Zinnia L.
Zinnia is a New World genus of ca. 17 species, mostly concentrated in Mexico (but extending south to Argentina and north to the southern United States). Several species are cultivated as ornamentals but only a few are more or less widely cultivated, perhaps mostly Zinnia violacea or hybrids of it (see Tebbitt & Knees 2000 and Jäger & al. 2008).
- Leaves linear to linear-lanceolate, 5-8 mm wide. Cypselae of disc flowers with 1 awn. Disc flowers blackish-purple, ray flowers usually bright orange (but sometimes otherwise coloured in cultivars). Receptacular scales (sub-) entire at apex === 1. Zinnia angustifolia
- Leaves lanceolate, ovate or oblong, 25-35 mm wide. All cypselae unawned. Disc flowers yellow, ray flowers usually red (but sometimes white, purple or yellow in cultivars). Receptacular scales with fimbriate apex === 2. Z. violacea
Literature
Delvosalle L. (1953) Quelques adventices nouvelles pour la Belgique. Bull. Soc. Roy. Bot. Belg. 85: 297-303.
Jäger E.J., Ebel F., Hanelt P. & Müller G. (eds.) (2008) Rothmaler Band 5. Exkursionsflora von Deutschland. Krautige Zier- und Nutzpflanzen. Springer Verlag, Berlin: 880 p.
Smith A.R. (2006) Zinnia. In: Flora of North America Editorial Committee (eds.), Flora of North America, vol. 21. Oxford University Press, New York-Oxford: 71-74.
Tebbitt M.C. & Knees S.G. (2000) Zinnia. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: 649-650.
Torres A.M. (1963) Taxonomy of Zinnia. Brittonia 15: 1-25.
Turner B.L. (2016) The Comps of Mexico. A Systematic Account of the Family Asteraceae. Chapter 21. Subtribe Zaluzaniinae: Hybridella, Zaluzania; Subtribe Zinneenae: Heliopsis, Philactis, Sanvitalia, Tehuana, Trichocoryne, Zinnia. Phytologia Memoirs 25: 114 p.