Hoya ruthiae
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Hoya ruthiae is a plant of the genus of wax flowers ( Hoya ) of the subfamily of asclepiadoideae (Asclepiadoideae).
features
Hoya ruthiae is a comparatively graceful, lithophytic climbing plant. The bare shoots measure up to 4 mm in cross-section, are customary or gray with a membranous, peeling bark. The internodes are 5 to 15 cm long. The fleshy leaves are stalked, the petioles are 5 to 15 mm long and 1.5 to 3 mm thick. The leaf blades are lanceolate 5 to 15 cm long and 1.5 to 3 cm wide. The apex is pointed, the base wedge-shaped. The top is light green, in direct sunlight the color changes to red with numerous gray spots, the underside is a little lighter green. Only the midrib is clearly visible, the secondary veins are hardly recognizable. All vegetative parts of the plant give off a clear milky sap when injured .
The umbel-shaped to spherical inflorescences contain 4 to 20 flowers and measure 3 to 4 cm in diameter. The bare inflorescence stalks arise from the leaf axils and are persistent. They are 1 to 3 cm long and 1.5 to 2.5 mm in diameter. The bare flower stalks are 10 to 15 mm long and 0.5 to 0.8 mm in diameter. The buds are cone-shaped with a pentagonal base, about 10 × 6 mm in size. The sepals are triangular, whitish-pinkish with a round apex. They are glabrous, 1.3 to 1.5 mm long and 0.7 to 1 mm wide at the base. An egg-shaped gland sits at the base of each sepal. The wheel-shaped corolla has a diameter of 1 to 1.5 cm, or 1.8 to 2.2 cm when spread out. It is white with a pink tint, thinly and very finely hairy on the inside, bald on the outside. The corolla tube is 1.5 to 2 mm long. The petals are only fused at the base. They are narrowly lanceolate with a triangular pointed apex, 9 to 10 mm long and 3 to 4 mm wide at the base. The edges are rolled up, the tips of the petal lobes are rolled up. The gynostegium is pedunculated, the stem is conical 1 to 1.2 mm high and approx. 2 mm in diameter. The staminal side crown is 2.5 to 3 mm high and measures 6 to 7 mm in diameter. It is fleshy, yellowish in color and has a purple center. The corolla lobes are laterally narrowed, egg-shaped from above with rolled edges. They measure 2.8 to 3.2 mm in length and 1 to 1.2 mm in width. The inner process is erect, as high as the anthers, and linear in shape with a pointed apex, the outer process is rounded. The anthers are ovoid, 650 to 750 μm long and 300 to 400 μm wide, with an apically round, membranous appendix; they are as high as the apex of the stylus head. The pollinia are elongated with inwardly sloping apex, round base and transparent, outer edge. They are 550 to 630 μm and 150 to 200 μm wide. The caudiculae start at the base of the corpusculum. They are elongated, approx. 150 μm long. The corpusculum is 600 to 650 μm long and 250 to 300 μm wide. The stylus head is pentagonal in cross-section with five lobes that alternate with the stems. The apex of the stylus head is columnar, it is 1 to 1.2 mm long and measures approx. 0.5 mm in diameter at the base. The ovary is linear, approx. 2 mm long, each carpel is approx. 0.5 mm wide at the base. Fruits and seeds have not yet been observed.
Similar Art
Hoya ruthiae is similar to Hoya uncinata Teijsm. & Binn. Both species have a clear milky sap , a corolla with deeply incised petal lobes and a corpusculum that is almost as long as the pollinia. The spread corolla of Hoya uncinata is however smaller (1.5 to 1.7 cm in diameter) and has ovoid Kronblattzipfel. The corolla of Hoya ruthiae measures 1.8 to 2.2 cm in diameter and has narrow, lanceolate petal tips.
Geographical distribution and habitat
Hoya ruthiae is only known from the type locality near Bukit Baturong, Lahad Datu District , Sabah , Malaysia . The species grows there lithophytically on limestone.
Taxonomy
The taxon was described by Michele Rodda in 2015 . The type specimen was collected on limestone on July 7, 2000 near Bukit Baturong, Lahad Datu District, Sabah, Malaysia. The type specimen is kept in the herbarium of the Singapore Botanic Gardens in Singapore under the number Kiew R RK5029 (barcode SING0077484). Other plant material comes from a Hoya nursery in Ratchaburi , Ratchaburi Province , Thailand. This material is also held in the Singapore Botanic Gardens under the number Rodda M MR606.
Hoya ruthiae is named after Ruth Kiew (1946–), who works as a botanist at the Forest Research Institute Malaysia in Kepong ( Selangor , Malaysia). She is the author of numerous works, including on Begonia L. and Gesneriaceae.
It is accepted as a valid taxon online by Plants of the World .
literature
- Michele Rodda: Two new species of Hoya R.Br. (Apocynaceae, Asclepiadoideae) from Borneo. PhytoKeys, 53: 83-93, 2015 doi : 10.3897 / phytokeys.53.5079
- Michele Rodda: Index of names and typus of Hoya (Apocynaceae: Asclepiadoideae) of Borneo. Gardens' Bulletin Singapore, 69 (1): 33-65, 2017 doi : 10.3850 / S2010098116000039 , here p. 52.