This species, based upon a flowering collection of Spruce (no. 3690) along the Casiquiare River in Territorio Federal Amazonas, southwestern Venezuela, is represented in NY by an isotype specimen, by a fragment of an isotype collection in F, and by photographs of the holotype in K and in B.
Spruce described the leaA-es (Trans. Linn. Soc. 22: 297. 1859) as "(an constanter) ternatim verticillata, 8-10 poll. [24-30 cm] longa, 2-3 [6-9 cm] poll. lata." The isotype specimen at New York shows leaf-blades only 15-16 cm long and 4-5.5 cm broad, while the leaves shown on the specimen photographed at Kew measure as much as 22.5 cm long by 8.5 cm broad. In the collection of Maguire, Wurdack, d- Bunting 36640 from the Rio Pacimoni (a tributary of the Rio Casiquiare, whence the type locality) and of Williams 14076, the leaf-blades are 18-26 cm long and 8-11.5 cm wide and u p to 21 cm long and 7.5 cm wide respectively, thus approaching closely the limits given in Spruce's original collection.
The matter of 3-verticillate leaves, as given in the original description, but questioned at the time as being constant, is found to vary to 4-verticillate. The Maguire, Wurdack, & Bunting 36640 specimen, referred to above, has 4-verticillate leaves. Most of the collections examined, however, show 3-verticillate leaves. At the time of Spruce's original description, no fruit was extant. However, based upon two present collections, considered as conspecific with H . nitida, the following emendation m a y be given: capsula lignosa magna transverse oblonga vel suborbiculari-quadrata complanata extus purpureo-nigra superficies cinerea supra medium cicatrice calycis circumdata 9-10 cm lata 8-9.5 cm alta, valvulis ad margines 3-3.5 mm crassis medio ad 7 mm crassis; seminibus magnis compressissimis late oblongis extremitatibus rotundatis 5.5 cm longis 3.2 cm altis vel latis.