Type species: Revesia chilensis Gay. 
Four species in northern Chile (one of which also extending 
into adjoining Argentinian territory), usually at rather high alti- 
tudes in the Andes (2500-3500 m), except R. chilensis, which 
occurs at lower elevations (100-800 m) near the Pacific Coast. 
Although the plants are apparently similar in habit to those of 
Leptoglossis, Revesia is a more advanced genus, because in addi- 
tion to a number of differentiating characters mentioned in the 
key, it shows a more developed zygomorphic corolla and an 
androecium composed of four didynamous elements (these are 
the two posterior stamens with shorter filaments, and the two 
lateral ones with longer filaments; the anterior stamen is missing). 
Moreover, these lateral stamens may be either functional. as is the 
case In R. chilensis, or they may become sterile staminodes in 
more advanced species (for example: R. parviflora). Another 
peculiarity of R. chilensis is shown by the anthers of the shorter 
posterior pair of stamens: the thecae are unequal and divergent, 
whereas the ones of the longer pair are more parallel and equal- 
sized. 
Diagnostic features at the species level.—The multicellular 
glandular hairs of the calyx may be either oblong (R. chilensis and 
R. cactorum), or globose (R. parviflora and R. juniperioides). 
The stamens are usually glabrous, except in R. parviflora which 
has piliferous filaments; this latter character is correlated with the 
aggregation of pollen grains, which are united in tetrads in R. 
parviflora, and free in the other three species. The size of the 
corolla is another useful character. 
KEY TO THE SPECIES 
1. Capitate hairs of the calyx with an oblong head. Filaments glabrous; 
pollen grains free. 
2. Corolla 6-8 mm long.................cccceeeee 1. R. chilensis 
2’. Corolla (10) 11-12 (15) mm long .............. 2. R. cactorum 
I’. Capitate hairs of the calyx with a globose head. Corolla 8-10 mm long. 
2. Filaments piliferous; pollen grains in tetrads. Stems comparatively 
delicate, with long internodes ................. 3. R. parviflora 
2’. Filaments glabrous; pollen grains free. Stems robust. rigid, intri- 
cately-branched, with short internodes......... 4. R. juniperoides 
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