283 
e 
DIDYMOCARPI. 30. 
Pods didymous, or with sides distorted or corru- 
gated, or in A. Breweri oblong-ovate and long-beaked 
and sulcate only below, 3-5 mm. long (about 7 mm. long 
in A. Breweri), from ovate to broader than long, mostly 
corrugated transversely, rather coriaceous, not or but lit- 
tle inflated, evidently stipitate only in A. Brazoensis, cor- 
date at base, 2-celled. Flowers about sessile in dense 
(loose in A. reflexus) heads, sometimes elongating to 
spikes in fruit, minute or small, rarely 8 mm. long. Calyx 
long-villous. Leaflets never acute, small, mostly notched, 
not over 8 pairs. Stipules not connate. Weak, low and 
slender annuals (possibly perennials in A. diphacus and 
Angelinus). Tropical plants growing on prairies and 
plains. 
KEY. 
A. Pods straight, evidently longer than calyx, sharp, or triangular 
at tip, much obcompressed, broadly bisulcate ventrally, at least 
as long as wide or longer, closely reflexed in short and narrow 
spikes, with the lower edges incurved on the sides and with ven- 
tral suture sharp and raised, with the tip rather arcuate, 
strongly cross-ribbed around the margins, deeply sulcate dor- 
sally, much distorted and with cross-section nearly that of the 
letter A without the bar, appearing as if minutely stipitate. 
Peduncles filiform, axillary. Leaflets notched, not over 5 
pairs. Stems filiform, widely spreading and much branched. 
Pods 7 mm. long, oblong-ovate. 266 reflexus. 
Pods 3-4 mm. long and wide, not oblong-ovate. 267 nigrescens. 
SA. Pods 7 mm. long and with conical beak nearly as much more, 
erect in heads, round to reniform in cross section, not corru- 
gated. Flowers about 7-8 mm. long. Low annuals. 
Pods long-beaked. 268 Breweri 
3A. Pods about as broad as long or broader, very obtuse and: 
rounded at both ends, apiculate, didymous, or half-oblate-oval. 
3AB. Pods scarcely longer than the calyx, about 3 mm. long, 
coarsely and strongly cross-corrugated, sessile, erect in dense 
i heads, about oval, not ob p ed, not inflated. Flowers 
I 3-8 mm. long, many, white or purple, with the same tendency 
i to become rudimentary as in A. nigrescens. Weak annuals. 
i Pods 3 mm. long, with cross-section a crescent. 269 didymocarpus. 
Pods 3-3 mm. long, with cross-section flatly tripuetrous-cordate. 
"n 
