Ehyncanthera intermedia Ule, Notizbl. Bot. Gart. Berlin 6: 348. 1915.
Bhyncanthera orinocensis Sprague, Trans. Proc. Bot. Soc. Edinb. 22: 431. 1904.
Gleason (Brittonia 1: 134. 1932.) pointed out the variability in cauline
pubescence to be found in the British Guiana specimens of R. grandiflora. Collections
since 1932 have obscured the lines between the "well-marked" forms
noted by Gleason. Both Ule's and Sprague's collections (as represented at Kew)
are so similar as to appear parts of the same collection number; both have longpilose
stems. As suggested by Gleason, R. acuminata Benth. and R. betulifolia
Cogn., upon comparison with presently available collections, will probably follow
R. intermedia and R. orinocensis into synonymy.
R. grandiflora is perhaps the commonest shrub in the Venezuelan morichales
and is also frequent in moist areas along roadsides in the llanos. Plants may be
found in flower at any time of the year, depending on the seasonal wetness of
the habitat. Successive rings of plants flower around a morichal as the water
level lowers during the dry season; each plant, as the water level drops, gradually
defoliates and ceases flowering. Robust colonies grow in almost soilless but
seasonally moist depressions on the crystalline lajas at Puerto Ayaeucho.
As delimited in the past, the genus Potcranthera has been composed of three
discordant elements; the species of sect. Onoctonia are congruous with Acisanthera.
the generotype seems to belong in the TiboucJiineac as a monotypic genus
related to Acisanthera, and the remaining species are well placed in the genus
Siphanthera. These adjustments will be treated in detail in a future paper,
only one transfer being made at present to accommodate the discussion of a new
Venezuelan species of Siphanthera.