Biodiv. Res. Conserv. 32: 9-24, 2013 BRC www.brc.amu.edu.pl DOI 10.2478/biorc-2013-0012 Submitted 22.11.2012, Accepted 15.06.2013 The genus Bilabrella Lindl. (Orchidaceae, Habenariinae): general characteristic and research history of the genus Marta Kras* & Dariusz L. Szlachetko Department of Plant Taxonomy and Nature Conservation, the University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland * corresponding author (e-mail: [email protected]) Abstract: The genus Bilabrella (Habenarinae, Orchidaceae) was described by Lindley in 1834, but within next years, different authors incorporated it as the section of the genus Habenaria Willd. From 2003, Szlachetko and Kras stated that there were no grounds for distinguishing the sections Bilabrellae and Replicatae. They restored the genus Bilabrella, transfering to it 93 species from the section Replicatae and four species new to science were described. The poor condition of the old plant materi- als, the lack of some type specimens for many species described by Schlechter and problems with a series of transitional forms between some species are only few reasons, why the revision of the genus has not been published so far. Bilabrella comprises orchids found in Sub-Saharan Africa, Madagascar and neighbouring islands. Bilabrella differs from other Habenariinae in its unique combination of features. y Key words: taxonomy, research history, Orchidaceae, Habenaria, Bilabrella, Africa LOGEN y PH 1. Introduction In 2000, Szlachetko and his team started to develop a taxonomic revision of Habenaria sensu latissimo. One of the most interesting representatives of the As a result of this work, the original Willdenowian AND order Orchidales is the genus Habenaria Willd. It was definition of the genus was restored, the boundaries of described by the German botanist Willdenow in 1805. Habenaria sensu stricto defined, the number of species y Since that time, it has embraced terrestrial orchids, contained within it limited and a range of new genera usually with inconspicuous green or white flowers. described (Szlachetko 2003a, 2003b, 2003c, 2003d; As exploration of tropical areas progressed more and Szlachetko et al. 2003; Szlachetko & Kras-Łapińska more, new Habenaria species were described, con- 2003; Szlachetko & Sawicka 2003a, 2003b; Szlachetko ONOM siderably expanding the boundaries of the genus, and 2004a, 2004b, 2004c, 2004d, 2004e, 2004f; Szlachetko x hence distorting its original definition. Not that long & Margońska 2004; Szlachetko 2005a, 2005b; Szla- ago, Habenaria comprised about 600 species and the chetko & Kras 2006a, 2006b, 2006c, 2006d, 2006e, ta number of published names within it amounted to circa 2006f). As a consequence of in-depth research of the 2400. collections maintained in Herbaria all over the world, y, In 1901, Kraenzlin published the first revision of and analysis of the original diagnoses, researchers Habenaria in which he provided descriptions of the have been able to enhance our knowledge of this plant sections and species known to science at that time. group. Since then, many new species have been described Unfortunately, conducting research on Habena­ and application of his Habenaria infrageneric clas- ria encountered many difficulties, one of the most sification often became impossible. Kraenzlin’s revi- major was the destruction of Schlechter’s Herbarium sion turned out to be non-predictive and soon proved with its multiple type materials during the World ARIABILIT inadequate. War II. V ©Adam Mickiewicz University in Poznań (Poland), Department of Plant Taxonomy. All rights reserved. 10 Marta Kras & Dariusz L. Szlachetko The genus Bilabrella Lindl. (Orchidaceae, Habenariinae): taxonomic revision Bilabrella Lindl. is a taxon that is scarcely reco- upwards; the rostellum evenly linear-lanceolate, with gnized, despite having been described nearly 180 years fleshy, stalked rostellophores; petiolate leaves with ago. So far, no revision of the genus has been published, narrow blade; elongate inflorescence. None of these so it is not known how many species it includes, which features could differentiate Bilabrella from the broadly of those described should be distinguished and which defined Habenaria. A few years later, Lindley himself should be regarded merely as synonyms. Its high in- subsumed his genus under Habenaria. frageneric variability in relation to the structure of the In the monograph “Beiträge zu einer Monographie perianth segments and the presence of series of species der Gattung Habenaria Willd. (Allgemeiner Teil.)” in that are morphologically similar make Bilabrella a very 1891, Kraenzlin proposed H. macroceratitis Willd. as interesting subject of study. Like any taxon whose sys- type species for the genus. This, however, did not lead tematic position is unclear, it does require taxonomic to defining unequivocal boundaries for the genus itself, research. nor for the section within it. The aim of the present work is to prepare a back- As a consequence, Rendle (1895), when describing ground to the taxonomic revision of Bilabrella. The first a new species – Habenaria altior in “Flora of Eastern stage of the research involved determining the differen- Tropical Africa” – included it in the section Bilabrel­ ces between Bilabrella and other African Habenariinae. lae, and a similar one, Habenaria ndiana in the section The secondly, an infrageneric classification, the keys Replicatae. Rendle did not indicate the differences to determination and descriptions of all species are between these sections nor did he justify his view on proposed. this issue. In 1901, another work by Kraenzlin was published 2. History of the research on Bilabrella Lindl. which was only a revision of Habenaria, its title being “Orchidacearum Genera et Species”. Among Within the order Orchidales, a dozen or so genera other things he mentioned 28 species there which were described that comprise a considerable number of he included in the section Replicatae. He stated that species. Until fairly recently, one of the larger taxa at the differences between Replicatae and Bilabrella the generic level was Habenaria Willd., which included were so slight that these two should be treated as about 2100-2450 species names (according to The one. Kraenzlin defined the section Replicatae by International Plant Name Index 2013 and Tropicos- the following features: labellum divided into three Missouri Botanical Garden database 2013). The genus lobes, petals divided into two lobes; stigma with long was proposed by the German botanist, Willdenow, in stigmaphores. the fourth edition of “Species Plantarum” published In 1913, Bolus published “Orchids of Southern in 1805, where he included a description of two spe- Africa”. Knowing the defects of the Kraenzlin’s study, cies, namely Habenaria brachyceratitis Willd. and and with no intention of revising the whole genus, the Habenaria macroceratitis Willd. Willdenow did not author listed the Habenaria species in an alphabetical indicate the type for the genus, which was standard order. Many researchers followed him. procedure at that time. The quite brief description of the Also in 1913, “Flora Capensis” was published, where new genus caused serious taxonomic repercussions, as there was a chapter on orchids written by Rolfe. He almost all species of terrestrial orchids which originated placed Habenaria, under the number xxIV, offering from tropical or subtropical areas and had white or descriptions of 37 species. Following Bolus, he did not greenish, usually inconspicuous, flowers started to be recognize sections. Based on the Kraenzlin’s revision, included in Habenaria. The confusion in the taxonomy Bilabrella should have included 9 species described by of this group became even greater when Habenaria Rolfe. was made to include genera from the temperate zone One of the best known researchers of African of the northern hemisphere such as Platanthera Rich., orchids and discoverer of many of them was Sum- Coeloglossum Lindl., Piperia Rydb. and some species merhayes, who worked for the Royal Botanic Gardens of Orchis L., Gymnadenia R. Br. and Dactylorhiza at Kew. He described a great number of Habenaria Neck. species. In the early stages of his research on the ge- The genus Bilabrella was described by John Lindley nus, he accepted the existence of the separate sections in 1834. He placed there only one species, Bilabrella Bilabrellae and Replicatae. This clearly results from the falcicornis (Edwards’s Bot. Reg. 20: sub. t. 1701. species descriptions in a series of his articles published 1834). In the generic description, Lindley regarded the in the Kew Bulletin entitled “African Orchids” (1931, following features as diagnostic: fleshy sepals; lateral 1932, 1942, 1960, 1962, 1966, 1968), in wich Habe­ sepals of medium size; leathery, relatively large petals; naria limnophila Summerh. (1931) and Habenaria fleshy labellum with 3 lobes; the anther with elongated pauper (1932) were placed in the sections Replicatae antherophores, which are free and directed forwards or and Bilabrellae, respectively. With time, Summerhayes Biodiv. Res. Conserv. 32: 9-24, 2013 11 acquired more experience in his study of Habenaria reflexed, lateral sepals ending in an apiculus, petals and accepted the Kraenzlin’s proposal, uniting the divided into two basal lobes and gynostemium with two sections into one taxon. Each new taxon descrip- outgrowths were all placed in the section Replicatae. tion by Summerhayes shows great care for detail. In The two species that occur in Gabon were Habenaria