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. Stem woody at base, appearing perennial; pedicel 1–4(6) mm, lower calyx with stout, divergent, white bristle-like hairs ... J. racemosa
10. Stem not woody at base, herbaceous; pedicel 0.5–2 mm, calyx without stout, divergent, white bristle-like hairs
11. Shoots markedly fastigiate; lower leaves 1-3 mm wide, to 10 cm long; corolla limb 2.5–3 mm diam; pedicels 1-2 mm long; odd nutlet 1.5–2 mm long,
consimilar 1–1.5 mm long ... J. fastigiata
11. Shoots not markedly fastigiate; lower leaves linear to oblanceolate, 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 1.7 mm long, consimilar 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 with appressed-strigose and spreading-hispidulous trichomes ... J. grayi var. cryptochaeta
17. Stems with appressed-strigose trichomes only
18. Corolla conspicuous, limb generally 2–3 mm wide; nutlets abundantly tuberculate ... J. grayi var. grayi
18. Corolla inconspicuous, 0.5-1 mm wide; nutlets sparsely tuberculate to glabrous ... J. grayi var. nesiotica