Calendula L.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1976, Flora Europaea. Volume 4. Plantaginaceae to Compositae (and Rubiaceae), Cambridge University Press : 206

100. Calendula L. 3

Annual or perennial herbs, sometimes woody at the base, often glandular and aromatic. Leaves alternate, simple. Inflorescence sometimes branched. Involucral bracts in 1-2 rows, linear, acuminate, subequal, with a narrow scarious margin. Receptacle flat, without scales. Capitula medium. Outer florets ligulate, yellow or orange, female, fertile. Inner florets tubular, yellow, orange, brown or violet-purple, functionally male. Anthers sagittate-caudate; filaments free. Outer achenes with a narrow beak, sometimes cymbiform, or 3-winged; inner smaller, strongly falcate or almost annular, tuberculate-rugose on dorsal surface, usually unwinged; pappus absent.

Literature: D. Lanza, Monografia del Genere Calendula L. Palermo. 1919 ; Atti Accad. Sci. Palermo ser. 3,12: 1-166 (1923). H. Meusel & H. Ohle, Österr. Bot. Zeitschr. 113: 191-210 (1966). H. Ohle, Feddes Repert. 85: 245-283 (1974).

1 Ligules usually less than twice as long as involucral bracts

2 Outer achenes with a narrow beak or cymbiform, not 3-winged 4. arvensis

2 Outer achenes without a beak, broadly 3-winged 5. tripterocarpa

1 Ligules usually twice as long as involucral bracts

3 Perennial, sometimes woody; florets normally concolorous;

outer (beaked) achenes often conspicuously long, patent or weakly incurved 1. suffruticosa 3 Usually annual; stems herbaceous or woody only at the base 4 Ligules yellow or orange; tubular florets yellow, orange or brownish; outer achenes usually strongly incurved

2. officinalis

4 Ligules violet at apex; tubular florets violet-purple; outer achenes patent 3. stellata