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Euphorbia arnottiana

Endl. (1836)

This name is accepted

Kingdom: Viridiplantae Phylum: Magnoliophyta Class/Clade: Eudicot-Rosids Order: Malpighiales Family: Euphorbiaceae Genus: Euphorbia

‘ākoko, ‘akoko [akoko], ‘ekoko [ekoko], koko, kōkōmālei [kokomalei]

Description

Key Characters:

Growth Form: Shrubs.

Stems: Stems erect to spreading, 0.5–1.5(–2) m long, branches slender, flexuous, glabrous.

Roots:

Leaves: Leaves simple. Opposite, distichous. Blades ovate to broadly lanceolate, 17–50 mm long, 10–30 mm wide. Apex acute to acuminate, sometimes retuse. Base rounded to obtuse, oblique. Surfaces glabrous. Margins serrate. Petioles 1.5–4 mm long, pilose above. Stipules triangular, 0.5–1 mm long, erose, ciliate.

Flowers: Flowers in cyathia in branched, cymose inflorescences or occasionally solitary in the leaf axils, peduncles 1–2(–3) mm long, glabrous. involucre campanulate, 1.5–2(–2.5) mm high, 1.5–2 mm wide, glabrous to pilose beneath the glands, glands 4, green. Flowers unisexual and highly reduced. Pistillate flowers solitary, on a gynophore; staminate flowers in 5 groups or cymules, each with 1 to several flowers. Calyx (sepals) absent. Corolla (petals) absent. Male flower reduced to a single stamen, with an articulation at junction of pedicel and filament, subtended by slender bracteoles. Ovary superior; styles white to pink, bifid almost ½ their length, 0.3–0.5 mm long; stigma thickened.

Fruit: Capsules green; 2–3 mm long; glabrous to villous along the sutures; glabrate at maturity; gynophores recurved; exserted 2–3 mm from involucre; pilose. Seeds white to brown; 1.5–1.7 mm long; transversely rugose.

Ploidy: 2n = ca. 38*

Habitat: Dry shrubland and mesic forest.

Elevation Range: 300–600 m.

Historical Distribution

Uses and Culture

USES

Natural History

Statewide Status

Endemic

Island Status

O'ahu Endemic

Dispersal Agents


Pollinators

Bibliography

Name Published In: Ann. Wiener Mus. Naturgesch. 1: 184 (1836)

Other References

Wagner et al. 1990:604 (O [as Chamaesyce arnottiana]); Govaerts et al. 2000:674/Yang & Berry 2011 (Syn. C. arnottiana = E. arnottiana)

Occurrences

SNo. Scientific Name Locality Habitat Basis of Record Recorded By Record Number Island Source Date
1 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Growing in rocky talus area below small ledge with Kadua acuminata, Carex meyenii, Carex wahuensis, Blechnum appendiculatum, Odontosoria chinensis, Asplenium musifolium, Psidium cattleianum, Schinus terebinthifolius, Heptaplurum actinophyllum, and others. Preserved_Specimen Thomas, M.K. 932 Oahu BISH 2024-12-26
2 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Growing in entisol (soil) on talus. Under closed canopy of Aleurites & Acacia, w/ Canthium, Diospyros, & Schinus subcanopy. Shrub layer dominated by Cordyline, and herb layer by Oplismenus. Preserved_Specimen Warshauer, F.R. 2140 Oahu BISH 1978-09-10
3 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Mesic summer-dry forest Preserved_Specimen Herbst, D.R. 5974 Oahu BISH 1977-10-30
4 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Under a canopy of Psidium. Preserved_Specimen Obata, J.K. 77318 Oahu BISH 1977-09-01
5 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details In opening forest among shrubs Preserved_Specimen Egler, F.E. 37202 Oahu BISH 1937-07-20
6 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details On steep banks. Preserved_Specimen Sohmer, S.H. 11951 Oahu BISH 1983-11-27
7 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Growing on slope in mesic forest with Diospyros sandwicensis, Planchonella sandwicensis, Psydrax odorata, Psidium cattleianum, Schinus terebinthifolius, Bidens sandvicensis, Asplenium musifolium, Odontosoria chinensis, Metrosideros polymorpha, Alyxia stellata, Leucobryum gracile, Pyrrhobryum spiniforme, etc. Preserved_Specimen Thomas, M.K. 1125 Oahu BISH 2025-01-24
8 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Lower forest, in shade in rich dry forest, Sideroxylon, Dracaena, Pittosporum, Eugenia rariflora, Ochrosia, Neraudia, etc. Preserved_Specimen Hatheway, W.H. 501 Oahu BISH 1950-12-19
9 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Gregarious understory on forested East slope Preserved_Specimen Degener, O. 21182 Oahu BISH 1950-12-19
10 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Preserved_Specimen Forbes, C.N. 1578 Oahu BISH 1910-04-12
11 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Growing on steep slope of ridge in mesic forest with Psidium cattleianum, Diospyros sandwicensis, D. hillebrandii, Carex wahuensis, Elaphoglossum aemulum, Oplismenus hirtellus, Eugenia reindwardtiana, Planchonella sandwicensis, Pittosporum flocculosum, Acacia koa, Schinus terebinthifolius, and others. Preserved_Specimen Thomas, M.K. 413 Oahu BISH 2022-06-25
12 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details On loamy slopes abore the streambed. Dominant local associates include: Diospyros ferrea subsp. sandwicensis, Hedyotis acuminata, and Blechnum occidentale. Preserved_Specimen Takeuchi, W.N. 1711 Oahu BISH 1986-08-26
13 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Common on open wooded slope Preserved_Specimen Degener, O. 8101 Oahu BISH 1932-06-04
14 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details In a clearing within a Cordyline colony, near Pittosporum. Preserved_Specimen Takeuchi, W.N. 2246 Oahu BISH 1985-06-16
15 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Under dense Aleurites canopy. Sp. achieves best performance on mesic slopes above the streambed, PRC 838. Preserved_Specimen Takeuchi, W.N. 1710 Oahu BISH 1984-08-26
16 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Disturbed mesic forest of Psidium cattleianum and Schinus terebinthifolius, with Myrsine lessertiana, Pittosporum glabrum, Psydrax odorata, Bidens sandwicensis, Ageratina riparia. Preserved_Specimen Imada, C. 200437 Oahu BISH 2004-04-23
17 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Under dense Aleurites canopy. Sp. achieves best performance on mesic slopes above the streambed, PRC 838. Preserved_Specimen Takeuchi, W.N. 1710 Oahu BISH 1984-08-26
18 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details On slopes of the ridge in mesic, summer-dry forest. Preserved_Specimen Herbst, D.R. 5974 Oahu BISH 1977-10-30
19 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Preserved_Specimen Forbes, C.N. 2528 Oahu BISH 1919-01-01
20 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Preserved_Specimen Forbes, C.N. 2463 Oahu BISH 1917-04-11
21 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Preserved_Specimen Mann, H. 103 Oahu BISH 1965-10-01
22 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Preserved_Specimen Forbes, C.N. 2503 Oahu BISH 1917-05-04
23 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Preserved_Specimen Kores, P.J. Oahu BISH 1981-07-01
24 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Preserved_Specimen Oahu BISH
25 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Preserved_Specimen Forbes, C.N. 1578 Oahu BISH 1910-04-12
26 Euphorbia arnottiana Locality redacted. Contact Bishop Museum Botany Department for details Preserved_Specimen Forbes, C.N. 2503 Oahu BISH 1917-05-04
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