Wiliwili | |
---|---|
Raceme of wiliwili | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Fabales |
Family: | Fabaceae |
Subfamily: | Faboideae |
Genus: | Erythrina |
Species: | E. sandwicensis |
Binomial name | |
Erythrina sandwicensis | |
Wiliwili (Erythrina sandwicensis) is a species of tree in the pea family, Fabaceae, that is endemic to the Hawaiian Islands. It is the only species of Erythrina that naturally occurs there. It is typically found in Hawaiian tropical dry forests on leeward island slopes up to an elevation of 600 m (2,000 ft).
Wiliwili means "repeatedly twisted" in the Hawaiian language and refers to the seedpods, which dehisce, or twist open, to reveal the seeds.
Wiliwili trees grow to a height of 4.5–9 m (15–30 ft) with a gnarled and stout trunk that reaches 0.3–0.9 m (0.98–2.95 ft) in diameter. The bark is smooth, slightly fissured, and covered in gray or black spines up to 1 cm (0.39 in) in length. The bark on the main trunk of mature trees has a distinct orange cast, [2] which is caused by a terrestrial alga. [3]
The wiliwili is summer (dry season) drought deciduous. The dry season usually begins in late April or in May, and trees in the wild typically lose all of their leaves before they bloom. [4] Trees in cultivation may retain much of their foliage through blooming time. [5] The flowers appear in the first half of the dry season, from April through July. [2] They form on horizontal or nearly horizontal racemes that are 7.5–15 cm (3.0–5.9 in) long. The flower color may be orange, yellow, salmon, greenish or whitish. [2] Sometimes all of these colors occur in a single population. The standard petal is erect, not enclosing the other petals. Like all of the erythrinas, the wiliwili is pollinated by birds. [6] The horizontal raceme and the erect standard are adaptations to pollination by passerine birds. [7] Many other erythrinas are pollinated by hummingbirds, which do not occur in Hawaii.
Pods develop and persist on the tree, with the seeds remaining attached long after the pods have opened. The seeds are dislodged by heavy downpours that generally start around November in the islands. Many seeds germinate quickly, and a well-established seedling can grow to 4 ft (1.2 m) in height before the start of the next dry season.
That the wiliwili bears spines is unusual for a species that has evolved in the isolated Hawaiian Islands, without the presence of ungulates or other large herbivores. Many plants in the islands have consequently evolved away the protection of spines. The wiliwili is thought to be closely related to E. tahitensis, a tree endemic to the Tahitian Archipelago, and E. velutina, a widespread species found in tropical South America and the Caribbean. [4]
Wiliwili is occasionally seen in cultivation in Hawaiʻi. It is easily propagated from cuttings. [8] Seven other species of Erythrina were under general cultivation in the Hawaiian Islands, but have been mostly extirpated by the alien gall wasp (see Conservation, below). [5] They were popular street trees in dry areas and windbreaks on fields. At least 80 others have been known in botanical gardens there. [9] No non-native species of Erythrina is known to be naturalized in Hawaiʻi. [4]
The wiliwili is distinguished from the other seven cultivated species by a pod with only one to three red or yellow-orange seeds, which sink in water; [10] non-native Erythrina have pods with larger numbers of brown seeds, which float in water. [11]
Native Hawaiians made a number of items from wiliwili wood because of its low density, such as mouo (fishing net floats), ama (outrigger canoe floats, [12] and extremely long papa heʻe nalu (surfboards) called olo. Olo, which averaged 18 feet (5.5 m), were exclusively ridden by aliʻi (royalty). [13] The wood was sometimes used for the waʻa (hull) of outrigger canoes intended to be used near-shore, for recreation, or for training. [14] The shiny orange-red seeds were strung into lei . [2]
Like many other native species in Hawaiʻi, the wiliwili is threatened by competition with non-native species that are free of the diseases, parasites, and herbivores that constrain them in their original habitats.
It was additionally reported in December 2005 [15] that the Hawaiian wiliwili population was under immediate threat due to an infestation by a gall wasp, [16] Quadrastichus erythrinae , which had been first reported in Hawaiʻi in April of that year. This invasive species appears to have arrived in Hawaiʻi via southern Taiwan, Singapore and southern China within only two years. This species was not previously known to science and was formally named and described in 2004. [17] It is thought to have originated in Africa, and the means of its rapid dispersal across South Asia, the Pacific, and southern North America is not understood. [18] The majority of trees of introduced Erythrina species have died as a result of gall wasp infestation. Native wiliwili forests have also been hard hit, particularly Puʻu o Kali on the island of Maui - prior to 2001, the best remaining example of a Hawai'i low elevation dryland forest ecosystem. The USGS-Pacific Island Ecosystems Research Center study site now documents the destructive impact of two invasive insect species (African bruchid beetle Specularius impressithorax and erythrina gall wasp) on Erythrina sandwicensis. [19]
A parasitoid wasp, Eurytoma erythrinae, was released by the Hawaiʻi Department of Agriculture in December 2008 as a biocontrol to minimize the damaging effects of Quadrastichus. Eurytoma wasps lay their eggs in the galls created by Quadrastichus wasps. Eurytoma larvae hatch faster than Quadrastichus larvae, on which they exclusively feed. [20] The introduction of Eurytoma has reduced the population of Quadrastichus to a point where the wiliwili trees no longer die, but still have a much reduced production of viable seeds. That's largely because Eurytoma larvae need to feed on multiple Quadrastichus to complete their development, and egg-laying female Eurytoma therefore ignore small isolated galls containing a single larva. The Hawaii Departments of Agriculture and of Land & Natural Resources therefore plan to introduce a second parasitoid wasp from Africa, Aprostocetus nitens. The smaller A. nityens completes its development feeding from a single Quadrastichus larva, and it is therefore expected to complement Eurytoma by targeting isolated larvae. [21]
The genus Erythrina was established by Linnaeus in 1753 in his book, Species Plantarum . [22] The name means "red", a reference to the flower color of some of the well-known species.
In 1786, in his book Encyclopédie Méthodique: Botanique , Jean-Baptiste Lamarck originated the name Erythrina monosperma for a Leguminous tree from India and Southeast Asia. [23] That tree has been known as Butea monosperma ever since William Roxburgh created the genus Butea in 1795.
Unaware of Lamarck's name, Charles Gaudichaud-Beaupré created the name Erythrina monosperma for the Hawaiian Erythrina in 1830 in his book Voyage of the Uranus. [24]
In 1841, William Jackson Hooker and George Arnott used Gaudichaud's name in their book, The Botany of Captain Beechey's Voyage. [25]
Gaudichaud's name, Erythrina monosperma, was used by most of those who described the Hawaiian species of Erythrina throughout the nineteenth century, including William Hillebrand. [26]
In 1932, Otto Degener created the name Erythrina sandwicensis to replace Erythrina monosperma. [8] He stated no reason for the name change. He presented a more complete synonymy than the one given here. Erythrina sandwicensis is the name that has been used since 1932.
Erythrina is a genus of plants in the pea family, Fabaceae. It contains about 130 species, which are distributed in tropical and subtropical regions worldwide. They are trees, with the larger species growing up to 30 m (98 ft) in height. The generic name is derived from the Greek word ερυθρóς erythros, meaning "red", referring to the flower color of certain species.
Acacia koa, commonly known as koa, is a species of flowering tree in the family Fabaceae. It is endemic to the Hawaiian Islands, where it is the second most common tree. The highest populations are on Hawaiʻi, Maui and Oʻahu.
Charles Gaudichaud-Beaupré was a French botanist.
Hibiscus tiliaceus, commonly known as the sea hibiscus or coast cottonwood, is a species of flowering tree in the mallow family, Malvaceae, with a pantropical distribution along coastlines. It has also been introduced to Florida and New Zealand. It has been debated whether this species is native or introduced to Hawaii.
The Hawaiian tropical rainforests are a tropical moist broadleaf forest ecoregion in the Hawaiian Islands. They cover an area of 6,700 km2 (2,600 sq mi) in the windward lowlands and montane regions of the islands. Coastal mesic forests are found at elevations from sea level to 300 m (980 ft). Mixed mesic forests occur at elevations of 750 to 1,250 m, while wet forests are found from 1,250 to 1,700 m. Moist bogs and shrublands exist on montane plateaus and depressions. For the 28 million years of existence of the Hawaiian Islands, they have been isolated from the rest of the world by vast stretches of the Pacific Ocean, and this isolation has resulted in the evolution of an incredible diversity of endemic species, including fungi, mosses, snails, birds, and other wildlife. In the lush, moist forests high in the mountains, trees are draped with vines, orchids, ferns, and mosses. This ecoregion includes one of the world's wettest places, the slopes of Mount Waiʻaleʻale, which average 373 in (9,500 mm) of rainfall per year.
Butea is a genus of flowering plants belonging to the pea family, Fabaceae. It includes five species native to the Indian Subcontinent, Indochina, Tibet, and southern China. It is sometimes considered to have only two species, B. monosperma and B. superba, or is expanded to include four or five.
Charpentiera is a flowering plant genus in the family Amaranthaceae. It consists of five species endemic to Hawaiʻi, where they are known as pāpala, and one species found only on the island of Tubuai in the Austral Islands. All species are trees, some reaching more than 10 metres (33 ft) in height. The genus is named for Arsène Charpentier (1781-1818), professor of pharmacy at Antwerp from 1810 to 1814 and at Cherbourg from 1814 to 1816.
Polyscias racemosa, or false 'ohe, is a species of flowering plant in the family Araliaceae. As Munroidendron racemosum, the species was until recently considered to be the only species in the monotypic genus Munroidendron. With the change in classification, Munroidendron is now obsolete. Polyscias racemosa is endemic to the Hawaiian island of Kauai. It is very rare in the wild and some of its original habitat has been replaced by sugar cane plantations. It was thought for some time to be probably extinct, but was rediscovered a few years prior to 1967.
Kokia drynarioides, commonly known as Hawaiian tree cotton, is a species of flowering plant in the mallow family, Malvaceae, that is endemic to the Big Island of Hawaii. It inhabits dry forests at elevations of 455–1,915 m (1,493–6,283 ft). Associated plants include ʻāheahea, ʻaʻaliʻi, hala pepe, wiliwili, uhiuhi, kōlea, ʻaiea, kuluʻī, ʻālaʻa, ʻohe kukuluāeʻo, māmane, and maua. It is threatened by habitat loss and competition with invasive species, such as fountain grass.
Urera is a genus of flowering plants in the nettle family, Urticaceae. It has a pantropical distribution.
Bobea is a genus of flowering plants in the family Rubiaceae. All species in this genus are endemic to Hawaii. Bobea was named for Jean-Baptiste Bobe-Moreau by Charles Gaudichaud-Beaupré in 1830 in his book Voyage de l'Uranie.
Euphorbia haeleeleana, the Kauaʻi spurge, is a species of flowering plant in the croton family, Euphorbiaceae, that is endemic to the islands of Kauaʻi and Oaʻhu in Hawaii. Like other Hawaiian spurges it is known as `akoko.
Nothocestrum breviflorum, commonly known as smallflower ʻaiea, is a species of tree in the nightshade family, Solanaceae, that is endemic to the island of Hawaiʻi. It inhabits dry and mixed mesic forests at elevations of 180–1,830 m (590–6,000 ft). These forests are dominated by ʻōhiʻa lehua and koa or lama, while plants associated with smallflower ʻaiea include wiliwili and uhiuhi. N. breviflorum reaches a height of 10–12 m (33–39 ft). It is threatened by habitat loss. It is federally listed as an endangered species of the United States. There are fewer than 50 individuals remaining.
Dracaena konaensis, synonym Pleomele hawaiiensis, the Hawaiʻi hala pepe, is a rare species of flowering plant that is endemic to the island of Hawaiʻi in the state of Hawaii.
Hawaiian tropical dry forests are a tropical dry broadleaf forest ecoregion in the Hawaiian Islands. They cover an area of 6,600 km2 (2,500 sq mi) on the leeward side of the main islands and the summits of Niʻihau and Kahoʻolawe. These forests are either seasonal or sclerophyllous. Annual rainfall is less than 127 cm (50 in) and may be as low as 25 cm (9.8 in). The rainy season there lasts from November to March.
Psydrax odorata, known as alaheʻe in Hawaiian, is a species of flowering shrub or small tree in the coffee family, Rubiaceae. It is native to the Pacific Islands, New Guinea and Australia.
Senna gaudichaudii, also known by many common names, including kolomana in Hawaii and as blunt-leaved senna in Australia, is a species of flowering plant in the family Fabaceae and is native to some Pacific Islands including Hawaii, parts of Southeast Asia and Queensland in Australia. It is shrub or small tree with pinnate leaves, usually with three to five pairs of oblong to egg-shaped leaflets, and yellow flowers arranged in groups of four to ten, with ten fertile stamens in each flower.
Hillebrandia sandwicensis is a species of a herbaceous perennial flowering plant native to some of the Hawaiian Islands. Common names include ʻakaʻakaʻawa and puʻa maka nui. The genus name honors the German physician William Hillebrand.
Phytolacca sandwicensis, also known as Hawai'i pokeweed, is a member of the Phytolaccaceae family and is a flowering and fruit bearing species endemic to the Hawaiian Islands, where it is found on Kauaʻi, Oʻahu, Molokaʻi, Maui, and Hawaiʻi. Locally it is referred to as pōpolo kū mai and/or pōpolo.Pōpolo itself is a term for any Solanum species, which its berries resemble.
Quadrastichus erythrinae Kim, 2004, is a small parasitoid wasp belonging to the family Eulophidae, but also a secondary phytophage by way of inducing galls on the leaves, stems, petioles and young shoots of various Erythrina species.
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