196 NOTES ON MIMOSE. 
some with a nearly straight fruit. Pithecolobium would thus 
include all monadelphous Mimosee with indefinite stamens, 
bipinnate leaves, and fleshy or pulpy pods, excepting those 
few species which I have followed Martius in referring to a 
distinct genus, under the name of Enterolobium. 
The distinction thus formed between Pithecolobium and 
Inga, rests, it is true, chiefly upon the foliage, which is 
always simply pinnate in Inga and Affonsea, and bipinnate in 
Pithecolobium, although the number of pinne and leaflets be 
sometimes reduced to a single pair of each, and even, in one 
instance, to a single foliole on each pinna. This peculiarity 
of foliage is, however, of considerable importance in Legu- 
minose, and moreover, the fruit of the true Ingas is generally 
much thicker and more fleshy, never twisted, and always 
has a remarkably thick margin. Pithecolobium is more de- 
cidedly distinguished by the pod from Albizzia and Callian- 
dra, but is not always so readily known from them when in 
flower. All the species have glandular petioles, which are 
scarcely ever to be seen in Calliandra, and may generally 
serve as a mark for the American sections; and amongst the 
Asiatic sections, Concordia may be known from Albizzia by 
the spines, and Clypearia by the peculiar inflorescence. Tt is 
only the few species of Cathormion that may be doubtful in 
the absence of fruit. The small flowers of Unguis-Cati, the 
spinescent stipules of Unguis-Cati and Concordia, the inflo- 
rescence of Caulanthon and the tubular flowers of Caulanthon 
and Chloroleucon are also very different from what is observ- 
able either in Albizzia or Calliandra. 
As the groups into which the genus may be divided are 
much more distinct from each other than those which I have 
adopted in Acacia and Calliandra, and may be considered as 
so many distinct genera, I have described them as sub- 
stantive sections, of which the following are the principal 
characters. 
I. Uneuis-Carti.—Stipule nonulle v. omnes spines- - ; 
centes. Pinnae l-rarius 2-juge. Foliola 1-3-juga. Legu- 
men lineare, tortum.—Species 1-13, omnes Americana. 
