A key to the subspecies Tridactyle bicaudata
| 1a | Plants epiphytic; leaves 60-120 mm long; flexuose | subsp. bicaudata |
| 1b | Plants lithophytic; leaves 30-60 mm long; stiff and arcuate | subsp. rupestris |
References:
World Checklist of Monocotyledons. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the Internet; http://www.kew.org/wcsp/monocots/ accessed 21.03.2017
