Oparanthus

Oparanthus
Inflorescences of Oparanthus hivoanus
Systematics
Euasterids II Order : Astern-like (Asterales) Family : Daisy family (Asteraceae) Subfamily : Asteroideae Tribe : Coreopsideae Genre : Oparanthus
Scientific name
Oparanthus
Sherff

Oparanthus is a genus within the family of the daisy family (Asteraceae). The six or so species occur on someislands belongingto French Polynesia in the southern Pacific .

description

Vegetative characteristics

The Oparanthus species grow as shrubs or small trees that can reach heights of up to 12 meters. At least the wood of the young trunks is fibrous.

The cross-opposite leaves on the branches are divided into a petiole and a leaf blade. The petioles are slightly folded lengthways and their base encompasses the branch. The thin to relatively thick leaf blades are simple.

Inflorescences and flowers

All Oparanthus species are functionally monoecious, separate sexes ( monoecious ). The terminal, first upright and later pendulous, zymic total inflorescences usually consist of three, more rarely one or two cup-shaped partial inflorescences. The furrowed, angular and flattened inflorescence shafts are lignified. In the bell-shaped involucre , the leathery bracts are arranged in an irregular or two to three tiered rows . There are leathery bracts on the convex base of the cup.

The functionally unisexual flowers are four or five-fold with a double flower envelope . The flower heads include a plurality of functionally female florets (= ray florets) and functional male florets (= disc florets). The white or yellow elongated petals of the ray florets end in three, more rarely in two or four corolla lobes or teeth. The four-fold tubular flowers have white or yellow petals. The black anthers are linearly shaped and have a triangular tip. The functional stigma of the ray florets has two branches and is bent back. The stigma of the tubular flowers is linear or slightly club-shaped, two-branched and not functional. The sterile ovules are reduced in the tubular flowers. In the tubular flowers the black anthers are linear with a somewhat arrow-shaped base and triangular top.

Fruits and seeds

The woody, fertile achenes that form in the ray-flowers are elliptical to almost elliptical in shape and have one or two narrow wings. The wing extends over the tip of the achenes and forms a strong, short to elongated awn . The ribs on the surface occasionally continue as linear awns. The linearly shaped achenes that form in the tubular flowers are sterile and white one or two linear awns that fall off easily.

Occurrence

The natural range of the Oparanthus species is on some islands of French Polynesia in the southern Pacific . It includes there the Marquesas Islands and the Austral Islands belonging island Rapa Iti .

All species grow in moderately moist to moist forests. Two species are also found in windy locations in the cloud zone.

Systematics

Branch with opposite leaves and inflorescences of Oparanthus teikiteetinii

The genus Oparanthus was established in 1937 by Earl Edward Sherff in Occasional Papers of Bernice Pauahi Bishop Museum of Polynesian Ethnology and Natural History .

The genus Oparanthus belongs to the tribe Coreopsideae in the subfamily Asteroideae within the family of Compositae (Asteraceae or Compositae).

The genus Oparanthus contains six species in two sections since 2011:

• The four species of Oparanthus sect. Albiflori R.K. Shannon & WLWagner are native to the Marquesas Islands:
  • Oparanthus hivoanus (O.Deg. & Sherff) RKShannon & WLWagner
  • Oparanthus teikiteetinii (J.Florence & Stuessy) RKShannon & WLWagner
  • Oparanthus tiva W.L.Wagner & Lorence
  • Oparanthus woodii W.L.Wagner & Lorence

• The two kinds of Oparanthus sect. Oparanthus are endemic to Rapa Iti Island :
  • Oparanthus coriaceus (F.Br.) Sherff
  • Oparanthus rapensis (F.Br.) Sherff

swell

• Oparanthus. In: Flora of the Marquesas Islands. www.botany.si.edu/pacificislandbiodiversity/marquesasflora, accessed on December 24, 2016 (English). 

Individual evidence

1. ↑ ^{a b c d e f g h} Oparanthus. In: Flora of the Marquesas Islands. www.botany.si.edu/pacificislandbiodiversity/marquesasflora, accessed on December 24, 2016 (English). 
2. ↑ Oparanthus at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed December 24, 2016.
3. ↑ ^{a b c d} Warren L. Wagner, David H. Lorence: Two new Marquesan species of the southeastern Polynesian genus Oparanthus (Asteraceae, Coreopsidinae) . In: PhytoKeys . No. 4 , 2011, ISSN  1314-2003 , p. 129-148 , doi : 10.3897 / phytokeys.4.1603 .
4. ↑ ^{a b c d} Robynn K. Shannon, Warren L. Wagner: Oparanthus (Asteraceae, Subtribe Coreopsidinae) Revisited . In: Allertonia . tape 7 , no. 4 , 1997, ISSN  0735-8032 , p. 273-295 .

Web links

Commons : Oparanthus  - collection of images, videos and audio files

• Oparanthus on the IUCN Red List of Threatened Species1998. Retrieved December 25, 2016.