Hydnophytum species are epiphytic , perennial herbaceous plants to subshrubs , so some species lignify somewhat. The lower area of the stem axis thickens in a bulbous manner, so they are caudiform, it is a hypocotyl bulb. In this thickening, hollow chambers, so-called " domatia ", are formed. Above the thickening there are one or more, at most, slightly woody side shoots.
The opposite leaves are simple and leathery. They are small, interpetiolare Stipules present, which are preserved or fall off early.
Generative characteristics
At each leaf node only one inflorescence is formed on the side, which contains a few flowers in bundles.
The sessile, four-fold flowers are mostly hermaphroditic or rarely unisexual. The four durable sepals are mostly fused over most of their length, so that often only short calyx teeth can be seen. The four petals are fused cup-shaped to narrowly funnel-shaped. The inside of the corolla tube can be hairy downy. The four stamens arise in the corolla tube and have only very short stamens. The two carpels are one under constant ovary grown. There is only one erect ovule in each ovary compartment . The long to short style ends in a two-lobed stigma. They are mostly heterostylish .
The fissure fruits, which are brightly colored when ripe, are more or less oval to top-shaped and disintegrate into two partial fruits when ripe.
ecology
Hydnophytum species live symbiotically with ants, so they are ant plants ("myrmecophytes"). The plant offers living and nesting spaces, so-called “domatias” and sometimes also food in the form of extra-floral nectaries. There is also myrmecotrophy ; the epiphytic way of life often causes a reduced supply of nutrients and the ants' legacies lead to a better supply of nutrients. The following ant species live together with Hydnophytum species: Crematogaster deformis Sm. , Iridomyrmex cordatus Sm. , Iridomyrmex myrmecodiae Emery. and Pheidole javana Mayr .
The genus Hydnophytum was established in 1823 by William Jack in Transactions of the Linnean Society of London , Volume 14, page 124. The botanical generic name Hydnophytum is derived from the two Greek words hydnon , oidnon for "edible mushroom", "truffle" and phyton for "plant". Hydnophytum formicarum Jack is the type species of the genus. A synonym for Hydnophytum Jack is Lasiostoma Benth.
The genus Hydnophytum belongs to the subtribe Hydnophytinae from the tribe Psychotrieae in the subfamily Rubioideae within the family Rubiaceae .
Hydnophytum species are found in the Andamans , Myanmar , Indochina and in large parts of Malesia as far as the southwestern Pacific Islands . For example, Hydnophytum formicarum Jack is widespread in Malesia or Hydnophytum ferrugineum P.I. Forest. occurs only in the Australian state of Queensland . 42 species are native to New Guinea and the islands belonging to it.
There are around 50 to 90 species of Hydnophytum :
Hydnophytum acuminicalyx Jebb & CRHuxley : It was first described in 2019 from Papua New Guinea.
Christian Puff et al .: Rubiaceae in the Flora of Thailand , manuscript not yet printed: online.
AFSL Lok, HTW Tan: Tuberous, epiphytic, rubiaceous myrmecophytes of Singapore. In: Nature in Singapore , Volume 2, 2009, pp. 231–236: PDF.
Individual evidence
↑ a b c
Rafaël Govaerts, 2003: World Checklist of Selected Plant Families Database in ACCESS: 1-216203. The Board of Trustees of the Royal Botanic Gardens, Kew. Rafaël Govaerts (Ed.): Hydnophytum. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved June 3, 2020.
↑ a b c d e f
MHP Jebb, CR Huxley: The tuberous epiphytes of the Rubiaceae 7: a revision of the genus Hydnophytum. In: Blumea , Volume 64, 2019, pp. 23-91.
