Gordon C. Tucker in Flora of North America (vol. 7)
Herbs, shrubs, or subshrubs,
annual or perennial.
sparsely branched laterally; puberulent, glabrous, or glabrate (scabrid when dry).
stipules minute tufts of filiform hairs; petiole without pulvinus (equal to or longer than leaflets); leaflets (1 or) 3, (conduplicate).
terminal, racemes (dense); bracts usually absent; (pedicels 3-5 mm, glabrous).
zygomorphic; sepals usually persistent (eventually deciduous), distinct, equal; petals slightly unequal (in pairs); stamens 6 (well-exserted, ± equal); filaments inserted on gynophore, glabrous; anthers (oblong), coiling after dehiscence; gynophore reflexed in fruit; (pistil 2-lobed basally, style filiform, eventually spinelike).
schizocarps, indehiscent, obovate, (reticulate, ± tuberculate, valves disarticulating from persistent, round septum).
2(-4), globose, not arillate.
Species within checklist:
Petrified Forest National Park