LEGUMINOS #-MIMOSE 2. 49 
including about eleven hundred species, presents so many constant 
characters that to subdivide it we must fall back upon features 
which are elsewhere deemed of wholly secondary value. Thus we 
have seen that the genera are mainly based on the form and de- 
hiscence of the fruits and the relations of the endocarp to the seeds, 
and the degree of complexity of the leaves, which are either simply 
pinnate or bipinnate. The series or tribes are based on the pra- 
floration of the calyx, the number of stamens, and the presence or 
absence of a sort of glandular prominence on top of their connectives. 
Hence we get the four following series, which alone do we retain :— 
I. Avenanturrr2£.—Calyx valvate; androceum diplostemonous ; 
stamens free, usually’ tipped by a gland. 
II. Evumimosrz.—Calyx valvate; androceum isostemonous or 
diplostemonous ; stamens free, without apical: glands. 
III. Parxiex—Calyx imbricate; androceum diplostemonous or 
pleiostemonous, with only five fertile stamens ; apical glands present 
or absent. 
IV. Acactza.—Calyx valvate; stamens indefinite, free, mona- 
delphous or polyadelphous.’ 
The Mimosee are plants from warm climates, abounding in the 
tropical and subtropical zones of both hemispheres, and hardly 
extending more than forty degrees on either side of the Equator. Of 
the twenty-eight genera retained by us, five alone are peculiar to 
America, viz., Plathymenia, Stryphnodendron, Lysiloma, Enterolobium, 
and Affonsea; and eight to the Old World—viz., Pentaclethra, Hle- 
phantorrhiza, Gagnebina, Tetrapleura, Xerocladia, Serianthes, Xylia 
and <Archidendron. Of these last the five former have only been 
observed in tropical Africa or Madagascar ; the three latter in Asia 
or Oceania. Archidendron, a monotypical genus, is only Australian ; 
but the genera found in nearly every warm climate are very unevenly 
distributed asa rule. Thus, Mimosa, Calliandra, Pithecolobium, and 
Acacia have species in all the countries of the world, but Calliandra, 
out of eighty species, has only one in the Old World. Those of 
1 This gland is almost entirely absent in one ? The freedom or union of the staminal fila- 
section of the genus Prosopis. In Xyliait may ments is used by Benruam to distinguish two 
disappear so early that until now its presence series, Acaciee and Ingea, which we are unable 
has not been recognised. to separate for the reasons given above (pp. 41, 42). 
VOL. II. E 
