Hoya sumatrana
| Hoya sumatrana | ||||||||||||
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Inflorescence, A = buds, B = plan view of the inflorescence, C = plan view of a single flower, D = underside of the flower with the folded tips, E = side view with the long membranous appendages, F = corolla corolla underside, F = pedicel with sepals and Ovarium, G = pollinarium |
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| Scientific name | ||||||||||||
| Hoya sumatrana | ||||||||||||
| S.Rahayu & Rodda |
Hoya sumatrana is a plant of the genus of wax flowers ( Hoya ) of the subfamily of asclepiadoideae (Asclepiadoideae).
features
Hoya sumatrana is an epiphytic , climbing plant. The shoots are 2 to 4 mm in diameter. Fresh shoots are pale green and hairy, older shoots are gray and glabrous. The internodes are 2 to 5 cm (rarely up to 10 cm) long. Adhesive roots are formed under the leaf nodes and along the internodes. The leaves are stalked, the petioles are 10 to 20 mm long and 3 to 6 mm in diameter. They are round in cross section, dark brown and freshly sparsely hairy, later bald. The leaf blades are elongated, egg-shaped or elliptical and 3 to 7 cm long (rarely up to 15 cm) and 3.5 to 5.5 cm wide. They are stiff and succulent, the base is rounded to pointed, the apex is pointed. The top is green with sparse gray spots, the underside pale green. When fresh they are sparsely hairy, with increasing age they become bald. At the base of each leaf is an approximately 1 × 1.5 mm wide, triangular, light brown gland. The leaf veins are pinnate but not protruding. All vegetative parts secrete a white milky juice when injured.
The umbel-shaped inflorescence has a diameter of 2.5 to 3 cm and contains 10 to 15 flowers. The surface is flat and it hangs down. The inflorescence stalks are 15 to 35 mm long and 1.5 to 2 mm thick. They arise individually from the leaf axils and persist for a long time. They are round in cross section, dark red in color and sparsely hairy. The flower stalks, which are round in cross-section, are 5 to 15 mm with a diameter of 0.7 to 1 mm. They are sparsely papillae, dark red at the base, and turn into a pale pink calyx. The sepals are narrow-triangular, 1.4 to 2 long and 0.5 to 0.8 mm wide, and are about 0.6 to 0.8 mm apart. The apex is rounded. They are papillary on the outside and bare on the inside. The corolla has a diameter of 7 to 9 mm when spread out. The corolla tube is very short, only about 1.5 mm high, cream-colored. It is densely hairy on the inside and bald on the outside. The petal lobes are triangular with back bent edges and very dead bent tips. They are 5 to 6 long and 2 to 3 mm wide at the base. Outside they are bald, inside predominantly very densely hairy and downy. Only the bent tip, approx. 1.5 mm, is bare. long. The staminal secondary crown is 2 to 2.5 mm high and 2.8 to 3.2 mm in diameter. The corolla lobes are colored red, 2.2 mm long and 0.8 mm wide. They are attached to the back of the dust bag at an angle of about 60 °. They are egg-shaped and slightly angled on top. The inner extension is split, the outer extension is rounded with a narrow fold at the base. The 0.5 × 0.4 mm measuring anthers are egg-shaped with a linear, apically rounded, membranous process that is 2.8 mm long. The pollinia are elongated, 280 to 320 μm long, 100 to 120 μm wide with a round base and an inwardly sloping apex. They have a transparent edge over the entire length. The almost transparent caudiculae are 100 to 120 μm long, with a diameter of 70 μm. The elongated corpusculum is 90 to 110 μm high and 40 to 60 μm high. The stylus head is pentagonal in cross section with five appendages that alternate with the stamens. The stylus head is conical at the top with a central point. It is 0.8 to 0.9 mm high and 0.4 to 0.5 mm wide at the base. Fruits and seeds were not observed.
Similar species
Hoya sumatrana was placed in the Hoya section Peltostemma Schlechter (1916) by the authors . This section is characterized by upright corolla lobes, long, linear anthers appendages that extend far over the stylus head and characterized by pollinaria with well-developed caudicle wings. The section currently includes six species. Hoya sumatrana can be distinguished from all other species in the section by its much smaller flowers. In addition, the inner secondary crown process is split, while it is pointed or rounded in all other species.
Geographical distribution and habitat
Hoya sumatrana is only known from the type locality in the province of Lampung , Sumatra , Indonesia. It grows there epiphytically in a coastal swamp forest.
Taxonomy
The taxon was first described by Sri Rahayu and Michele Rodda in 2019. The holotype is kept in the Research Center for Biology in Cibinong , Indonesia (S.ahayu 861 leg.). An isotype is also kept in the Singapore Botanic Gardens in Singapore . The species was named after the island of Sumatra.
literature
- 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