Stevia

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

Grashoff, J. L. 1972. A Systematic Study of the North and Central American Species of Stevia. Ph.D. dissertation. University of Texas.

Lower Taxa

Stevia lemmonii, Stevia micrantha, Stevia ovata, Stevia plummerae, Stevia salicifolia, Stevia serrata, Stevia viscida

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