Hoya imbricata
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Hoya imbricata , deciduous leaves and stem axes |
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| Decne. |
Hoya imbricata is a plant of the genus of wax flowers ( Hoya ) of the subfamily of asclepiadoideae (Asclepiadoideae). It occurs in the lowland rainforests of Indonesia and the Philippines and lives in symbiosis with ants.
description
Vegetative characteristics
Hoya imbricata is a perennial herbaceous plant and grows epiphytically, climbing with roots at the nodes and anchoring itself to the ground. The stem axis and the leaves are close to the substrate, usually the bark of trees. The shoot axes can be several meters long. The leaves are very short stalked and cover nodes and internodes. Only one leaf emerges from each knot. The dark green, stiff, thin, clock-glass-shaped and clapboard-like arranged leaf blades are round to almost square with a diameter of 8 to 10 centimeters with a heart-shaped to rounded base. The underside of the leaves is purple in color and the dark green upper side is glabrous, shiny, occasionally with silver speckles.
Generative characteristics
The bald inflorescence stem is curved upwards and is up to 10 centimeters long. The upright, golden inflorescence has a diameter of 6 to 8 centimeters and 15 to 28 flowers, which form a straight edge. The flower stalks are of different lengths and bare.
The hermaphrodite flowers are radially symmetrical and five-fold. The bald sepals are narrow, elliptical and tapering to a point. The cream-colored to light yellow corolla has a diameter of 8 to 10 millimeters. The thin, very long and finely pointed tips of the petals are strongly bent back and bald on the outside, dense on the inside, finely hairy. The corolla is whitish to light yellow. The outer extension of the staminal secondary corolla lobes are narrow, rounded and lie flat, the inner extension is elliptical and rises steeply and high. The long, pointed extensions of the stamens rise above the corolla like tufts.
The paired, spindle-shaped follicles are straight to slightly curved and pointed; the surface is smooth. The brown and narrow seeds are 7 millimeters long. Your head of hair is up to 14 millimeters long.
Synecology
Hoya imbricata lives in symbiosis with ants, species of the genus Philidris ( dolichoderinae / Dolicoderinae). These ants are scavengers and hunters and build their nests under the watch-glass-shaped leaves that are laid out on the substrate. The cavities formed by the leaves and populated by ants are also called "myrmecodomatia". Free nests of these species are not known, but in the case of Hoya imbricata the same Philidris species uses different " ant plants " to create their nests (here also the similarly shaped leaves of Dischidia imbricata ). The Philidris workers also bring earth particles and detritus into their nests. In addition, cuticle remains from captured insects, but also dead workers and excrement accumulate in the mymecodomatia under the leaves. The roots of the host plant growing into these cavities therefore find a nutrient-rich substrate. The ants make a contribution to the nutrient supply of the epiphytes that should not be underestimated. Symbioses of plants with ants have emerged several times in Africa and Southeast Asia since the Miocene.
Occurrence
Hoya imbricata occurs in Indonesia ( Sulawesi ) and the Philippines . In the tropical rainforests it grows preferentially on mango trees ( Mangifera indica ), more rarely also on breadfruit trees ( Artocarpus altilis ) and other tree species.
Taxonomy and systematics
The first description of Hoya imbricata was in 1844 by Joseph Decaisne . Synonyms for Hoya imbricata Decne. are: Hoya maxima Teijsm. & Binn. , Conchophyllum maximum H. Karst. , Hoya imbricata var. Basi-subcordata coord. And Hoya pseudomaxima coord.
One can distinguish between two subspecies:
- Hoya imbricata subsp. imbricata : It occurs in the Philippines and Sulawesi.
- Hoya imbricata subsp. megapollinia Kloppenb. : It occurs in the Philippines.
supporting documents
literature
- Christiane Hoffmann, Ruurd van Donkelaar, Focke Albers: Hoya. In: Focke Albers, Ulli Meve (Hrsg.): Succulents Lexicon Volume 3 Asclepiadaceae (silk plants). Pp. 147–160, Ulmer, Stuttgart 2002, ISBN 3-8001-3982-0 ( Hoya imbricata : p. 153).
- Surisa Somadee and Jens Kühne: Hoya 200 different wax flowers. 96 pp., Formosa-Verlag, Witten 2011 ISBN 978-3-934733-08-4 (pp. 55–56)
- Anders Wennström and Katarina Stenman: The Genus Hoya - Species and Cultivation. 144 p., Botanova, Umeå 2008 ISBN 978-91-633-0477-4 (p. 70)
- Dale Kloppenburg, Ann Wayman: The World of Hoyas - a book of pictures. A revised version. Orca Publishing Company, Central Point, Oregon 2007, ISBN 0-9630489-4-5 , p. 124 short description and p. 125 photo by Dale Kloppenburg
Individual evidence
- ↑ a b Andreas Weißflog: Free nesting of ants (Hymenoptera: Formicidae) in the crown region of humid tropical forests of Southeast Asia. Inventory and phenology, ethoecology and functional analysis of nest building. Dissertation to obtain a doctorate in natural sciences, submitted in the department of biology and computer science at the Johann Wolfgang Goethe University in Frankfurt am Main, 2001 PDF.
- ↑ Guillaume Chomicki, Susanne S. Renner: Phylogenetics and molecular clocks reveal the repeated evolution of ant-plants after the late Miocene in Africa and the early Miocene in Australasia and the Neotropics. In: New Phytologist , 2015. doi : 10.1111 / nph.13271
- ↑ Augustin-Pyrame de Candolle : Prodromus systematis naturalis regni vegetabilis: sive enumeratio contracta ordinum generum specierumque plantarum huc usque cognitarum, juxta methodi naturalis normas digesta. Part: 8. Sistens Corolliflorarum Ordines 13. 684 S., Paris, Treuttel & Würtz, 1844. Online at Biblioteca Digital Real Jardín Botánico CSIC (Description of Hoya imbricata by Joseph Decaisne: p. 637)
- ↑ Sijfert Hendrik Koorders: note about Hoya imbricata Callery ex Decaisne and Hoya pseudo maxima Kfs. in the Filipines on the basis of some herbarium specimens from the Bureau of Science in Manila. In: The Philippine Journal of Science , Volume 15, Manila 1919, pp. 263-265. scanned at www.biodiversitylibrary.org .
- ↑ a b Rafaël Govaerts (Ed.): Hoya - World Checklist of Selected Plant Families des Royal Botanic Gardens, Kew. Last accessed on November 16, 2018.
