Hoya acicularis

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Hoya acicularis
Systematics
Order : Enzianartige (Gentianales)
Family : Dog poison family (Apocynaceae)
Subfamily : Silk plants (Asclepiadoideae)
Tribe : Marsdenieae
Genre : Wax flowers ( hoya )
Type : Hoya acicularis
Scientific name
Hoya acicularis
T. Green & Kloppenb.

Hoya acicularis is a plant of the genus of wax flowers ( Hoya ) of the subfamily of asclepiadoideae (Asclepiadoideae).

features

Hoya acicularis is an epiphytic , little climbing, also creeping plant, with slender, little branched, bare shoots . With larger plants, some shoots can also hang down. The opposite leaves are stalked, the petioles are curved and 7 to 10 mm long. The roughly round, almost needle-shaped, stiff leaf blades are 8 to 12 cm long, with a width (or thickness) 5 to 7 mm. They can be stretched, curved, or twisted. They are dark green, often with purple spots on the underside.

The umbel-shaped , hanging inflorescences arise from the leaf axils . They are multi-flowered (10 to 15 single flowers) and have a flat end. The diameter of the umbel is 3 to 4 cm. The persistent inflorescence stalks arise from the nodes and are up to 1.3 to 2 cm long.

The cream-colored, inside red corollas have a diameter of 6 to 7 mm. The petals are very strongly bent back and give the flower a button-like appearance. When the petal lobes are spread out, the corollas are 1.2 cm in diameter. The smooth and bare flower stalks are over 1.5 cm long and round in cross section, the length increases from the center to the periphery of the umbel. The outer flower stalks arise from the inflorescence stem at right angles and are bent by 90 °. The sepals are oblong-triangular, 1.7 mm long and 1.2 mm wide at the base, granular outside with a few hairs, glabrous on the inside. The elongated triangular petals are almost one third fused ( sympetalie ). The petal lobes measure at the base 2 mm in width, and 4.5 mm in length, the apices are pointed. They are bald on the outside, inside they are covered with white downy hairs, with the exception of the apices. The corolla is red on the inside and lighter on the outside. The outside is pink and bare. The tips of the secondary crown are bare and stand upright. The outer, ascending, cream-colored process ends bluntly and bilobate, the inner ascending process is narrow spatulate, with a cream-colored base and pink-colored apices. The surface of the tip is approximately flat with a light, central keel.

The Pollinia are 740 µm long and approximately the same 190 µm wide. The top and bottom are rounded uniformly. The caudiculae (or translator arms) are 220 µm long and protrude above the lower ends of the pollinia. The maximum width is about 130 µm. The pollinia sit with the lower, rounded end in the upper, somewhat lighter and funnel-shaped part of the caudiculae (or translator arms). The caudiculae start below the middle of the retinaculum (also known as the corpusculum ). The retinaculum is 150 µm long, the shoulders 50 µm wide, the "waist" 30 µm and the "hip" 50 µm wide.

Similar species

Hoya acicularis is similar to Hoya gigantanganensis Kloppenb., But the leaves of Hoya acicularis are semi-round and the stems of the inflorescences are much shorter at 1.5 cm. The authors also emphasize the unique shape of the Pollinia ("unique"). This is no longer the case, because the Hoya danumensis , also from Sabah, published in 2013 , has similar pollinia in general, but the dimensions and proportions are somewhat different. Hoya danumensis also has a completely different flower morphology.

Geographical distribution and habitat

The species occurs in the Malaysian state of Sabah and in Brunei (island of Borneo ). It grows there on trees in the lowland and mountainous rainforests as well as in ultramafic mountainous highland rainforests.

Taxonomy

The taxon was described in 2002 by Ted Green (bot. Abbreviation: T. Green ) and Robert Dale Kloppenburg (bot. Abbreviation Kloppenb. ). The holotype was collected by Ted Green on January 24, 1991 in the Danum Valley in Sabah, Malaysia. It is kept in the Herbarium Pacificum Bishop Museum (BISH) under the number BISH1000875. (In the original publication the collection number of the holotype is given as BISH 93031) The species name is derived from the needle-shaped leaves (Latin acicularis = needle-shaped). The species is accepted as a valid species by the Plants of the World database.

According to the phylogenetic analysis by Wanntorp et al. (2014) Hoya acicularis is the sister species of Hoya kloppenburgii . This small monyphylum forms with Hoya cf. tsangii and a small monophylum consisting of Hoya burtoniae and Hoya leytensis a previously unresolved trichotomy . Hoya acicularis belongs to clade V with 30 other taxa. Clade V consists of species that are native to the tropical Indomalaya and Australasia .

literature

Individual evidence

  1. ^ LE Newton: Terminology of Structures Associated with Pollinia of the Asclepiadaceae. Taxon, 33 (4): 619-621, 1984 JSTOR
  2. ↑ Holotype of Hoya acicularis at JSTOR Global Plants
  3. ↑ Kew Science - Plants of the World online: Hoya acicularis T. Green & Kloppenb.
  4. ↑ Livia Wanntorp, M. Grudinski, PI Forster, Alexandra N. Muellner-Riehl, GW Grimm: Wax plants (Hoya, Apocynaceae) evolution: Epiphytism drives successful radiation. Taxon 63: 89-102, 2014 doi : 10.12705 / 631.3

Web links

annotation

  1. ↑ The information on the diameter of the flowers is contradictory in the original publication. On page 8 (above) the diameter is given as 1.5 to 2 cm (“... bearing 1.5 - 2.0 cm beige flowers ...”), on p. 9 (below) the diameter is given as 1 , 2 cm indicated (“flower flattened is 1.20 cm in diameter”).
  2. ↑ The description of the corolla lobes is contradictory in the original description. On p. 10 it says: "scale does not reach the corolla sinus", while in the description of the figure above it says: "the scales exceed the corolla sinus". However, the figure clearly shows that the corolla lobes protrude clearly into the sinus formed by the corolla lobes.
  3. ↑ In the original work the terminology of Pollinaria is used incorrectly. Translator arms and caudiculae are synonyms (cf. Newton, 1990).