Calendula murbeckii Lanza ex Murbeck (1923: 59)

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 : 33-34

7. Calendula murbeckii Lanza ex Murbeck (1923: 59) ; Maire (1928b: 56); Emberger & Maire (1941: 1152); Nègre (1958: 5, 1962: 299); Ibn Tattou & Fennane (2009: 28); Gonçalves et al. (2014: 273). Calendula echinata subsp. murbeckii (Lanza ex Murbeck (1923: 59)) Maire in Jahandiez & Maire (1934: 788); Ohle (1975a: 13). Type:— MOROCCO. Environs de Marrakesh: Aviation, champs arides, 1921, Murbeck s.n. (holotype LD! [1217767]; isotype MPU! [00819]).

Description:––Annual to short-lived perennial herbs. Stems (6) 22–46 (89) cm long, ascending to diffuse, with glandular hairs. Basal leaves (2.5) 3.5–6.7 (9) × (0.2) 0.3–0.6 (1.1) cm, with (0.2) 0.3–0.4 (0.6) mm thick, linear to oblanceolate, apex acute to slightly acuminate, margins sinuate-dentate, with acute teeth, to ± irregularly pinnatifid, glandular pubescent. Capitula solitary, (2) 2.7–3.4 (4.7) cm diameter, concolorous, yellow to orange. Achenes heteromorphic: outer achenes rostrate (14) 16.3–23 (26) × (1.2) 1.5–1.8 (3.3) mm, ± straight or slightly curved, with dorsal spines or muricate; middle achenes trialate (8.3) 9–10.5 (11.3) × (5) 5.8–8.3 (10.8) mm, lateral wings deeply pinnately cut into segments with truncate apices; inner achenes vermiculate-alate (3.8) 4.3–5.6 (6) × (2.2) 3.1–5.6 mm, with basal and apical teeth; and vermiculate-exalate (3.3) 3.8–4.5 (4.7) × (1) 1.2–1.3 (1.7) mm, both circular to hemicyclic. Figure 16 .

Habitat and distribution:— Clay-limestone rocks,at elevations between 20–150 m. It is found in arid Mediterranean bio-climate. Endemic to Morocco with a distribution restricted to Marrakesh (Jbilet and Lalla Takerkoust). Figure 13 .

Conservation status:—Endangered (EN). This species is under numerous threats, especially due to climate change, drought, development (infrastructures, urbanisation), human interference and grazing. The species is rare and local with a small-restricted range; at present, we only know two populations, one in a reserve of gazelles and another near the Lalla Takerkoust barrage. The classic population disappeared due to the development of the airport. The number of mature individuals is estimated to be <250 based on field observations. The EOO is 124.946 km 2 and the AOO is 12 km 2, both qualifying the species for EN. There was an observed decline, and it is projected to occur a future continuing decline in the EOO and AOO, extent and quality of the habitat, number of locations/subpopulations and number of mature individuals. Therefore, we propose the species conservation status as EN B1ab (i, ii, iii, iv, v) + 2ab (i, ii, iii, iv, v), C2a (i), D.

Chromosome number:— 2n = 18.

Genome size:—2.07 ± 0.14 pg.

Notes:— Murbeck (1923: 59) described this species as displaying only trialate and vermiculate achenes, without specifying which was the type of vermiculate achenes (i.e. alate or exalate). Later Maire (1928b: 56) confirmed the existence of rostrate, trialate, cymbiform and vermiculate-exalate achenes in this species. We have not seen any specimen (in field or herbarium) with cymbiform achenes. Therefore, either Maire (1928b: 56) considered as cymbiform the vermicular-alate achenes, or the specimen he observed was a hybrid. We observed in the field that two, or more, different combinations of achenes may appear in the fruiting capitula. For example, we observed plants with rostrate, trialate, vermiculate-alate and vermiculate-exalate achenes and others lacking the trialate achenes. Nègre (1958: 5) made some observations on C. murbeckii under cultivation: the first generation came out with the same characteristics as the parents, but the second generation displayed intermediate characteristics between C. stellata and C. murbeckii . However, we cannot exclude that this variability result from cross-pollination with some C. stellata that Nègre had growing in the garden at the same time. Maire in Jahandiez & Maire (1934: 788) determined all C. murbeckii specimens collected in the Anti-Atlas coastal region (environs of Mogador, collines des Haha, Agadir, Sous) as C. echinata . Later, Maire (1938: 424) revised his assesssment of C. echinata subsp. murbeckii and recognised this taxon at species level. Maire (1938) considered that the type of C. echinata , also from Mogador (Broussonnet s.n. G00457529) was merely a form of C. arvensis , as he also indicated in the label he added to the specimen in 1938. C. murbeckii has been included by recent authors (e.g. Ohle 1975a: 13) in C. maroccana ; however, we agree with Maire (1938: 424) that C. murbeckii is a distinct species, particularly in view of the different life form, achene morphology and 2C values.

Additional collections:— MOROCCO. Marrakech-Safi: Jbilet, near to the house of the gazele reserve, 624 m [31°52’09” N, 7°57’08” W], 25 March 2013, P . Silveira, A. C. R. S . Gonçalves & A . Ouhammou 3280 ( AVE!); S of Barrage Lalla Takerhust , 729m [31°21’36” N, 8°09’46” W], 25 March 2013, P . Silveira, A. C. R. S . Gonçalves & A . Ouhammou 3287 ( AVE!) .

Figures

FIGURE 13. Geographic distribution of the species included in the Calendula maroccana group.

FIGURE 16. Variability of achene morphology of Calendula. A. C. meuselii (Silveira 3063, AVE); B. C. eckerleinii (Silveira 3064,AVE); C. C. oualidii (Silveira & Gonçalves 3339,AVE); D. C. davisii (Silveira & Gonçalves 3263,AVE); E. C. maroccana (Silveira 3144,AVE); F. C. maroccana (Silveira, Gonçalves, & Ouhammou 3295, AVE); G. C. murbeckii (Silveira, Gonçalves, & Ouhammou 3280, AVE); H. C. lanzae (Silveira, Gonçalves, & Ouhammou 3293, AVE); I. C. pinnatiloba (Silveira 3137, AVE); J. C. stellata (Silveira 3137, AVE); K. C. stellata (Silveira 3062, AVE); L. C. tripterocarpa (Silveira 3068, AVE). Rostrate achenes: A1, 2; B1, 2; C1, 2; D1, 2; E1-3; F1, 2; G1-4; H1-2; I1, 2; J1, 2; K1. Bialate achenes:A3, 4; B3, 4; E4, H4-6; K2. Cymbiform achenes: E7, 8; G7; H7, 8; I6; J3, 4; K4, 5; L2, 3. Trialate achenes: B5, 6; C3, 4; D4, 5; E5, 6; F3, 4; G5, 6; I3, 4; L1. Vermiculate-alate achenes: H9; J5; K6; L4. Vermiculate-exalate achenes:A5; B7; B8; C5, 6; D6, 7; E9, 10; F5, 6; G8; H10, I7, J6, K7; L5. All achenes in side view, except:A3, B4, B5, C3, D3, D5, E4, E5, F3, G5, H4, H5, H7, I3, I5, I6, J3, K2, K4, L1 and L2 in ventral face view, and A4, B3, B6, C4, D4, E6, F4, G6, H6, H8, I4, J4, K3, K5 and L3 in ± dorsal face view. Scale bars = 1 cm.