Of the 441 known plant species native to the Ogasawara Islands, 161 species are recognized as endemic (IUCN, 2011).
What does endemism mean? Why does it matter?
37% endemism rate
mesic forests, dry forests, and scrub forests (see wwf)
441 documented taxa of native plants including 161 taxa of endemic vascular plants and 88 taxa of endemic woody plant, according to the ICUN's 2010 technical evaluation of the islands prior to their UNESCO certification
weird apocryphal story about iwo jima botany students in wwii
Please see below for brief introductions to 18 of the 161 plants endemic to the Ogasawara Islands. For further taxonomic exploration, please visit the websites embedded in each species' genus and family name.
What does endemism mean? Why does it matter?
37% endemism rate
mesic forests, dry forests, and scrub forests (see wwf)
441 documented taxa of native plants including 161 taxa of endemic vascular plants and 88 taxa of endemic woody plant, according to the ICUN's 2010 technical evaluation of the islands prior to their UNESCO certification
weird apocryphal story about iwo jima botany students in wwii
Please see below for brief introductions to 18 of the 161 plants endemic to the Ogasawara Islands. For further taxonomic exploration, please visit the websites embedded in each species' genus and family name.
Endemic Plant SpeciesSantalum boninense
Santalaceae Santalum boninense, a rare shrub species, has a narrow distribution across the Ogasawara Islands. The Japanese Ministry of Environment classifies the species as endangered. Santalum boninense grows in open space and produces white, bell-shaped flowers that measure 5-10 mm and bloom for less than two days. Insect visitors to the flowers include honeybees, moths and cockroaches (which have been observed primarily at night). Although Santalum boninense blooms are regularly visited by non-native honeybees, few flowers produce fruit. The species is currently found on Chichijma, Anijima, Hahajima and Imotojima. Machilus boninensis
Lauraceae Machilus boninensis, a common tree species, produces dish-shaped green flowers on the surface of the forest canopy. The small, insect-pollinated blooms measure 5-10 mm and last for less than two days. Observed insect visitors to the species' flowers include flies (pictured) and thirps. Machilus boninensis occurs on Mukojima, Nakodojima, Chichijima, Anijima, Ototojima, Hahajima, Mukohijima, Imotojima and Meijima. The Japanese Ministry of Environment classifies Machilus boninensis as a not-threatened species. Claoxylon centinarium
Euphorbiaceae Claoxylon centinarium, a rare, monoecious brush species, occurs in narrow distribution. Currently, Claoxylon centinarium is found only on the forest understory on Hajajima. The species, sometimes described as a tree, produces flowers less than 5 mm in size. These small flowers are primarily visited by flies but beetles and ants have also been observed. The Japanese Ministry of Environment classifies Claoxylon centinarium as a critically endangered species. Boninia glabra
Rutaceae Boninia glabra, a common dioecious tree species, is found in the forest understory on Mukojima, Nakodojima, Chichijuma, Anijima, Ototojima, Hahajima and Mukohijima. The Japanese Ministry of Environment does not consider Boninia glabra a threatened species. Trees produces a 5-10 mm dish-shaped white flower which blooms for 2-4 days. During daytime hours, honeybees, flies, beetles, ants and thirps have been oberserved visiting the insect-pollinated blooms blooms. Ants visitors have also been observed at night. Wikstroemia pseudoretusa
Thymelaeceae Wikstroemia pseudoretusa occurs on Mukojima, Chichijima, Ototojima and Hahajima. The Japanese Ministry of Environment classifies the species as endangered. Wikstoemia pseudoretusa produces small (5-10), tube-shaped yellow flowers that bloom for 4-6 days. Observed daytime insect visitors to the species' flowers include honeybees, ants and thirps. The species is of particular note for its evolution into dioecy (like Dendrocacalia Crepidofolia) on the Ogasawara Islands. See Makoto Kato and Hidetoshi Nagamasu, "Dioecy in the Endemic Genus Dendrocacalia (Compositae) on the Bonin (Ogasawara) Islands," Journal Plant Resources, 108: 443-450, 1995. Stachyurus praecox var. macrocarpus
Stachyuraceae (occurs as stachyurus praecox var. macrocarpus 1 and 2; differentiated into two species) 1 occurs on ch, ami, ot, ha 2 occurs only on ha endemic threatened; vulnerable common shrub dioecy open space tube yellow 4-6 days 5-10 mm 1–10 101-1000 insect honeybees, ants, thirps (observed, but none at night) highly endangered, pollinated by moths (pictured) Vaccinium boninense
Ericaceae occurs mk, ch, ami, ot, ha blueberry family endemic threatened; vulnerable common shrub hermaphrodite open space bell white 4-6 days 10-30 mm 11-100 101-1000 insect endemic bees, moths, ants, thirps; moths at night, but narrow mouth of the flower eliminates most of these insects as potential pollinators Myrsine maximowiczii
Myrsinaceae occurs as 1 and 2, differentiated into 2 species 1 occurs mk, nk, ch, ami, ot, ns, ha, mkh, ame, im, me, unidentified small outcroppings 2 occurs chi, ami, ha, im endemic threatened; vulnerable rare; wide distribution tree monoecy canopy surface dish white 4-6 days 5-10 mm 101-1000 101-1000 insect ants endemic woody (no flower pictured) Ligustrum micranthum
Oleaceae occurs mk, chi, ami, ot, ha, mkh, ame, im, me, unidentified small outcroppings endemic common shrub hermaphrodite canopy surface dish white <2 days 5-10 mm 101-1000 101-1000 insect honeybees, endemic bees, flies, ants, thirps---specialist = thirps pollinated by flies, though introduced honeybees (as shown) visit them Hedyotis grayi
Rubiaceae occurs mk, nk, ym, ch, ami, ot, ha, mkh, hr, ame, im, me, ki endemic threatened; vulnerable; occurs on all island groups 'introduced honeybees act as nectar robbers' Scutellaria longituba
Lamiaceae (Labiatae) occurs ch, ami skullcap endemic near threatened; low risk rare; wide distribution perennial herb hermaphrodite forest understory tube white 4-6 days >30 mm insect honeybees; observed at night but no visitors species has longer tube than other Scutellaria species, however no butterflies have been observed as pollinators Lobelia boninensis
Campanulaceae occurs mk, nk, kt, ch, hg, ha, mkn, hr, ame, im, me, endemic threatened; vulnerable rare; wide distribution perennial herb hermaphrodite open space zygomorphic white 2-4 days 10-30 mm insect xlocopa bees, endemic bees, other bees, flies, butterlies, ants only endemic campanulaceae plant Crepidiastrum grandicollum
Asteraceae occurs ch, ami endemic threatened; endangered rare; narrow distribution perennial herb hermaphrodite open space dish yellow 2-4 days <5 mm insect honeybees, ants visited by introduced honeybees Dendrocacalia crepidifolia
Asteraceae (Compositae) occurs mk, ha, mkh, im me endemic threatened; vulnerable rare; narrow distribution tree dioecy open space dish pink >6 days <5 mm instect honeybees, flies, butterflies See Makoto Kato and Hidetoshi Nagamasu, "Dioecy in the Endemic Genus Dendrocacalia (Compositae)on the Bonin (Ogasawara) Islands," Journal Plant Resources, 108: 443-450, 1995. Sciaphila okabeana
Triuridaceae occurs ch, ami, ot, ha, mkh, endemic threatened; vulnerable rare; narrow distribution annual monoecy forest understory dish violet 5-10 mm insect no observed visitors myco-heterotroph Alpinia boninensis
Zingiberaceae occurs ch, ha, ki one of three endemic gingers endemic threatened; endangered rare; narrow distribution perennial herb hermaphrodite forest understory zygomorphic white <2 days >30 mm insect xylocopa bees, flies, ants, grassphopper large white flowers, pollinated by Xylocopa ogasawarensis, an endemic bee Eulophia toyosimae
Orchidaceae occurs ch, ami, ot, ha, one of 17 endemic orchids (Zeuxine boninensis is classified as near extinct, occurring only on Hahajima) endemic rare; threatened; endangered wide distribution perennial herb hermaphrodite forest understory zygomorphic brown >6 days 10-30 mm insect beetles, ants; beetles and ants at night myco-heterotroph, like S. okabena Bulbophyllum boninensis
Orchidaceae occurs ch, ami, ot, ha endemic threatened; endangered rare; wide distribution perennial herb hermaphrodite forest understory zygomorphic yellow >30 mm insect observed but no visitors pollinated by a specialist moth and Xylocopa ogasawarensis |
References
Abe, Tetsuo; Katsuyuki Wada and Nobukazu Nakagoshi. 2008. “Extinction Threats of a Narrowly Endemic Shrub, Stachyurus macrocarpus (Stachyuraceae) in the Ogasawara Islands." Plant Ecology, Vol. 198, No. 2 (Oct., 2008), pp. 169-183. Abe, Tetsuo. 2006. Threatened Pollination Systems in Native Flora of the Ogasawara (Bonin) Islands.” Annals of Botany 98: 317–334.
Kaneko Shingo and Tetsuto Abe, Yuji Isagi. 2009. “Development of microsatellite markers for Stachyurus macrocarpus and Stachyurus macrocarpus var. prunifolius (Stachyuraceae), critically endangered shrub species endemic to the Bonin Islands.” Conservation Genetics 10(6):1865-1867.
Kato, M. and Hidetoshi N, "Dioecy in the Endemic Genus Dendrocacalia (Compositae) on the Bonin (Ogasawara) Islands," Journal Plant Resources, 108: 443-450, 1995.
Satoshi. 2007. “Species Richness Patterns along Environmental Gradients in Island Land Molluscan Fauna.” Ecology, Vol. 88, No. 7 (Jul., 2007), pp. 1738-1746
Tanaka, Nobuyuki; Keita Fukasawa; Kayo Otsu, Emi Noguchi; Fumito Koike. 2010. “Eradication of the Invasive Tree Species Bischofia javanica and Restoration of Native Forests on the Ogasawara Islands.” Restoring the Oceanic Island Ecosystem eds. Kazuto Kawakami and Isamu Okochi. 2010, 161171.
Tyner, Colin. 2011. “Disciplining Complex Natures in the Ogasawara Islands” Ph.D candidate, UCSC Department of History presentation.
Yoshida, Keiichiro and Shuichi Oka. 2004. “Invasion of Leucaena leucocephala and Its Effects on the Native Plant Community in the Ogasawara (Bonin) Islands," Weed Technology, Vol. 18, Invasive Weed Symposium (2004), pp. 1371-1375
Abe, Tetsuo; Katsuyuki Wada and Nobukazu Nakagoshi. 2008. “Extinction Threats of a Narrowly Endemic Shrub, Stachyurus macrocarpus (Stachyuraceae) in the Ogasawara Islands." Plant Ecology, Vol. 198, No. 2 (Oct., 2008), pp. 169-183. Abe, Tetsuo. 2006. Threatened Pollination Systems in Native Flora of the Ogasawara (Bonin) Islands.” Annals of Botany 98: 317–334.
Kaneko Shingo and Tetsuto Abe, Yuji Isagi. 2009. “Development of microsatellite markers for Stachyurus macrocarpus and Stachyurus macrocarpus var. prunifolius (Stachyuraceae), critically endangered shrub species endemic to the Bonin Islands.” Conservation Genetics 10(6):1865-1867.
Kato, M. and Hidetoshi N, "Dioecy in the Endemic Genus Dendrocacalia (Compositae) on the Bonin (Ogasawara) Islands," Journal Plant Resources, 108: 443-450, 1995.
Satoshi. 2007. “Species Richness Patterns along Environmental Gradients in Island Land Molluscan Fauna.” Ecology, Vol. 88, No. 7 (Jul., 2007), pp. 1738-1746
Tanaka, Nobuyuki; Keita Fukasawa; Kayo Otsu, Emi Noguchi; Fumito Koike. 2010. “Eradication of the Invasive Tree Species Bischofia javanica and Restoration of Native Forests on the Ogasawara Islands.” Restoring the Oceanic Island Ecosystem eds. Kazuto Kawakami and Isamu Okochi. 2010, 161171.
Tyner, Colin. 2011. “Disciplining Complex Natures in the Ogasawara Islands” Ph.D candidate, UCSC Department of History presentation.
Yoshida, Keiichiro and Shuichi Oka. 2004. “Invasion of Leucaena leucocephala and Its Effects on the Native Plant Community in the Ogasawara (Bonin) Islands," Weed Technology, Vol. 18, Invasive Weed Symposium (2004), pp. 1371-1375
images of species (c) Tetsuo Abe, 2006