1a. Habitat: Perennial, caespitose | |
 2a. Glumes similar | |
  3a. Leaf blade surface smooth on both sides | |
   4a. Spikelet callus hairs white, 1.5× length of spikelets | |
    5a. Rhachis internode 3.5–4 mm long | |
     Tripidium arundinaceum | |
    5b. Rhachis internodes 6–7 mm long | |
     Tripidium procerum | |
   4b. Spikelet callus hairs yellow or red, 2–3× length of spikelet | |
     Tripidium rufipilum | |
  3b. Leaf blade surface scabrous — rough on both sides | |
     Tripidium strictum‡ | |
 2b. Glumes dissimilar | |
  6a. Glumes exceeding apex of florets, lower glumes elliptic, upper glumes lanceolate | |
     Tripidium ravennae‡ | |
  6b. Glumes 1× length of spikelet, lower glume 2 keeled, lower glume hairs 4–9 mm long, upper glume without keels | |
     Tripidium bengalense‡ | |
1b. Habitat: Perennial, culms solitary | |
 Key characters: Culms erect, 70–100 cm long, 5–15 mm diameter, rhizomes short, leaf blade hairy at base. Spikelet callus hairs 3–6 mm long. | |
     Tripidium kanashiroi |