BULLETIN - Heliconia Society International

THE PAGE BULLETIN 12 / JANUARY 2005 THE BULLETIN / JANUARY PAGE 2010 13The Genus PlagiostachysJana Leong-Škorničková, Senior Researcher(Zingiberaceae), Herbarium,Singapore Botanic Gardens, 1 ClunyRoad, 259569 Singapore(jana_SKORNICKOVA@nparks.gov.sg)Reprinted with permission from Gardenwise (SingaporeBotanic Gardens), vol. 30: 35 (January 2008). Photos bythe author.This genus was first established in 1899 by the formerdirector of the Gardens, H.N. Ridley. Since then, almost30 species have been described from Indochina toMalesia, with its centre of diversity in Borneo. Thesestately gingers usually have rather small flowers. Theseare tightly arranged in dense slanting spikes, which breakout from the leafy shoot usually somewhere in the middleor lower half of the pseudostem, and rarely close tothe ground. Their inflorescences are often covered in aslimy mass. The peculiar position of inflorescence inspiredRidley to choose its botanical name based on theGreek words Plagio meaning oblique and stachys referringto the spike-like inflorescence.The study of this genus is particularly challengingas most flowers of Plagiostachys tend to quickly disintegrateinto slimy thick mass. However, modern molecularapproaches may clarify the position of this genus especiallyin relation to the genus Alpinia, which seemsclosely related. Recent DNA-based studies of the tribeAlpinieae (where genera Alpinia, Plagiostachys, Amomumand several others belong) have shown that somemembers of the genus Plagiostachys may actually becloser to others in the genus Alpinia. Unfortunately, gardenersmay have to put up with likely name changes inthe near future.Plagiostachys albiflora is one of the first species described.Found on Mt. Kukub in Johor State, Peninsular Malaysia in 1908by Ridley, this species seems to be widely distributed. In Borneo,it is reported to grow abundantly in wet places on the edgesof lowland forests. It displays a certain level of variability requiringdetailed studies of living materials and molecular studies toelucidate this species complex. Under the magnifying lens, thetiny flower of P. albiflora (less than 1 cm long) reveals its beautywith its single stamen placed above the petal-like labellum. Thespecific name albiflora, means ‘white flower’. Interestinglyenough, with the yellow centre of the labellum and red lines at itsedges, the flowers are not really white, as one would expect.Fortunately, Ridley’s original description published for this speciesmentioned this colour pattern, removing doubts of the identityof this species.Plagiostachys breviramosa, a new species recently described in1999 by Jill Cowley, has small and delicate yellow flowers. Itoccurs in many parts of Borneo. Unusual for its branched inflorescence,it is one of the Plagiostachys species which does notexude a slimy mass. The inflorescence is rather dry after theflowering finishes and its dark red fruits are ovoid and smooth.Plagiostachys crocydocalyx is one of the stateliest specieswidely distributed in Borneo. German botanist K.Schumann originally described it as a member of thegenus Alpinia in 1899, but the species was transferredto the genus Plagiostachys in 1972. Its round fruits arefull of aromatic seeds with sour-sweet arils. Local peopleoften chew them.