1. Nutlet surface dimpled to rugulose, lacking tubercles ... J. punensis
1. Nutlet surface tuberculate
2. Nutlet margin sharply angled, smooth, lineate-rimmed, or narrowly winged
3. Nutlets homomorphic, all similar in size and sculpturing (rarely slightly heteromorphic by size in J. costata and J. diplotricha)
4. Nutlet margins smooth or lineate-rimmed
5. Nutlet margins appearing beaded by periodic thickenings ... J. gypsites
5. Nutlet margins smooth, not beaded
6. Nutlets strongly incurved-arched, 0.8–1.2 mm long ... J. pusilla
6. Nutlets straight, not incurved-arched, 1.5–2 mm long ... J. diplotricha
4. Nutlets margins narrowly winged to winged
7. Inflorescence bracts lanceolate, long-acuminate; pedicels 0–0.5 mm in fruit; calyx 4–6 mm in fruit; nutlets 1.2–1.8(2) mm, margins very narrowly winged,
wing less than 0.1 mm wide wing ... J. costata
7. Inflorescence bracts, when present, linear-oblong; pedicels 1–1.5 mm in fruit; calyx 2.5–3.5 mm in fruit; nutlets (1.5)1.8–2.5 mm, margins winged,
wing greater than 0.2 mm wide ... J. holoptera
3. Nutlets heteromorphic by size, one larger than the other three
8. Pedicels very short, < 1 mm long, often scarcely evident; corolla limb <1 mm diam; fruiting calyces 1.5–2 mm long; odd nutlet 0.7–1 mm long,
consimilar nutlets 0.6–0.8 mm long
9. Stems strigose only; odd nutlet 0.7 mm long, consimilar nutlets 0.6 mm long ... J. angelica
9. Stems strigose and hispid; odd nutlet ca. 1 mm long, consimilar nutlets 0.6–0.8 mm long ... J. parviflora
8. Pedicels 0.5–4(6) mm; corolla limb 1-4 mm diam; fruiting calyces 2.5–4 mm long; odd nutlet 1–2 mm long; consimilar nutlets 0.8–1.5 mm long
10. Pedicel 1–4(6) mm, outer fruiting calyx trichomes whitish, stout-hispid, mostly horizontal, up to ca. 2 mm long ... J. racemosa
10. Pedicel 0.5–2 mm, outer fruiting calyx trichomes whitish, mostly narrow-hispid, ascending to descending, up to ca. 1.5 mm long
11. Plant often appearing as a woody shrub, 1–10 dm tall; shoots markedly fastigiate, relatively straight and parallel; lower leaves up to 10 cm long; corolla limb 2.5–3 mm diam;
pedicels 1–2 mm long; fruiting calyx ca. 3 mm long; odd nutlet 1.5–2 mm long, consimilar 1–1.5 mm long ... J. fastigiata
11. Plant a slender, annual herb, 1-3 dm tall; shoots not markedly fastigiate, more highly branched; lower leaves 2–4 cm long; corolla limb 1.5–4 mm diam;
pedicels 0.5–1.5 mm long; fruiting calyx 2.5–4 mm long; odd nutlet ca. 1.7 mm long, consimilar ca. 1.3 mm long ... J. inaequata
2. Nutlet margins rounded (rarely +/- sharply angled in J. angustifolia)
12. Nutlets heteromorphic (rarely homomorphic) ... J. angustifolia
12. Nutlets homomorphic
13. Flowers bracteate; nutlets 0.7–1.5 mm long; length of attachment scar areole >0.5 nutlet length
14. Stem hairs spreading only; corolla tube 2.0 mm long ... J. geohintonii
14. Stem hairs appressed and spreading; corolla tube 2.0–3.0 mm long
15. Nutlet tubercles conical, pointed, longer than wide ... J. sheylae
15. Nutlet tubercles rounded, low, about as long as wide
16. Calyces 2–3 mm long, hairs ascending hirsute, <1 mm; nutlets 1–1.5 mm long; plants flowering in summer ... J. albida
16. Calyces 3–4 mm long, hairs spreading hispid, 1–1.5 mm; plants flowering in spring ... J. mexicana
13. Flowers ebracteate; nutlets 0.5–0.7 mm long, length of attachment scar areole <0.5 nutlet length ... J. grayi
17. Stems just below cymules with appressed and spreading-hispid trichomes; basal fruits along cymule axis apart, not touching one another; corollas inconspicuous, limb 0.5-1 mm wide ... J. grayi var. cryptochaeta
17. Stems just below cymules with predominantly appressed trichomes, few if any spreading-hispid; fruits along cymule axis close together, touching one another; corolla limb 0.5-3 mm wide
18. Nutlets tuberculate, often densely so, but with at least some tubercles on inner side or margin; corollas conspicuous, limb 2–3 mm wide ... J. grayi var. grayi
18. Nutlets not tuberculate, smooth on all surfaces; corollas inconspicuous, limb 0.5–1 mm wide ... J. grayi var. nesiotica