Basal pinna of Orthiopteris firma, showing quadripinnatifid dissection and terminology. bipinnate segment 2nd order. isomorphic segments 2nd and 3rd order, arrows: ultimate segments. Franc 335 (K).

 
 
  Part of: Luong TT, Hovenkamp PH, Sosef MSM (2015) Revision of the fern genus Orthiopteris (Saccolomataceae) in Malesia and adjacent regions. PhytoKeys 53: 39-71. https://doi.org/10.3897/phytokeys.53.4955