Leontodon rigens

Moura, Mónica, Silva, Luís, Dias, Elisabete F., Schaefer, Hanno & Carine, Mark, 2015, A revision of the genus Leontodon (Asteraceae) in the Azores based on morphological and molecular evidence, Phytotaxa 210 (1), pp. 24-46 : 37-38

Leontodon rigens (Dryander in Aiton) Paiva & Ormonde (1973: 448)

≡ Crepis rig ens Dryander in Aiton (1789: 127) ≡ Microderis rigens (Dryander in Aiton) DC (1838: 128) ≡ Picris rigens (Dryander in Aiton) Benth & Hooker f. (1873: 512) ≡ Hieracioides rigens (Aiton) Kuntze (1891: 346) .

Holotype:— AZORES. “Nat. of the Azores, Mr. Francis Masson. Introd. 1778” ( BM!).

− Hypochaeris strigosa Solander ex Lowe (1868: 537) nom. non rite public.

Acaulous rosettiform rhizomatous perennial herb; white latex present. Rootstock usually stout, woody, sometimes a long napiform root. Leaves few to several (1–14), petiolate. Petiole (1-) 8 (-17) cm long × (0.2-) 1.2 (-3.5) cm wide, grooved, often narrowly winged; petiole trichomes often simple. Leaf (5-) 18 (50) cm long × (3-) 7 (-12) cm wide; elliptic to ovate, sometimes lanceolate or almost obovate, attenuate at base onto apex of petiole; usually sparsely to densely pubescent above and densely pubescent beneath, hairs about 1 mm long or longer and attenuate, apices simple and straight, curved or appearing almost uncinate or often bifid; venation pinnate, usually paler than lamina, midrib prominent beneath with many hairs, grooved above; margins flat to coarsely undulate, serrate, coarsely serrate, tooth acuminate, or sometimes deeply lobed at base, lobes simple or sometimes bifid; lamina apices acute, obtuse or rounded. One or two flowering stipes up to (32-) 45 (-69) cm tall, erect; ramification generally initially dichotomous at the base, with 2–7 proximal ramifications and with multiple distal ramifications; corymbose panicle, barely aphyllous, stipe striate, moderately hispid pubescent at the base but almost glabrous at peduncles and pedicels, usually with one leaf-like bract beneath each main branch and scale-like bracteoles beneath upper branches; stipe trichomes simple to bifid; pedicels (1.2-) 3.6 (-7.0) cm long, usually thickening below involucre, bracteolate, bracteoles scale like, (1.5-) 3 (-8.2) mm long, narrow triangular entire; the pedicel bracteoles sometimes also found at the base of the capitulum forming an incomplete, unequal calyculus around 2–3 mm long. Capitula ligulate, (0.6-) 1.4 (-2.4) cm in diameter, (14-) 59 (- 114) per synflorescence; involucre cylindrical in bud and scarcely widening in flower at apex, base becoming slightly inflated postanthesis and in fruit; phyllaries biseriate, external bracts (0.9-) 2.6 (-4.6) mm long, internal bracts (3.99-) 7.7 (-11.4) mm long × (0.3-) 0.9 (-1.9) mm wide, margins glabrous below and sparsely ciliate towards apex, tissue papillate and usually blackish; receptacle flat, paleaceous, paleae 4.4–14,0 mm long × 0.1–0.7 mm wide, linear, usually with dark margins, apices attenuate/long-acute, sparsely to moderately ciliate, cilia long uniseriate and eglandular. Florets (26-) 37 (-56) ligulate, hermaphrodite, fertile, corollas yellow to orange, but becoming pale brown postanthesis, eventually deciduous; corolla tube (1.2-) 3.0 (-5.8) mm long, glabrous, pale yellow, ligule (5.6-) 10.0 (-19.1) mm long × (0.3-) 0.8 (-1.6) mm wide, glabrous inside, sparsely pubescent outside just above sinus with eglandular hairs, ligule apex with five distinct teeth, teeth apices thickened, glabrous; anther cylinder yellow (1.4-) 3.8 (-9.0) mm long, apical anther appendages obtuse to broadly rounded, slightly longer than wide, basal anther appendages sagittate; styles (3.2-) 5.2 (-11.5) mm long, style arms (0.2-) 1.0 (-2.4) mm long, ascending or divergent, very short pubescent outside throughout. Achenes pale brown, (0.6-) 3.2 (-6.3) mm long × (0.1-) 0.4 (-1.1) mm wide, narrowly fusiform, narrowing slightly upwards to a distinct apical callus, body striate, lightly rugose across striae; pappus setae (3.6-) 5.9 (-8.0) mm long, setae at first coarsely scabrid, and about as long as corolla tube, maturing to plumose or subplumose, with setae rachis coarsely barbellate. Molecularly differs from all other Azorean Leontodon in 4 positions of the ITS region, in the motifs GATG T GGAG (G replaced by T), CCCT G CCGG (C replaced by G), TAGG A AAGC (G replaced by A) and GTTT C AGGA (T/G replaced by C); and in one position of the trnQ region, in the motif ACAA A AAAA (T replaced by A).

Distribution:— Leontodon rigens is an endemic of São Miguel Island.

Habitat:—Generally not below 300 m. In moist habitats on steep slopes, roadsides, in the margins or in the openings of the native scrubland ( Calluna vulgaris ) and of the native forest ( Laurus azorica , Ilex perado subsp. azorica , Juniperus brevifolia ). Also in open grassland, on cuttings through sandy deposits and on cliffs. In crevices on vertical cliffs and on dense humus layers or Sphagnum spp. carpet on slopes in ravines and craters, also associated with Festuca francoi or Deschampsia foliosa .

Phenology: —See L. hochstetteri .

Conservation Status:—Previous attempts to classify L. rigens according to IUCN criteria led Corvelo (2010) to list it as Endangered [B2ab (i, ii, iii)]. It was also considered a top priority species by Silva et al. (2009). However, these estimations also included the western Leontodon species. Population numbers were estimated by Schaefer (2005) (as “ Leontodon spec. nov. ined. ”) to be <1,000. During the extensive sampling conducted for this study and by Dias et al. (2014), 14 populations of L. rigens were identified in fragmented native vegetation patches in the central part and the eastern and western extremes of São Miguel , with an estimated total number of <4,000 individuals. In several of these locations (e.g. Lagoa do Fogo and Sete Cidades waterbasin locations), goats can be found grazing, although the areas are part of the São Miguel Natural Park. Furthermore, wild rabbits are also known to feed on the plants. Thus, according to the IUCN classification, and based on the estimated number of plants, L. rigens would be considered as Vulnerable (V) B1ab(i,ii,iii)+2ab(i,ii,iii); C2a(i).