Sonchus subg. Palustres (Schchian ex Kirp.) M. Güzel 2022

Güzel, Murat Erdem, 2022, A new subgenus of Sonchus (Asteraceae: Cichorieae) inferred from molecular data, Phytotaxa 531 (3), pp. 211-229 : 223-224

Sonchus subg. Palustres (Schchian ex Kirp.) M. Güzel , stat. nov.

≡ Sonchus ser. Palustres Schchian ex Kirpicznikov (1964b: 341) .

— Type: Sonchus palustris L.

Description: Perennial herbs, with short-thick woody rhizome or tuberous root; stem erect, unbranched, hollow, lower part glabrous, upper part glandular-eglandular hairy or glabrous, striate. Leaves glabrous, margin denticulate, apex acuminate; cauline leaves decrease to synflorescence or basal leaves in a rosette, pinnatipartite to runcinate or linear-lanceolate, base sagittately clasping, sessile. Synflorescence corymbiform or paniculiform. Capitula including 40–90 flowers, narrowly to broadly campanulate, with long peduncles up to 3.5 cm or rarely subsessile. Phyllaries, in 2–3 series, dorsal face glandular-eglandular hairy, linear-lanceolate, apex acute. Flowers yellow, in 2–3 series, corolla 8.9–11.8 mm long, tube 2.8–3.9 mm, hairy in the upper part; ligule 5.9–7.5 mm style branches yellow. Achene slightly heteromorphic, not beaked, outermost slightly falcate, 5 main ribbed, weakly compressed in cross section; inner straight, 4 main ribbed, ± quadrangular in cross section; apex attenuate. Pappus heteromorphic, setaceous inner rays, thinner downy rays, scabrid, white, caducous as a unit.

Diagnosis: Morphological identification of Sonchus subg. Palustres is difficult because of the high similarity of their representatives with several members of S. subg. Sonchus and the paucity of morphological characters for the delimitation of sections and subgenus within Sonchus . In particular, the common aquatic habitat of S. subg. Palustres and S. sect. Maritimi makes the identification harder. However, S. subg. Palustres is distinct from rest of the genus by the following combination of morphological characters: slightly heteromorphic achenes, short-thick (up to 4–5 cm) woody rhizome (not creeping rhizome) or tuber and yellow stylus branches. The most similar species to S. subg. Palustres ( S. sosnowskyi was not examined except from digital specimens) is S. aquatilis which has also heteromorphic achenes. However, its root system (creeping rhizome) and grey stylus branches keep it separate from S. subg. Palustres.