Calendula arvensis Linnaeus (1763: 1303)

Gonçalves, Ana Carla, Ouhammoud, Ahmed, Amirouche, Rachid, Santos, Conceição, Figueiredo, Estrela & Silveira, Paulo, 2023, A taxonomic revision of Calendula (Asteraceae) in Morocco, including some taxa from Algeria and Tunisia, Phytotaxa 605 (1), pp. 1-83 : 26

1. Calendula arvensis Linnaeus (1763: 1303) ; Desfontaines (1799: 306); Battandier (1888: 478); Bonnet & Barrette (1896: 509); Pitard (1913: 58); Pampanini (1931: 452); Jahandiez & Maire (1934: 788); Quézel & Santa (1963: 967); Heyn et al. (1974: 180); Meikle (1976: 206); Jeffrey (1979: 326); Pottier-Alapetite (1981: 1022); Alavi (1983: 193); Valdés et al. (1987: 78); Valdés et al. (2002: 671); Boulos (2002: 266); Ibn Tattou & Fennane (2009: 27); Dobignard & Chatelain (2011: 185); Gonçalves et al. (2014: 270). Type:—EUROPE. ‘In Europae arvis’, L̂fling s.n. in Herb. Linnaeus 1035.1 (lectotype LINN!, designated by Heyn et al. (1974: 182)).

Description:––Annual herbs. Stems (2) 17.3–45.5 (80) cm long, ascending to erect, sometimes decumbent, branched at the base, with glandular and non-glandular hairs, in varying proportions, ± viscous. Basal leaves (1.2) 2.4–4.8 (6.5) × (0.2) 0.4–0.8 (1.1) cm, (0.3) 0.3–0.5 (0.5) mm thick, oblanceolate, acute or obtuse, margin sub-entire to sinuate-dentate, base attenuated in a petiole, with glandular and non-glandular hairs; the middle and upper cauline leaves progressively smaller towards the apex, oblanceolate to lanceolate, sessile, usually auriculate. Capitula solitary, (1) 1.2–1.4 (2) cm in diameter. Outer achenes rostrate (5) 7.1–11.7 (15.2) × (0.8) 1.3–1.9 (2.7) mm, usually strongly curved and with long spines at the back, usually with two small teeth, one at the base and another at the apex, sometimes bialate (8.3) 10.8–12.4 (13.3) × (7.2) 7.7–9.3 (10.2) mm, with two wings, with irregularly incise margins, extended along both sides up to the apex; middle achenes cymbiform (4.8) 6.7–8 (8.5) × (3.8) 5.3–7 (8) mm, sometimes lacking; inner achenes vermicular-alate (3.5) 3.8–5.2 (5.8) × (2) 2.7–3.3 (3.7) mm, hook-shaped to circular, with two narrow lateral wings, and/or vermicular-exalate (3.2) 3.7–4.5 (5.3) × (1.2) 1.2–1.7 (1.8) mm, circular. Figures 18 and 31E .

Habitat and distribution:—Widespread throughout the North Africa ( Morocco, Algeria, Tunisia, Lybia, Egypt) on waste grounds, cultivated fields and grasslands or on the margin of roads and ditches, up to elevations of 1300 m. Also native in Central and South Europe, SW Asia and Macaronesia. Introduced in other parts of the globe such as Australia and California. Figure 15 .

Conservation status:—Least Concern (LC). This is a widespread species in the study area, and in the circum- Mediterranean region, including Central Europe and the Middle East. It inhabits ruderal and waste grounds and faces no major threat.

Chromosome number:— 2n = 44.

Genome size:—5.23 ± 0.29 pg.

Figures

FIGURE 15. Geographic distribution of Calendula arvensis, C. stellata, and C. tripterocarpa in Morocco.

FIGURE 18. Variability of achene morphology of Calendula. A. C. suffruticosa subsp. monardii (Silveira, Gonçalves &Amirouche 3316, AVE); B. C. suffruticosa subsp. foliosa (Silveira, Gonçalves & Amirouche 3320, AVE); C. C. suffruticosa subsp. djurdjurensis (Silveira, Gonçalves & Amirouche 3321, AVE); D. C. suffruticosa subsp. tunetana (Silveira 3039d, AVE); E. C. suffruticosa subsp. suffruticosa (Silveira 3038, AVE); F. C. arvensis (S. Castro P35 in Silveira 3078, AVE). Rostrate achenes: A1, 2; B1-3; C1, 2; D1-4; E1, 2; F1, 2. Bialate achenes: B4-6. Trialate achenes:A3, 4; C3-5; D5, 6. Cymbiform achenes: E3-5; F3, 4. Vermicular-alate achenes: A5; D7; E6; F5. Vermiculate-exalate achenes: A6, B7, 8; C6, 7; D8; E7 and F6. All achenes in side view, except: A3, B4, B5, C4, D5, E3, E5 and F3 in ventral face view, and B6, C3, C5, D6, E4 and F4 in ± dorsal face view. Scale bars = 1 cm.

FIGURE 31. A–D. Calendula suffruticosa subsp. suffruticosa (Silveira 3038, AVE). A. Habit; B. fruiting capitulum; C. flowering capitulum; D. detail of leaves. E. C. arvensis (Silveira 3129, AVE), small-sized form.