Stevia
Icon. 4: 32, plates 354, 355. 1797.
Annuals, perennials, subshrubs, or shrubs, 50–120+ cm. Stems erect, usually branched. Leaves cauline; all or mostly opposite or mostly alternate; petiolate or sessile; blades 1- or 3-nerved, deltate, lanceolate, lance-elliptic, lance-linear, elliptic-oblong, linear, ovate, or trullate, margins entire or serrate, serrulate, or toothed, faces hirtellous, puberulent, glabrescent, or glabrous (sometimes shiny), sometimes gland-dotted. Heads discoid, in loose to dense, corymbiform arrays. Involucres ± cylindric, (1–)2–3 mm diam. Phyllaries persistent, 5(–6) in ± 1 series, 2–3-nerved, ovate or oblong to lanceolate or linear, ± equal (herbaceous). Receptacles flat or convex, epaleate. Florets 5(–6); corollas purple to pink or white, throats narrowly funnelform (lengths 3–4 times diams., ± hirtellous inside); styles: bases sometimes enlarged, glabrous (sometimes papillose), branches filiform. Cypselae columnar to prismatic or fusiform, 5-ribbed, gland-dotted and/or scabrellous; pappi (sometimes ± vestigial on 1–2 cypselae of each head) persistent, of 5, (distinct or connate) muticous scales plus 0–5[–30+] subulate-aristate to setiform scales or bristles. x = 11, 12, 17.
Distribution
w United States, Mexico, Central America, South America.
Discussion
Species ca. 240 (7 in the flora).
Selected References
None.
Lower Taxa
Key
| 1 | Annuals | Stevia micrantha |
| 1 | Perennials, subshrubs, or shrubs. | > 2 |
| 2 | Subshrubs or shrubs | > 3 |
| 2 | Perennials | > 4 |
| 3 | Phyllaries densely stipitate-glandular and sparsely villous to hispid; corolla lobeshispidulous | Stevia lemmonii |
| 3 | Phyllaries glabrous, usually viscid-shiny (from resinous exudate of ± evident sunken glands), not villous or hispid; corolla lobes glabrous | Stevia salicifolia |
| 4 | Leaves mostly opposite, blades lanceolate, lance-ovate, oblanceolate, ovate, or trullate; phyllary apices rounded to blunt or obtuse; pappi usually shorter than corollas (sometimes coroniform) | > 5 |
| 4 | Leaves mostly alternate (often with abundant axillary clusters of smaller leaves), blades lance-linear, linear, linear-oblong, narrowly oblanceolate, or oblong; phyllary apices acute to acuminate; pappi usually equaling corollas (sometimes coroniform or 0) | > 6 |
| 5 | Leaves petiolate (raised venation usually including only midvein and primary laterals); involucres 4–5.5(–6) mm | Stevia ovata |
| 5 | Leaves sessile or nearly so (raised venation reticulate, including secondary andtertiary veins); involucres (5.5–)6–8.5 mm | Stevia plummerae |
| 6 | Heads in ± congested, compact clusters; peduncles 0 or 1–4 mm; involucres 5–6(–7)mm; phyllaries sessile-glandular, sparsely villosulous | Stevia serrata |
| 6 | Heads borne in open, subcorymbiform arrays; peduncles mostly 5–30 mm; involucres 6–8 mm; phyllaries sessile- and stipitate-glandular (not villous) | Stevia viscida |