Orchid Information - Genus Bulbophyllum section Polymeres

Genus Bulbophyllum section Polymeres grades morphologically into Bulbophyllum sections Brachypus and section Papulipetalum. Uniting all three would leave a group without a distinguishing character (the latter two do not have a widened and winged column foot typical for section Polymeres), and keeping all three apart yields sectional boundaries which are partly arbitrary. The boundaries also divide a few species groups which otherwise are rather similar. Here, the three are kept separate, with the note that further investigation is needed. This should include the value of characters now ignored, such as rostellum shape.

Genus Bulbophyllum section Polymeres includes a wide range of different growth forms (states: rhizome creeping to straggling/ascending to pendulous), and pseudobulb morphologies (states: young shoots arising from the basal node, not fused to the pseudobulb/ditto, fused to the pseudobulb/young shoots arising above the basal node). The series below are based on these characters. Possibly, they are artificial; see the note below series a. The couples: series b and c, and series c and d each include species which show marked similarity apart from the distinguishing characters. Each series includes a suite of species with the same general flower morphology including that of the lip: outline elliptic, ovate or oblong, adaxial surface without ridges, glabrous, abaxial surface papillose or hirsute, particularly in the middle part (e.g. Bulbophyllum betchei F. Muell.). Each series also includes species with a widely deviating lip morphology, but deviating differently per series.

Within section Polymeres, Vermeulen & O'Byrne (2008: 126) distinguish 3 groups among their newly described Sulawesi species, while admitting that the division has no value elsewhere. Indeed it has not, it is too detailed and leaves many extralimital species unplaceable: all 3 groups are included in series b below.

Schuiteman et all. (2010) distinguish 4 informal series; these are:

Series A. (former section Vesicisepalum)
Sepals (partly) connate.
Includes a small series of species probably of various phylogenetic affinity within section Polymeres. Bulbophyllum ustusfortiter, previously in section Vesicisepalum, is included in section Brachypus.

Series B. (former sections Polymeres, Micromonanthe, Megaloglossum, Elassoglossum)
Rhizomes creeping or straggling, roots spreading. Pseudobulbs distant to clustered. New shoots arising from the basal node of the pseudobulb. Sepals free.

Series C. (former sections Leptopus, Rhizocaulon)
Rhizomes shortly ascending, patent to stiffly or limply pendulous. Roots growing backwards towards the substratum over or alongside the rhizome. New shoots arising from the basal node of the pseudobulb. Sepals free.

Series D. (former sections Fruticicola, Epibulbon)
Rhizomes shortly ascending, patent to stiffly pendulous. Roots growing backwards towards the substratum over or alongside the rhizome. New shoots sprouting above the basal node of the pseudobulb, perforating the pseudobulb over the distance between its basal node and the spot of emergence. Sepals free.

A key to these series runs as follows, see also Fig. 1 (from Vermeulen et al. 2020):

1. Sepals (partly) connate == Series A
1a. Sepals free == 2

2. Rhizomes creeping or straggling. Roots spreading, arising near most pseudobulbs including recently developed ones == Series B
2a. Rhizomes (shortly) ascending, patent to stiffly or limply pendulous. Roots usually growing towards the point of attachment of the plant over or alongside the rhizome. Recently developed shoots usually without roots == 3

3. New shoots arising from a node along the rhizome (fig. 1a) or from the very base of the pseudobulb, not perforating the pseudobulb above its base series C
3a. New shoots emerging above the node from which they originate, perforating the pseudobulb above its base == series D

In series D, the perforated part of the pseudobulb varies in length between species but varies little within species and is therefore of diagnostic value. In some species, the new shoots arise just above the base of the pseudobulb, in others close to the apex.

Fig. 1. Rhizome and pseudobulb morphology in Bulbophyllum section Polymeres. Rhizomes white, pseudobulbs green, flower buds red. Drawing © J.J. Vermeulen, in .J.Verm., Schuit. & de Vogel, Lankesteriana 20(3) (2020) 302, fig. 1.
a–b: New shoots from a node along the rhizome (a), or the basal node of the pseudobulb (b), only fused to the node from which they originate, not to the rhizome or pseudobulb (in b pseudobulb flanges are clasping the rhizome). c–e: New shoots from above the node from which they originate, because they are fused to or perforating the pseudobulb.


At present, Bulbophyllum section Polymeres comprises approximately 170 (provisionally) accepted species (232 names) (Vermeulen et al. 2020).

In New Guinea Bulbophyllum section Polymeres contains 141 species and 1 variety:

Bulbophyllum acutilingue
Bulbophyllum amblyacron
Bulbophyllum anjae
Bulbophyllum appressum
Bulbophyllum atrolabium
Bulbophyllum atroviride
Bulbophyllum aundense
Bulbophyllum aureobrunneum
Bulbophyllum betchei
Bulbophyllum bigibbosum
Bulbophyllum bismarckense
Bulbophyllum bombycinum
Bulbophyllum caputgnomonis
Bulbophyllum cerastes
Bulbophyllum chaetostroma
Bulbophyllum chaunobulbon
Bulbophyllum championii
Bulbophyllum chrysanthum
Bulbophyllum chrysotes
Bulbophyllum ciliipetalum
Bulbophyllum cochlioides
Bulbophyllum commissibulbum
Bulbophyllum compressilabellatum
Bulbophyllum condensatum
Bulbophyllum curvicaule
Bulbophyllum cyclopense
Bulbophyllum dawongense
Bulbophyllum debruynii
Bulbophyllum dendrobioides
Bulbophyllum densifolium
Bulbophyllum dependens
Bulbophyllum dictyoneuron
Bulbophyllum djamuense
Bulbophyllum dologlossum
Bulbophyllum ellipticum
Bulbophyllum elodeiflorum
Bulbophyllum entomonopsis
Bulbophyllum epapillosum
Bulbophyllum epibulbon
Bulbophyllum erioides
Bulbophyllum erythrosema
Bulbophyllum erythrostictum
Bulbophyllum eutoreton
Bulbophyllum exiguiflorum
Bulbophyllum exilipes
Bulbophyllum falcatocaudatum
Bulbophyllum farciminiferum
Bulbophyllum fasciculatum
Bulbophyllum flagellare
Bulbophyllum folliculiferum
Bulbophyllum fruticicola
Bulbophyllum fruticulum
Bulbophyllum fusciflorum
Bulbophyllum futile
Bulbophyllum galliaheneum
Bulbophyllum glanduliferum
Bulbophyllum goliathense
Bulbophyllum gracilicaule
Bulbophyllum gramineum
Bulbophyllum gymnothema
Bulbophyllum hellwigianum
Bulbophyllum howcroftii
Bulbophyllum hystricinum
Bulbophyllum icteranthum
Bulbophyllum idenburgense
Bulbophyllum imbricans
Bulbophyllum intonsum
Bulbophyllum ischnopus
Bulbophyllum ischnopus var. rhodoneuron
Bulbophyllum ischyron
Bulbophyllum kempfii
Bulbophyllum lamelluliferum
Bulbophyllum lamii
Bulbophyllum leptobulbon
Bulbophyllum leptopus
Bulbophyllum leve
Bulbophyllum ligulatum
Bulbophyllum lipochilum
Bulbophyllum lonchophyllum
Bulbophyllum longicaudatum
Bulbophyllum longirostre
Bulbophyllum lorentzianum
Bulbophyllum luteum
Bulbophyllum maijenense
Bulbophyllum marginatum
Bulbophyllum maxillare
Bulbophyllum melinanthum
Bulbophyllum microbulbon
Bulbophyllum microtes
Bulbophyllum mimiense
Bulbophyllum muriceum
Bulbophyllum nannae
Bulbophyllum nasica
Bulbophyllum nasilabium
Bulbophyllum nebularum
Bulbophyllum neoguineense
Bulbophyllum neopommeranicum
Bulbophyllum nudicaule
Bulbophyllum odontopetalum
Bulbophyllum oreogenum
Bulbophyllum orthoraphe
Bulbophyllum papuliglossum
Bulbophyllum paululum
Bulbophyllum perforans
Bulbophyllum pisibulbum
Bulbophyllum plagiopetalum
Bulbophyllum planiplexum
Bulbophyllum planitiae
Bulbophyllum polyphyllum
Bulbophyllum pseudotrias
Bulbophyllum pulvinatum
Bulbophyllum purpurellum
Bulbophyllum quadrangulare
Bulbophyllum quadrichaete
Bulbophyllum radula
Bulbophyllum rhodoglossum
Bulbophyllum rinkei
Bulbophyllum rubipetalum
Bulbophyllum rubromaculatum
Bulbophyllum rugulosum
Bulbophyllum sannio
Bulbophyllum sawiense
Bulbophyllum schistopogon
Bulbophyllum singuliflorum
Bulbophyllum sphaenopus
Bulbophyllum spongiola
Bulbophyllum squamiplectum
Bulbophyllum staetophyton
Bulbophyllum stagmatoglossum
Bulbophyllum subium
Bulbophyllum tectipetalum
Bulbophyllum teinodragma
Bulbophyllum tricaudatum
Bulbophyllum trivenosum
Bulbophyllum tumoriferum
Bulbophyllum undatilabre
Bulbophyllum zebrinum
Bulbophyllum zygochilum