Senecio scapiodes Aguilar-Cano & D.J.N.Hind

Aguilar-Cano, J., Hind, D.J.N. Senecio scapioides (Compositae: Senecioneae: Senecioniinae): a new species from the Departamento de Boyacá, in Andean Colombia. Kew Bull 75, 35 (2020). https://doi.org/10.1007/s12225-020-9884-4

Morphology General Habit

Rhizomatous, single-stemmed perennial herbs up 45 cm tall; basal stem creeping, decumbent, thin-woody, 1.5 – 3.5 mm diam., unbranched

Morphology Reproductive morphology Inflorescences

Inflorescence scapiform, erect, 15 – 37 cm tall, purple, indumentum densely arachnoid and sericeous, white, covering stems, abaxial leaf surface and involucre, together with glandular, simple multicellular-uniseriate, whitish hyaline trichomes 1.4 – 2.8 mm long, composed of 22 – 36 (– 42) short-oblong cells, these becoming gradually smaller towards apex, ending in a rounded cell

Morphology Leaves

Basal leaves 15 – 20 together in a loose rosette, these present at anthesis, leaf blade narrowly oblanceolate-oblong to oblanceolate-oblong, 22 – 45 (– 50) × 3 – 6 mm, sessile, lamina base abruptly attenuate and not dilated at node, herbaceous, pubescent especially along margins, on apex and veins, abaxially whitish green to purple, with an arachnoid and sericeous indumentum, adaxially green, midrib purple, margins entire to obscurely dentate and moderately revolute, apex acute-apiculate; cauline leaves 7 – 15, dissimilar to basal leaves, sparser and gradually smaller towards stem apex, sessile, base dilated but not auriculate, blade narrowly oblong-lanceolate or linear-lanceolate, 16 – 28 × 3 – 5 mm, herbaceous, adaxially green, densely sericeous-pubescent, abaxially completely purple and indumentum densely arachnoid and pubescent, midrib purple, margins dentate and strongly revolute, apex acute-apiculate

Morphology Reproductive morphology Inflorescences Capitulum

Capitula heterogamous and radiate, solitary and nodding; involucre campanulate, 10 – 33 × 16 – 43 mm, involucre closely subtended by a calyculus, calycular bracts 10 – 12, linear-lanceolate, 13 – 13 × 0.9 – 1.3 mm, herbaceous, green and apically purplish, densely arachnoid and sericeous, apex acuminate with a tuft of short glandular, unicellular trichomes; phyllaries 15, uniseriate, linear-lanceolate, 14 – 17 × 1.3 – 2.5 mm, herbaceous, green, apically purplish, indumentum arachnoid and sericeous, margins scarious, 0.4 – 0.8 mm wide, often fimbriate, apex acuminate with a tuft of short, glandular, unicellular trichomes; receptacle weakly convex, 5 – 6 × 9 – 10 mm, surface honeycombed

Morphology Reproductive morphology Flowers Florets

Ray florets 16 – 18, female and fertile, ray limb elliptic-oblong, 15.1 – 16.2 × 6.2 – 7.2 mm, yellow, glabrate, apex finely 3-dentate, 8-veined, corolla tube yellow, cylindrical, 5.9 – 6.4 mm long, densely pubescent towards apex with simple, glandular, multicellular uniseriate trichomes, 0.3 – 0.6 mm long; staminodes present; style yellow, 5.4 – 8.5 mm long, base dilated, style arms with marginal stigmatic lines, 1.3 – 2.1 mm long, apices truncate, covered by regularly distributed papillae

Morphology Reproductive morphology Fruits

Achenes ovate, 1.5 – 1.9 × 0.5 – 0.8 mm, covered with short, glandular, unicellular trichomes; carpopodium symmetrical in a broad ring, 0.2 mm diam.; pappus setae numerous, unequal, biseriate, 4.5 – 7.3 mm long, barbellate, deciduous, white Achenes cylindrical, 1.7 – 2.9 × 0.5 – 0.8 mm, covered with short, glandular, unicellular setulae; carpopodium a symmetrical broad ring, 0.2 – 0.3 mm in diam.; pappus setae numerous, biseriate, unequal, 6.2 – 9.5 mm long, barbellate, deciduous, white.

Disc

Disc florets numerous, 90 – 200, hermaphrodite, fertile; corollas bright yellow at anthesis (brownish post anthesis), 8.2 – 9.9 mm long, limb funnel-shaped, tube 3.0 – 3.6 mm long, glabrate, throat 4.4 – 5.4 × 1.1 – 1.5 mm, 5-lobed, triangular-ovate, 0.9 – 1.0 × 0.5 – 0.6 mm, abaxially thickened and adaxially with a tuft of papillae; anthers barely exserted, 2.8 – 3.0 × 0.2 – 0.4 mm, apical anther appendages lanceolate, anther bases calcarate, anther collars 0.8 – 1.0 mm long, in front view 0.2 – 0.3 mm and 0.1 – 0.2 mm wide (proximal and distal measurements respectively), in side view distally flattened and proximally elongate, balusterform, composed of 8 – 9 layers of rectangular cells; filaments flat, inserted below apex of corolla tube and adnate throughout; style yellow, 7.9 – 10.6 mm long, glabrous, style arms 1.7 – 2.2 mm long, with marginal stigmatic lines, apices sub-truncate to obtuse with a tuft of irregularly distributed papillae, longer papillae surrounding apex and shorter papillae covering whole surface of apex

Distribution

Senecio scapioides occurs in high grass páramos up to the lower limit of the superpáramo, at elevations of 3450 – 4053 m, throughout the north Cordillera Oriental of Colombia, including the páramo complexes of La Rusia, Iguaque-Merchan, Pisba and Tota-Bijagual-Mamapacha in the Department of Boyacá, and the complex of Chingaza in the Department of Cundinamarca, Colombia (Map 1). The species is a solitary terrestrial plant occurring as scattered individuals with low population density on the summits of mountains and on plateaus dominated by grass-stem rosette plant communities of Calamagrostis effusa (Kunth) Steud., Chusqueatessellata Munro (Poaceae) and EspeletiabarclayanaCuatrec. (Compositae)

Conservation

Senecio scapioides is endemic to Colombia, occurring in the Andean páramo, throughout the northern Cordillera Oriental in the Departments of Boyacá and Cundinamarca. The estimated extent of occurrence (5989 km2) is almost within the threshold for Endangered in criterion B1 and its area of occupancy is (348 km2) within the threshold for Endangered in criterion B2. The number and size of the populations is not well-known, and the species could not be accurately assessed based on its population size and decline. Nevertheless, the modern threats to habitat of livestock grazing and frequent fires, as well as climate warming and drying in the northern Andes (Vásquez et al. 2015; IPCC 2014), and more than a third of the Páramos de Boyacá now destroyed, mainly due to the introduction of grasslands and crops (Moreno et al. 2016), mean that the species habitat is in continuous decline. Therefore, following the criteria established by the IUCN (2013), Senecio scapioides is at present assessed as Endangered [EN B2 ab (iii)] mainly based on its distribution range. Research is urgently needed to establish the current population size of this new species, as well as to improve the understanding of plant diversity of Compositae in the Andean páramo.

Phenology

Flowering and fruiting simultaneously between November and January.

Note

The specific epithet derives from the Latin scapus (scape) and -oides (like) and alludes to the scapiform inflorescence of the species.