240 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
Among these 9 species distributed between Darién (Panama) and 
central Mexico, one, C. sambuense, is distinguished by large, orange 
red flowers, a sparsely branched inflorescence, and very broad leaves. 
At first sight, it may be easily confused with C. coccineum (Aubl.) 
Engl. & Diels, which grows in the same region. 
In Combretum superbum we have another feature which affords 
ground for immediately sorting it out of the general collection: the 
panicles present several opposite branchlets, which in their turn bear 
from 2 to 5 pairs of opposite spikes. This I call a twice-branched 
panicle; in all the other species considered here the floral spikes issue 
directly from the main axis. This arrangement of the inflorescence, 
as noted in C’. superbum, occurs in other American species belonging 
to distinct sections, as for instance in C. leprosum, in C. mellifiuum - 
the branching is carried even further. But it is a good distinctive 
character in so far as the Central American species are concerned. 
The 7 remaining species are founded primarily on the variations 
in the shape and the indument of the petals, and secondarily on char- 
acters derived from the calyx and leaves. The fruits also seem to 
vary in size and indument according to the species, but they are 
seldom present in the specimens at hand. 
As to shape there are 3 types of petals. In C. farinosum they are 
distinctly oblong-spatulate, very narrow in proportion to their 
length, and with a long claw; whereas they are sessile in all other 
species, being ovate and decidedly shorter than the calyx lobes in 
some cases, almost orbicular and mostly equaling the calyx lobes in 
other instances. 
Combretum phaenopetalum, C. polystachyum, and C. argenteum 
are the species with ovate petals, the first differing from the two 
latter in the less degree of hairiness of the calyx inside and of the 
disc margin, and in the extreme length of the style. A very long 
panicle with 6 to 8 pairs of opposite spikes, glabrous petals, and a 
calyx sparsely villous within, distinguish C. polystachyum from 
C. argenteum, which has pilosulous petals, a character not found in 
other species of the section. 
The group with orbicular petals includes (. erianthum Benth., 
originally described from specimens collected by Hartweg at Retal- 
huleu, Guatemala, and probably confused by Eichler? with a Bra- 
zilian species growing near Rio de Janeiro. It is characterized by 
having the calyx densely villous-tomentose without, and is possibly 
the species referred to by Eichler as C. warscewiczianum. The two 
remaining species, C. benthamianum and C. lepidopetalum, differ 
from C. erianthum in having their calyx densely covered with whit- 
ish or brownish scales. In C. benthamianum the petals are glabrous, 
*In Mart. Fl. Bras, 147: 108. 1867. 7 Op. cit. 110. 
