European Journal of Environmental Sciences 125 An intriguing morphologicAl vAriAbility of Platanthera S.l. Petr G. efimov Herbarium, Komarov Botanical institute of the russian Academy of Sciences, Prof. Popov str. 2, Saint-Petersburg, 192288, russia. e-mail: [email protected], [email protected] el. and fax: +78123460839 AbstrAct The morphology of 38 species of the genus Platanthera s.l. was investigated by means of light and electron microscopy. Particular attention was paid to the structure of gynostemium and pollinaria. The species investigated represent 10 major lineages of the genus, all being recognized as sections or segregate genera in various taxonomical treatments. Considerable morphological variability was con- firmed for Platanthera s.l. The most notably variable structures are tuberoids (root-like, stoloniferous, spherical, etc.), lip (entire, lobed, fimbriate etc.), rostellar lateral lobes (flat, concave, bursicle-like), lateral stigma lobes (flat, protruding, etc.) and viscidia (orbicular, lanceo- late, sub-linear, deeply concave, reduced). The morphology of several taxa confirms that they do not belong to Platanthera s.l., of them Platanthera camtschatica displays relation to Galearis s.l. and P. latilabris, P. clavigera and P. biermanniana – to subtribe Habenariinae. In many cases the morphology confirms the monophyly of the lineages within Platanthera s.l., as Tulotis, Limnorchis etc., although more thorough sampling is needed. Some of those groups correspond to the clades as defined by previously published molecular phylogenies (Hapeman and Inoue 1997, Bateman et al. 2009). The morphological polymorphism in Platanthera s.l. (especially gynostemium structure) seems to be higher than in many other large genera of the subtribe Orchidinae, as Dactylorhiza, Ophrys or Orchis, and led to recognition of several segregate genera within Platanthera s.l. However, lesser genetic polymorphism revealed by molecular markers gives evidence for morphological plasticity (in particular, in gynostemium structure) and rapid morphological evolution of this group. Keywords: Platanthera, gynostemium, morphological plasticity, viscidium, bursicle Introduction Generally, Platanthera s.l. is the subject of signifi- cant taxonomical controversy. This is mainly due to The genus Platanthera rich. belongs to subtribe Or- the problems with generic affiliation of its species, be- chidinae (subfamily Orchidoideae), and taken sensu lato, it cause many segregate genera were described within encompasses about 120 species. They are terrestrial herbs, Platanthera s.l. on the basis of various, more or less except for several humus epiphytes that grow on tree significant morphological distinguishing features. trunks near to ground level. The distribution of the genus Those genera are Limnorchis, Tulotis, Lysiella, Mecosa, covers mostly temperate zone of Northern Hemisphere. Fimbriella, Blephariglottis, Gymnadeniopsis and Pseu- Several species are tropical, but they mostly inhabit dodiphryllum. monotypic Neolindleya was also merged mountainous forests at higher altitudes and do not repre- into Platanthera-complex by some authors. furthermore, sent tropical species de facto. taxonomically Platanthera several genera were assigned to this complex on the ba- is a rather poorly known genus, which is mainly due to sis of new molecular phylogenetic data, such as Piperia the paucity of taxonomic knowledge of numerous Asiatic and Diphylax (Bateman et al. 2009). Probably their list and some American representatives of the genus. to cer- will be enlarged in the future with further sampling of tain extent, inconspicuous habit of the plant along with the taxa. Three molecular phylogenies of Platanthera s.l. usually small flowers might be a reason that this genus have been published (Hapeman and inoue 1997; Bateman has not been investigated thoroughly before. et al. 2003; Bateman et al. 2009). Detailed taxonomical studies of the genus based on main aim of this study was to describe the morphol- thorough morphological analysis were undertaken for ogy of species belonging to Platanthera s.l. in relation Japan and taiwan by Ken inoue (inoue and Lin 1980; to the taxonomy of this group. especially gynostemium inoue 1982, 1983). 15 species reaching russia were also structure of many representatives of this group remains reviewed in detail (efimov 2006, 2007a, 2007b), the same not sufficiently investigated. But it is very important for as for Korean peninsula (Lee and Choi 2005). other tax- taxonomy, because gynostemium is traditionally viewed onomic studies of the genus include mainly treatments as taxonomically informative in this genus. However, it in different ‘floras’, of whichf ‘ lora reipublicae Popularis should be mentioned that in this study we covered only Sinicae’, ‘flora of China’ and ‘flora of North America part of morphological variability of this group, both north of mexico’ cover the most species-rich territories concerning organs that were analyzed in detail, and for Platanthera in the world. concerning the sampling of the taxa. especially impor- Efimov,p . g. (2011): An intriguing morphological variability of Platanthera s.l. European Journal of Environmental Sciences, vol. 1, no. 2, pp. 125–136 126 p. g. Efimov tant is further sampling of North American taxa, as our Table 1 List of voucher specimens for the investigations of gynoste- sampling of the species from that continent proved to be mium structure. rather superficial. No Species Data from the label for the purpose of simplicity, i divided the genus Plat- 1 P. bifolia Russia, VII 2004, Efimov (flowers in alcohol) anthera into the formal groups. Some of them are named 2 P. chlorantha Russia, VI 2005, Efimov (flowers in alcohol) after the names of smaller genera of Platanthera s.l. to 3 P. densa Russia, VI 2006, Efimov (flowers in alcohol) which they were once assigned. others are named after 4 P. dyeriana China, VIII 2006, Jin 8368 (PE) the names of corresponding sections. few groups have 5 P. mandarinorum Russia, VII 2007, Efimov (flowers in alcohol) been formed here for the first time and named by listing 6 P. metabifolia Russia, VI-VII 2007, Efimov (flowers in all taxa which they include. alcohol) 7 P. oligantha Russia, VII 1928, Sukaczev and Bryzhzhev s.n. (LE) Materials and Methods 8 P. oreophila China, VII 1937, Yü 7178 (PE) 9 P. tipuloides Russia, VI 2007, Efimov (flowers in alcohol) The study is based on the analysis of herbarium speci- 10 P. epiphytica Vietnam, X 2005, Averyanov et al. (LE) mens and flowers preserved in 70% alcohol.f or the study 11 P. elliptica New Guinea, s.d., Hongfan s.n. (PE) of the flower morphology from dried specimens, 1–2 12 P. singgalan- China, X 1935, Indonesia, Zollinger 1706 young flowers (or flower buds ready to open) were -im gensis (LE) mersed into the hot water (80–100 °C) for 5–15 minutes 13 P. bakeriana China, VIII 1981, collector unknown 3016 (PE) and examined under the light microscope. Herbarium 14 P. exelliana China, VIII 1938, Yü 22219 (PE) collections of Le (Saint-Petersburg, russia), Pe (Beijing, 15 P. handel-mazettii China, VIII 2006, Jin 8369 (PE) China) and K (Kew, Great Britain) were studied. 16 P. juncea China, VIII 2007, Jin 9154 (PE) fresh flowers of some species were collected by the 17 P. leptocaulon China, VII 1981, collector unknown 01381 author in russia (Leningrad region, Primorye territory, (PE) Sakhalin region) and analyzed under the light micro- 18 P. roseotincta China, VII 2010, Jin et al. 1291 (PE) scope or scanning electron microscope JSm 6390-LA. 19 P. stenantha China, VIII 2010, Jin et al. 2833 (PE) for Sem, the material was initially subjected to a critical 20 P. sachalinensis Russia, VI 2007, Efimov (flowers in alcohol) point drying following a standard procedure of ethanol, acetone and isoamylacetate treatments and sputter-coat- 21 P. latilabris China, VIII 2010, Jin et al. 2591 (PE) ed with platinum/palladium alloy. The details of seed 22 P. clavigera China (PE) and pollen surface were investigated under the electron 23 P. biermanniana China, VIII 2007, Jin 9132 (PE) microscope of older version (JEOL JSm 35C) without 24 P. convallariifolia Russia, VII 2007, Efimov (flowers in alcohol) critical point drying procedure. 25 P. dilatata Russia, VIII 2000, Tatarenko (LE) in total, the gynostemium structure of 38 species of 26 P. finetiana China, VII 1958, Yang 58846 (PE) Platanthera was examined (table 1). All identifications 27 P. fuscescens Russia, VI 1909, Diukina 172 (LE) of herbarium specimens from Asia were verified by the 28 P. hologlottis Russia, VII 2005, Efimov (flowers in alcohol) author in relation to his revision of the genus for Pan- 29 P. japonica China (PE) Himalayan flora (in prep.), or corresponding to the f“ lora 30 P. sinica China, VIII 1981, collector unknown 02492 of North America North of mexico” (Sheviak 2003), for (PE) American taxa. 31 P. ussuriensis Russia, VII 2005, Efimov (flowers in alcohol) 32 P. whangsha- China, VII 1985, Chen and Ma 1143 (PE) nensis results 33 P. elongata USA, VII 1896, Hansen 1864 (LE) 34 P. chorisiana Russia, VII 2007, Efimov (flowers in alcohol) Morphological descriptions of the subgroups 35 P. camtschatica Russia, VII 2007, Efimov and Andronova in Platanthera s.l. (flowers in alcohol) 36 P. integra USA, VIII 1939, Godfrey and Tryon 936 (LE) 1. Platanthera s.str. 37 P. psycodes USA, s.d., Martz s.n. (LE) Platanthera sensu stricto remains largely polymorphic 38 P. blephariglottis USA, s.d., Wiedemann s.n. (LE) in its morphology. i divided it further into smaller groups 39 Habenaria Russia, VII 2005, Efimov (flowers in alcohol) and discuss them separately. Those groups were either linearifolia treated as taxonomic sections (sect. Mecosa, sect. Stigma- tosae) or just represent the associations of species erected P. man darinorum, P. metabifolia, P. oligantha, P. oreophila, here on the basis of the species morphology. P. tipuloides). fig. 1a; fig. 2a–b. orthotropic shoot 1. tuberoids ovate to narrowly fu- 1a. Platanthera sensu strictissimo, including Ly- siform (but in Lysiella not thickened and root-like), with siella (P. bifolia, P.