Nov., 1923] 
RYDBERG — NORTH AMERICAN FABACEAE 
487 
World and America, in which the pod is flat and 2-celled. In Atelephragma 
Rydb., another segregate found only in America, the septum is incomplete, 
while in Homalobus and Kentrophyta, both exclusively American, there is 
not a vestige of a partition and the fruit is exactly like the fruit of Poitoea, 
Coursetia, or Corynella, placed in the Robinieae. 
Both Bentham and Hooker, and Taubert seem to have ignored or else 
knew imperfectly these segregates of Astragalus when characterizing their 
subtribes. In Benthamantha, also placed in the latter subtribe, the pod is 
also similar but with false transversal partitions. In Sesban and Dauben- 
tonia, both referred to Robinieae, the pod is hardly compressed, in the 
former terete or nearly so, in the latter 4-angled. There is therefore no 
definite line between these three subtribes as constituted by Bentham and 
Hooker and by Taubert, nor are the Brongniartiae or the Tephrosieae 
very distinct. 
The classification must therefore be remodeled along other lines. I 
shall give here a tentative reclassification, which will probably be modified 
when more study has been made on the Astragalinae. 
Seeds strophiolate; embryo with a straight radicle; 
flowers 1 or 2 in the axils of the leaves or in terminal 
racemes or panicles; calyx subtended by a pair of 
deciduous bractlets; pods flat; trees or shrubs. 
Seeds not strophiolate (rarely slightly so in species of 
Gracca); embryo mostly with an incurved radicle; 
flowers mostly racemose. 
Bractlets 2 under the calyx; pods internally with 
more or less distinct false cross-partitions. 
Calyx tubular, with long lobes; petals long- 
clawed, their blades cuneate at the base, that 
of the banner oblong, not spreading; pods flat, 
many-seeded, dehiscent; shrubs with odd- 
pinnate leaves. 
Calyx campanulate, with short tooth-like lobes; 
petals short-clawed, at least the blades of 
the wings with basal auricles; blade of the 
banner sub-orbicular or broadly ovate; 
pods not flattened or if flat 2-seeded 
(Glottidium). 
Exocarp of the pod not inflated; hypanthium 
obsolete, not differentiated from the calyx; 
shrubs or trees, with abruptly pinnate 
leaves. 
Exocarp of the pod inflated, forming two 
elongate bladders, one on each side of the 
pod; hypanthium well developed and dif¬ 
ferentiated from the calyx, obconic; shrubs 
and trees, with odd-pinnate leaves. 
Bractlets under the calyx wanting; pods usually 
without cross-partitions, except in Bentha¬ 
mantha, Sphinctospermum, and Hebestigma. 
Subtribe 3. Brongniartianae. 
Subtribe 4. Barbierianae. 
Subtribe 5. Sesbanianae. 
Subtribe 6. Diphysanae. 
