Sonchus boulosii

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Sonchus boulosii

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Etymology

The epithet honours the Egyptian botanist and monographer of Sonchus in the 1970s Loutfy Boulos (1932–2015).A

Description

"Perennial herbs, 3–17 cm high, with a woody rootstock, stemless, cushion-shaped, unarmed, with long, pluricellular, uniseriate, woolly hairs and other unicellular glandular hairs. Rootstock densely branched, covered with leaf remains, with numerous erect or ascending branches of 4–30 mm in diameter. Leaves 0.6–5.2(–17) × 0.4–2.6 cm, arranged in basal rosettes, spiral alternate, simple, pinnatifid to pinnatisect, ± lyrate, narrowly obovate in shape, attenuate to the base with poorly defined petiole, with pinnate-reticulate venation, margin entire with some small, cartilaginous teeth sparsely distributed, with white, woolly hairs in the axil, green colored, sometimes purple-stained; (2–)4–7 lateral lobes 0.2–0.9 × 0.3–0.8 cm, ovate to rhomboidal, often rounded at the apex, sometimes acute and mucronulate; terminal lobe 0.6–2.6 × 0.4–2.6 cm, ovate to deltoid or, more rarely, reniform. Capitula terminal, often solitary with scapiform peduncles, sometimes in loose panicles up to 3 flower heads, including (41-)60-138(–160) florets; peduncles up to 14 cm in length and 0.2–0.4 mm in diameter, erect, cylindrical, angled, covered by simple glandular hairs 0.2–0.7 mm, more abundant in the upper third, sometimes glabrous, commonly with 1 or 2 bracteoles of 1.3–4.2 mm, woolly in the axil. Involucre 7.0–11.0 × 3.8–8.3 mm, nonaccrescent, cylindrical during anthesis and conical-campanulate during the maturation of fruits, with 16–26 involucral bracts per capitulum, arranged in three roughly-defined series. Involucral bracts adpressed, plane, acute to erose at the apex, green colored; outer and middle ones 5–9, 1.4–7.4 × 0.5–1.7 mm, lanceolate, often with glandular hairs mainly in the median axis (sometimes glabrous), with narrowly membranous margin; inner ones 8–18, 7–11 × 1–2.6 mm, lanceolate to linear, glabrous, with a well-developed membranous margin. Receptacle ± alveolate, with few small scales sparsely distributed. Florets ligulate, hermaphrodite. Corolla 6.1–11.9 mm; tube 2.1–5.3 mm, hairy in the upper part; ligule of the outer florets 4.2–8.1 × 1.5–3.2 mm, shorter inwards the flower head, oblanceolate to ± linear, with 5 teeth at the apex, commonly bright yellow in color but the external ones with a purple band on the back. Anthers 2–3.6 mm, sagittate at the base and rounded at apex, commonly longer inwards the flower head, yellow. Style branches 0.7–1.9 mm, linear, yellow. Achenes 2.2–3.4 × 0.4–0.7 mm, fusiform, linear or narrowly oblanceolate, not beaked, somewhat laterally compressed, with clearly defined outline by two thick marginal ribs, and a thick central main rib plus up to 4 secondary ribs on each side, in general transversally tuberculate-spinulose. Pappus 3.2–4.9 mm, of scabrid-scabridulous bristles, dimorphic, early deciduous, white; outer bristles 1.8–3.1 mm, fine and flexuose, connate at the base; the inner ones thicker, straight, not connate."A

Systematics

Sonchus boulosii shares its habit of a pulvinate rosette shrub with branched woody caudex and its habitat of crevices in subvertical cliffs with several other species of the genus. Phylogenetic reconstruction based on nrITS and matK plastid DNA shows that cliff-dwelling occurs in several clades and that this species is also not closely related the other Moroccan species with similar habit and ecology, but forms a clade of its own. Mejías & al (2018) therefore establish the new section Pulvinati in S. subg. Sonchus to accommodate this species. A

Chromosome numbers

The species is diploid with a basic number of x = 9.A

Distribution

Africa: Morocco (MorocconativeA)

Habitat and ecology

Sonchus boulosii grows in crevices of sub-vertical, mainly NNW–NNE-facing limestone cliffs at elevations of 1400–2400 m. The known populations are spread across an area of c. 15 000 km² in E Morocco including meso-Mediterranean to montane-Mediterranean vegetation belts and a mean annual precipitation of c. 400–700 mm. The idividual populations occupy only areas of 0.1–0.5 km² with a few hundred to up to 1000 individuals.A

Bibliography

A. Mejías J. A., Chambouleyron M., Kim S.-H. & al., Phylogenetic and morphological analysis of a new cliff-dwelling species reveals a remnant ancestral diversity and evolutionary parallelism in Sonchus (Asteraceae) in Pl. Syst. Evol. 304: 1023-1040. 2018