Wassel, A.C. & W.L. Applequist (2020). A revision of Homalium sect. Nisa (Salicaceae) endemic to Madagascar. Candollea 75: 1–23. In English, English & French abstracts.
Homalium sect. Nisa (Noronha ex Thouars) Baill. is endemic to Madagascar and has included four recognized species. A new revisionary treatment of the section is presented and an identification key is provided. Eleven species are recognized, including eight that were formerly part of the Homalium nudiflorum (DC.) Baill. species complex. Four species and one subspecies are newly described: Homalium antilahimenae Wassel & Appleq., Homalium mandenense Wassel & Appleq., Homalium pachycladum Wassel & Appleq., Homalium tenue Wassel & Appleq., and Homalium stelliferum subsp. andapense Wassel & Appleq. Homalium ciliolatum (Sleumer) Wassel & Appleq. is newly recognized at species level and the new combination Homalium retusum (Blume) Wassel & Appleq. is further published. Four lectotypes are designated including a second step. Taxonomic novelties are provided with line drawings or scans of their holotypes. Risk of extinction assessments indicate that three taxa are “Endangered” and three “Vulnerable”. Occasional hybridization is observed. Some specimens are not classifiable and it is possible that other unrecognized species exist.