Calendula Linnaeus (1753: 921)

Simão, Inês, Reyes-Betancort, J. Alfredo, Talhinhas, Pedro, Morais-Cecílio, Leonor & Silveira, Paulo, 2024, Taxonomic revision of the genus Calendula (Asteraceae) in the Canary Islands, Phytotaxa 640 (2), pp. 125-160 : 136

Calendula Linnaeus (1753: 921) .

Lectotype (designated by Green in Hitchcock & Green 1929: 183): Calendula officinalis L.

Annual or perennial herbs covered with glandular and non-glandular hairs in different proportions. Stems (7.5) 20.7– 36.15 (146) cm prostrate, ascending, diffuse or erect, branched, frequently glandular and aromatic. Leaves (22.9) 41–65.4 (135) × (3.4) 6.5–12 (47) mm, (0.1) 0.16–0.26 (0.5) mm thick, alternate, simple, uninervate, varying from spatulate to sub-spatulate, obovate, oblanceolate, oblong or linear, with margins entire, repand, undulate to dentate; base attenuate, truncate or auriculate; apex acute to obtuse; upper leaves usually similar in shape to the basal ones but progressively smaller towards the apex, many times sessile and auriculate. Capitula (0.65) 1–2.3 (6.7) cm, solitary, heterogamous and radiate. Involucre (3.3) 4.9–7.7 (14.3) mm, with 1–2 rows of linear or acuminate bracts, apex acute, and a narrow scarious margin. Ray florets (8) 13–19 (45), (4.4) 7–13.2 (29.4) mm, ligulate, female and fertile, with a yellow or orange corolla, hairy at the base and 3-lobed at the apex. Disc florets 13–50, over 50 in C. officinalis , (2.4) 2.75–3.7 (4.7) mm, functionally male, with a yellow to orange, sometimes brown or violet-purple tubular corolla, 5-lobed. Anthers (1) 1.15–1.97 (2.37) mm, sagittate-caudate, with free filaments. Styles (1.5) 1.9–3.2 (4.3) mm. Receptacle flat, without palea. Outer achenes rostrate (4.7) 7.7–12.8 (24.9) × (0.9) 1.9–2.98 (5.1) mm, straight to deeply curved, often with developed dorsal spines, sometimes bialate (4.1) 6.3–7.7 (10.4) × (1.5) 6.1–7.9 (9.3) mm, trialate (5.7) 7.7–9 (11.5) × (5.2) 7.1–8.6 (11.1) mm or sub-rostrate (1.48) 4.2–5.3 (6.4) × (0.7) 1.2–1.7 (2.9) mm; middle achenes cymbiform (3.7) 4.8–6.9 (10.1) × (2.1) 3.2–5.9 (8.9) mm, less usually bialate or trialate, sometimes with dorsal wings or spines; inner achenes vermiculate exalate (2.7) 3.4–4.1 (6.1) × (0.67) 1.2–1.6 (2.36) mm or with 2 lateral wings (2.9) 3.7–4.6 (7) × (0.93) 1.94–2.7 (4.7) mm, many times both, circular, hook-shaped or falcate. Pappus absent.