Hoya danumensis
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Hoya danumensis is a plant of the genus of wax flowers ( Hoya ) of the subfamily of asclepiadoideae (Asclepiadoideae) in the family of Hundsgiftgewächse (Apocynaceae).
features
Hoya danumensis is an epiphytic , climbing, slightly woody climbing plant. The cylindrical shoots wind z. T. counterclockwise. You are e.g. Some of them have fluffy hairs, other shoots are also glabrous, often even over long lengths without leaves. They grow upright or expand. Lignify older shoots. The leaves are opposite and petiolate. The leaf blades are elliptical-lanceolate, leathery and not succulent. They are 8 to 12 inches long and 3 to 5 inches wide. The base is obtuse-angled, the apex is sharp-pointed to tail. The central rib of the leaf blade is raised on the underside, the secondary ribs are less prominent. The 6 to 8 secondary leaf veins are at an angle of 60 to 80 ° to the midrib and split towards the leaf margin. The petioles are 3 to 5 mm long and 1 to 2.5 mm in diameter.
The umbel-shaped, hanging inflorescences arise individually at the nodes. One inflorescence contains up to 20 flowers, the surface is convex. The inflorescences hang down. The persistent, bare inflorescence stalks are 0.5 to 1.5 cm long. The rachis or stump shows the scars of earlier flower approaches. The flower stalks are bare and 2.5 to 4 cm long. The greenish sepals are lanceolate, slightly succulent and 1 to 1.5 wide at the base and 1.5 to 2 mm long. The apex is pointed, the outside is warty and sparsely hairy. The white to whitish-yellow, fleshy corolla is fused at the base and is bell-shaped. It has a diameter of 2.5 to 3.5 cm. The petal tips are bare and predominantly overgrown. The free part is about 0.8 to 1 mm long and 0.8 to 1 mm wide. The edges are bent over and the apex is pointed. On the underside of the corolla, between the sepals and near the base of the peduncle, there are distinct humps. The bumps are 4 to 4.5 mm long, 2 to 2.3 mm high and 1 to 1.2 mm wide. The star-shaped corolla is fleshy with ovoid-elongated lobes, 5.5 to 6 mm long and 2.4 to 2.6 mm wide. The inner, yellowish-green process is slightly concave, the outer process is flat and translucent white.
The Pollinia are elongated 550 to 570 µm with a width of about 200 to 210 µm. A caudicle (translator arm) is 150 to 190 µm long. The corpusculum is 210 to 230 µm long and 100 to 110 µm wide. Fruits and seeds are not yet known.
Similar Art
Hoya campanulata has a similar, bell-shaped flower, but on average it is slightly smaller. The lobes of the secondary crown are on average shorter (4.5 to 5.5 mm vs. 5.5 to 6) and narrower (max. 1.5 to 2 mm vs. 2.4 to 2.6 mm). In Hoya campanulata , the cusps on the underside of the corolla near the flower stalk are missing.
Geographical distribution and habitat
The nominate subspecies is so far only known from the Danum valley in Sabah (Borneo, Malaysia). The subspecies Hoya danumensis subsp. amarii is known from North Sumatra . The species occurs in moist primary forests as an epiphyte, usually on bushes and climbing on smaller trees at about 200 to 400 m above sea level.
Taxonomy
The original plant was collected in 1993 by Ted Green in the Danum Valley (Sabah, Borneo) and raised in Hawaii. The holotype and isotypes were taken from this cultivated plant in 2008. The holotype is kept in the herbarium of the Natural History Museum in Florence (herbarium abbreviation FI) under the number M. Rodda 2008.1h. Isotypes are in Kew Gardens (K), Naturalis in Leiden (L) and University of Turin (TO)
The plant was misidentified as Hoya campanulata flower (Green, 1994) by hobby plant collectors . Burton pictured the species under Hoya wallichii (Wight) CM Burton. However, this species differs from the new species by the corolla lobes. The plant that Ted Green collected was therefore described as a new species by Sri Rahayu and Michele Rodda. It is accepted as a valid taxon.
There are currently two subspecies:
- Hoya danumensis subsp. danumensis
- Hoya danumensis subsp. amarii S.Rahayu & Rodda (2019), North Sumatra, bell-shaped corolla is less deep, corners of the corolla are slightly shorter
literature
- Michele Rodda a & Torill Nyhuus: Hoya danumensis, a new species of Hoya (Apocynaceae, Asclepiadoideae) from Borneo. Webbia: Journal of Plant Taxonomy and Geography, 64 (2): 163-167, 2009 doi : 10.1080 / 00837792.2009.10670856
- Surisa Somadee and Jens Kühne: Hoya 200 different wax flowers. 96 p., Formosa-Verlag, Witten 2011 ISBN 978-3-934733-08-4 , p. 40.
Individual evidence
- ↑ Kew Science - Plants of the World online: Hoya danumensis Rodda & Nyhuus
- ^ International Plant Names Index
- ↑ Sri Rahayu, Michele Rodda: Hoya of Sumatra, an updated checklist, three new species, and a new subspecies. European Journal of Taxonomy 508: 1–23, 2019 ISSN 2118-9773 doi : 10.5852 / ejt.2019.508