Oparanthus rapensis
| Oparanthus rapensis | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Oparanthus rapensis | ||||||||||||
| ( F.Br. ) Sherff |
Oparanthus rapensis is a species within the family of the daisy family (Asteraceae). It is endemic tothe island of Rapa Iti in the southern Pacific .
description
Vegetative characteristics
Oparanthus rapensis grows as a shrub or tree that can reach heights of up to 8 meters and trunk diameters of up to 0.2 meters. The grayish brown bark is smooth. The soft wood is cream-colored.
The cross-opposite leaves on the branches are divided into a petiole and a leaf blade. The petiole is 2 to 10 inches long. The simple, leathery leaf blade is 3.5 to 14 centimeters long and 3.5 to 16 centimeters wide, ovoid to approximately circular, occasionally elliptical to broadly elliptical, rarely also broadly inverted-ovoid. Occasionally, the leaf blades can split along the leaf median nerve. The base of the blade is blunt, wedge-shaped, slightly heart-shaped or unevenly, the tip of the blade is pointed or blunt, edged or prickly, the slightly thickened edge of the blade is whole or slightly toothed. Several pairs of conspicuous lateral nerves branch off from each side of the leaf central nerve and the higher-order leaf veins form a conspicuous, net-like pattern.
Inflorescences and flowers
Oparanthus rapensis is single sexed ( monoecious ) and the known flowering period extends from October to February. The terminal, at first upright and later hanging, zymic total inflorescences consist of three, cup-shaped partial inflorescences. The partial inflorescences are 0.5 to 0.6 centimeters in size and 0.3 to 0.6 centimeters in diameter. The inflorescence stem, if present, is 0.1 to 2 centimeters long. In the bell-shaped involucre , the six to ten bracts are arranged in an irregularly graduated row , which are 0.3 to 0.5 centimeters long. The bracts on the convex cup base are 0.3 to 0.4 centimeters long.
The functionally unisexual flowers are four-fold with a double flower envelope . The flower heads contain ten to twelve functional female florets (= ray florets) in a stepped up two rows and 8 to 20 functionally male florets (= disc florets). The petals of the ray florets are divided into an approximately 0.2 centimeter long corolla tube and an approximately 0.18 centimeter long tongue, which is deeply triple lobed at its tip. The tubular flowers have a corolla tube 0.18 to 0.2 centimeters long and corolla lobes 0.14 to 0.16 centimeters long.
Fruits and seeds
The fertile achenes , which form in the ray-flowers, are roughly elliptical to elliptical in shape with a length of 0.38 to 0.45 centimeters and have two wings. The 0.02 to 0.06 centimeter wide wings have a ciliate border, reach over the tip of the achenes and form an awn . The about 0.5 centimeter long achenes which form in the tubular flowers are sterile and white one or two awns, which can be up to 0.15 centimeters long.
Occurrence
The natural range of Oparanthus rapensis is on the island of Rapa Iti, which belongs to the Austral Islands .
Oparanthus rapensis thrives at altitudes of 50 to 350 meters. The species grows there in moderately moist to moist forests, mostly on slopes, more rarely on rock faces. Various types of Eurya , Freycinetia and ironwoods ( Metrosideros ) grow in these forests .
Systematics
It was first described as Chrysogonum rapense in 1935 by Forest Buffen Harkness Brown in Bulletin of the Bernice P. Bishop Museum. Honolulu . In 1937 Earl Edward Sherff transferred the species as Oparanthus rapensis in Occasional Papers of Bernice Pauahi Bishop Museum of Polynesian Ethnology and Natural History to the genus Oparanthus . A synonym for Oparanthus rapensis (F.Br.) Sherff is Bidens rapensis (F.Br.) Stuessy .
The species forms hybrids with Oparanthus coriaceus .
swell
- Robynn K. Shannon, Warren L. Wagner: Oparanthus (Asteraceae, Subtribe Coreopsidinae) Revisited . In: Allertonia . tape 7 , no. 4 , 1997, ISSN 0735-8032 , p. 273-295 .