Bulbophyllum sect. Brachystachyae

Nguyen, Dinh Hiep, Averyanov, Leonid V., Dang, Van Son, Pham, Phuoc Dien, Maisak, Tatiana, Bui, Van Huong, Dang, Minh Quan & Truong, Ba Vuong, 2021, Bulbophyllum xuansonii (Orchidaceae), a new miniature orchid from northern Vietnam and new national record of B. gracilipes, Phytotaxa 522 (2), pp. 150-156 : 155-156

Artificial key to species of Bulbophyllum sect. Brachystachyae in the flora of Vietnam

1a. Inflorescence with dense flowers (flowers touching each other) .......................................................................................................2

1b. Inflorescence with lax flowers (flowers do not touch each other) .....................................................................................................9

2a. Inflorescence cylindrical, up to 8 cm long .........................................................................................................................................3

2b. Inflorescence globular or ovoid, less than 2.5 cm long......................................................................................................................4

3a. Dorsal sepal adaxialy papillose; stelidia pointing forward............................................................................................. B. ustulatum 3b. Dorsal sepals adaxially smooth; stelidia curved upwards ............................................................................................ B. khasyanum

4a. Pseudobulbs much reduced, hardly visible, less than 5 mm long ......................................................................................................5

4b. Pseudobulbs distinct, to 11 mm long..................................................................................................................................................8

5a. Apex of petals truncate, margin erose .................................................................................................................................. B. repens

5b. Apex of petals rounded or shortly mucronate, margin entire.............................................................................................................6

6a. Leaf blade to 6 cm long; inflorescence longer than 3 cm ...................................................................................................................7

6b. Leaf blade to 2.5 cm long; inflorescence less than 2 cm long......................................................................................... B. xuansonii

7a. Flowers uniformly green or pale yellow, pedicellate; lower margin of stelidia with distinct, oblique triangular tooth ...................... ..................................................................................................................................................................................... B. xylophyllum

7b. Flowers dark purple-red, sessile; lower margin of stelidia with inconspicuous, rounded tooth ..................................... B. gracilipes

8a. Pseudobulbs globular, erect; stelidia without upper teeth, lower teeth triangular............................................................ B. apiferum

8b. Pseudobulbs ovoid, oblique; upper teeth in stelidia present, rounded, lower teeth rounded ............................................. B. poilanei

9a. Stelidia and upper teeth equal, lower teeth ca. 0.5 mm long........................................................................................ B. bidoupense

9b. Teeth of stelidia unequal, lower teeth ca. 0.2 mm long.................................................................................................... B. alcicorne