpentiera obovata x C. tomentosa hybrids, but only in the Wai‘anae Mountains, since in the Ko‘olau Mountains the ranges of the two species do not overlap.
The long panicles of pāpala, with their tiny flowers, can be anywhere from pale yellow to dark red (Photograph of light-colored panicle courtesy of Joel Lau ©; photograph of red panicles courtesy of Forest & Kim Starr CC BY 2.0.). The young leaves of pāpala are often reddish, turning light green as they mature (Photograph of new leaves emerging from trunk courtesy of Forest & Kim Starr CC BY 2.0.) The leaves of Charpentiera obovata have a prominent rib on their margin, most visible on their lower surface (Photograph courtesy of Joel Lau ©.). In the wild, pāpala may not be the prettiest trees. However, when cultivated they can be stunning. Photographs of old wild pāpala at Auwahi, Maui, with Kim Starr (courtesy of Forest & Kim Starr CC BY 2.0), and younger cultivated tree at Haiku, Maui (courtesy of Forest & Kim Starr CC BY 3.0 US).
Description
Charpentiera obovata is a long-lived (greater than five years), often shrubby tree up to 20 feet (6 m) tall. It has thin gray bark and lightweight, very soft and fibrous wood composed of multiple rings of vascular tissue. When dry, branches are extremely flammable and burn like rolled-up paper.
Photograph courtesy of Flora of the Hawaiian Islands ©.
The leaves of Charpentiera obovata are egg-shaped (with the widest point nearest the tip of the leaf) to elliptic and can be anywhere from one to five inches (2.5 to 12.5 cm) long. Young leaves are often reddish, turning light green as they mature but sometimes retaining reddish veins. Both the upper and lower surface of the leaves are typically dull and hairless. There is a prominent rib along the leaf margin, most visible on the lower surface.
Charpentiera obovata produces clusters of tiny flowers on a showy panicle (i.e., branched inflorescence). The species is considered to be gynodioecious, which means some plants have perfect (bisexual) flowers while others produce only pistillate (female) flowers. Panicles can be pale yellow to dark red. Wild plants typically bloom from late spring through early fall, while cultivated plants tend to flower more sporadically. Pollinated flowers develop into utricles (i.e., small thin-walled one-seeded fruits); the seeds are black and shiny.
Growth Requirements
General
The late Greg Koob was one of the first horticulturists to investigate the feasibility of native Hawaiian plants as houseplants; check out his blog, Hawaii Horticulture. While I (Koebele) was unable to discover if Greg ever tested Charpentiera obovata, he did research two other pāpala, C. ovata and C. tomentosa, that grow in habitats not that different from C. obovata. Greg found that both species have low light requirements and did quite well in a room with "fluorescent lights on for most of the day" or a "bright room" (i.e., "north or east-facing room" or "against a wall opposite a south- or west-facing window") [Hawaii Horticulture], and this was before the widespread use of LEDs! Unfortunately, I haven't yet had the opportunity to test how well C. obovata does indoors. However, based on Greg's investigation, I encourage you to try keeping this pāpala species as a houseplant. (If you do, please let us know how it goes by contacting us at EickhoffandKoebele@gmail.com.) I have grown C. obovata outside, and as you can see from the above photograph, they do quite well. Consider using it as an accent in a landscape to highlight its colorful panicles, or, planted several feet apart, as an informal (i.e., lightly pruned) screen or hedge.
As you can see from the above photographs, pāpala can tolerate full sunlight. However, they tend to grow better in a shaded but brightly lit site such as under a tree or the eve of a house; avoid trees that create a deep shade.
Pāpala, both in the ground and in a container, need to have constantly moist soil or media. However, the soil or media also needs to drain water easily. Fortunately, if not sufficiently watered, your pāpala will let you know with wilted leaves or leaves that brown and die along their margins. Pāpala placed in a site that is too hot or too sunny will also display these symptoms. I have only grown pāpala in clay-dominant (but rocky) and organic-dominant soils and media mixes of sphagnum peat moss and lots (i.e., 33%-plus) of black cinders, and, therefore, cannot comment on growth in other soil types. Pāpala can tolerate strong winds without too much damage.
Pāpala grow relatively fast under the optimal conditions described above, and you can expect a three-foot (1 m) tall shrub in two to three years. About this time, also expect to see your pāpala begin to flower. Greg Koob discovered that containerized pāpala growth/size is determined by pot size, and plants can be kept for years in a 4-inch pot. However, he recommends transferring them to a 2- or 3-gallon container in order to let them obtain an attractive houseplant height of three to four feet (1 m), or even larger in 7-gallon pots [Hawaii Horticulture]. Containerized pāpala require regular applications of fertilizer to maintain growth and prevent yellowing leaves. To meet this need, apply a balanced controlled-release fertilizer with minor elements every six months, or use an organic or inorganic foliar fertilizer diluted to ⅓ to ½ the recommended strength every month.
Pāpala can be pruned by hand, but do so only to remove dead (or pest-infested) branches or maintain a desirable shape. Avoid over-pruning and never use a hedge trimmer. Rather than discarding the pruned (live and healthy) branches, consider rooting them to create new plants for your friends. Pāpala cuttings take one to two months to root when kept in a high humidity environment (see Native Hawaiian Garden).
Pests and Diseases
Pāpala is prone to infestations by aphids, mealybugs (both above and below the soil/media), scale insects, and spider mites. Outdoors, these pests are often farmed and protected by ants. Indoor pāpala are particularly susceptible to spider mites because of the dry, windless environment. Refer to Pests & Diseases for ways to combat each of these pests.
Uses
Ancient Hawaiian
Frequently quoted, Isabella McHutcheson Sinclair (1840–1890), in her 1885 book, Indigenous Flowers of the Hawaiian Islands, perfectly describes how Hawaiians used pāpala for aerial fireworks.
"The wood is very light and porous, and being easily ignited, is used by the natives for most original and grand displays of fireworks. On the north-west side of Kauai the coast is extremely precipitous, the cliffs rising abruptly from the sea to a height of from one to two thousand feet, and from these giddy heights, the ingenious and beautiful pyrotechnic displays take place. On dark moonless nights, upon certain points of these awful precipices — where a stone would drop sheer into the sea — the operator takes his stand with a supply of papala sticks, and lighting one, launches it into space. The buoyancy of the wood, and the action of the wind sweeping up the face of the cliffs, cause the burning wood to float in mid-air, rising or falling according to the force of the wind, sometimes darting far seaward, and again drifting towards the land. Firebrand follows firebrand, until, to the spectators (who enjoy the scene in canoes upon the ocean hundreds of feet below) the heavens appear ablaze with great shooting stars, rising and falling, crossing and recrossing each other, in the most weird manner. So the display continues until the firebrands are consumed, or a lull in the wind permits them to descend slowly and gracefully to the sea."
According to Krauss [1993], this sport of tossing firebrands was called ʻōahi, and sometimes the spectators in the canoes below would attempt to catch the burning embers before they fell into the ocean and brand (i.e., tattoo) themselves to commemorate the event.
Medeiros et al.[1998] notes an unpublished 1967 Auwahi Forest Report; Appendix 6, by Lennox in which he wrote of this species, “Wood soft — burns like paper — used for torches.”
Modern
Pāpala panicles are sometimes used in lei-making [Maui Magazine].
Special Features and Information
General
The Amaranth family (Amaranthaceae) is a large family with about 2,040 species within 165 genera, most being herbs or shrubs with a few trees and vines. They are found in tropical to cool temperate regions with a few, like spinach (Spinacia oleracea) and beet (Beta vulgaris) being economically important vegetables [WikipediA;Amaranthaceae].
Charpentiera is a small genus with five species endemic to Hawai‘i [Flora of the Hawaiian Islands], and one species, C. australis, found in the Austral and Cook Islands [Wagner et al. 1990].
In addition to Charpentiera obovata, other native Hawaiian members of Amarantheceae include: one extinct and five endemic species of Achyranthes; a rare and endangered (and possibly extinct) amaranth (Amaranthus brownii) seen only on Nīhoa; another rare endemic amaranth (Amaranthus pakai) last seen on Hawai‘i Island; four additional endemic pāpala species (Charpentiera spp.); and the endemic ʻāweoweo (Chenopodium oahuense) [Flora of the Hawaiian Islands].
The Pu‘u wa‘awa‘a Biological Assessment [2021 revision], page 35, reports that the endemic Hawaii Elegant Long-horned Beetle
(Plagithmysus elegans) "was only found on papala trees, a species that is almost extirpated at PWW." Since Hawai‘i's many endemic species of long-horned beetles are known to be plant host specific, this suggests that Charpentiera obovata is essential for P. elegans continued existence since C. obovata is the only pāpala species found at Pu‘u wa‘awa‘a.
Hawaiian Name
The word pāpala can also mean "firebrand," or more rarely mean "haze, fog; hoarse, as the voice" [Pukui & Elbert 1986].
Etymology
The genus name, Charpentiera, was given by French botanist Charles Gaudichaud-Beaupré (1789–1854) to honor Jean G. F. de Charpentier (1786–1855), a German-born Swiss geologist, conchologist, botanist, and fellow voyager with Gaudichaud on the Uranie [Wagner et al. 1990]. The species name, obovata, is Latin, meaning "egg-shaped in outline with the narrow end lowermost" [Gledhill 2008], referring to the leaves being egg-shaped with the widest point nearest the tip of the leaf; often considered the opposite of the leaf term ovate, where an egg-shaped leaf has its widest point nearest the base of the leaf.
BPK