Xenophyllum marcidum (S.F.Blake) V.A.Funk, Novon 7(3): 240. 1997.

Calvo, Joel & Moreira-Munoz, Andres, 2020, Taxonomic revision of the Andean genus Xenophyllum (Compositae, Senecioneae), PhytoKeys 158, pp. 1-106 : 1

8. Xenophyllum marcidum (S.F.Blake) V.A.Funk, Novon 7(3): 240. 1997.

Werneria marcida S.F.Blake, J. Washington Acad. Sci. 18: 492. 1928. Type. Peru. Lima: Río Blanco, 4570 m, 20/25 Mar 1923, J.F. Macbride 3032 (holotype: F-534102!; isotypes: BM s.n.!, G-00305676 (fragment, digital image!), G-00305677 (digital image!), GH s.n.!, MA-246360!, S-R-6525 (digital image!), US-00037326!, W-3718!).

Werneria sedoides S.F.Blake, J. Washington Acad. Sci. 18: 493. 1928. Type. Peru. Ancash: Punco, Estación 21 miles West of Huallanca, 4115 m, 1 Oct 1922, J.F. Macbride & W. Featherstone 2475 (holotype: F-518901!; isotypes: US-00037308!, G-00305678 (fragment, digital image!), G-00305679 (digital image!)).

Description.

Suffruticose plant, forming dense mats or hummocks, with rhizome-like stems up to 8 cm long covered with old leaves, rather erect, simple or branched from the base. Stems 1-2 cm tall (aerial part), glabrous. Leaves densely imbricate, extending into a glabrous sheath-like base; leaf laminas 3.3-7.6 × 1.7-2.6 mm, triangular, acute at the apex, denticulate in the upper half, rather flat in cross section, glabrous, 1-nerved above (barely visible), 1-nerved beneath, rather fleshy, matte. Capitula radiate, erect, sessile to subsessile. Involucres 8.8-10.8 × 5.7-10 mm, cupuliform; involucral bracts 13 to 15, 4.8-6.7 × 1.8-2.2 mm, acute at the apex, greenish to dark-purplish. Ray florets 14 to 21; corollas 7.4-12.9 × 1.6-2.3 mm, 3 to 4-veined, subentire to 2-toothed at the apex, conspicuously surpassing the involucre, white. Disc florets 35 to 48; corollas 5-6.2 mm long, yellowish; style branches truncate with a crown of sweeping trichomes, purplish. Achenes 2.8-3 × ca. 1 mm, cylindrical, ca. 7-ribbed, glabrous; pappus 5-8.8 mm long, barbellate, whitish to partially purple-colored. Chromosome number unknown. Fig. 14 .

Additional iconography.

Blake (1928: 496, fig. 1H-J sub Werneria marcida , fig. 1N-P sub W. sedoides ); Funk (1997a: 237, fig. 1B); Beltrán (2016: 358, fig. 2B, as photo).

Distribution and habitat.

Central Peru to northern Bolivia. Bolivia (La Paz), Peru (Ancash, Arequipa, Ayacucho, Huancavelica, Huánuco, Junín [expected], Lima, Moquegua [expected], Pasco [expected], Puno). It grows on exposed rocky slopes and cryoturbated soils of the subhumid and humid puna ecoregions, between elevations of 4550-5350 m (Fig. 15 ).

Phenology.

Flowering from February to September.

Etymology.

The adjective marcidus -a -um means withered. It probably refers to the fact that a large proportion of the stem bears marcescent leaves and the green ones are restricted to the distal part.

Notes.

Xenophyllum marcidum is characterized by its triangular, densely imbricate leaves. Among the Xenophyllum members forming dense mats or hummocks, this species is readily distinguishable due to the leaves are denticulate in the upper half, acute at the apex, and rather flat in cross section. The capitula are radiate and have 14 to 21 ray florets with white, considerably long corollas.

Because of the marginally denticulate leaves, on dried specimens X. marcidum might be confused with X. ciliolatum , a species that has a partially overlapping distribution area. They can be easily differentiated by the habit (forming dense mats or hummocks in X. marcidum vs. forming clumps of erect or decumbent stems in X. ciliolatum ), leaf lamina shape (triangular in X. marcidum vs. linear in X. ciliolatum ), number of involucral bracts (13 to 15 in X. marcidum vs. ca. 8 in X. ciliolatum ), number of ray florets (14 to 21 in X. marcidum vs. 8 to 11 in X. ciliolatum ), and by the ray corolla length and color (7.4-12.9 mm, white in X. marcidum vs. 6.2-7.3 mm, yellow in X. ciliolatum ).

Additional specimens examined.

Bolivia. La Paz: Murillo, nev. Charquini, above aqueduct on N facing slope, 16°17'S, 68°6'W, 12 Apr 1995, V.A. Funk & N. Bernal 11285 (LPB, US); Bautista Saavedra, Charazani, miterhalb Medallani, 15°4'S, 69°6'W, 17 Feb 1994, B. Herzog 795 (LPB); Murillo, subida del paso de Zongo (acueducto), al nev. Charquini, 16°17'S, 68°6'W, 30 Jul 1982, X. Menhofer 1461 (LPB, US); Murillo, paso de Zongo, nev. Charquini, 16°17'S, 68°6'W, 1 Aug 1982, X. Menhofer 1461A (LPB); Franz Tamayo, Pelechuco, al N en línea recta a 0.58 km del campamento Chocollo, 14°43'S, 69°13'W, 25 Nov 2017, F. Zenteno, D. Villalba & L. Mamani 21274 (LPB). Peru. Ancash: Recuay, carretera a Pachacoto, abra de Yanashallash, 9°50'S, 77°8'W, 28 May 2001, A. Cano 11496 (USM); Carhuaz, Huascarán N.P., lateral valley of quebrada Ishinca, trail to lago Ishinca, 9°23'S, 77°25'W, 12 Feb 1985, D.N. Smith, R. Valencia & A. Gonzales 9469 (LPB, MO, QCA, USM); collado sobre el río Pumapampa, 18 Mar 1983, O. Tovar et al. 9627 (USM); collado encima río Pumapampa, 18 Mar 1983, O. Tovar et al. 9666 (USM); nevado de Cajat, entre Huaraz-La Unión, 22 Mar 1983, O. Tovar et al. 9842 (USM); Arequipa: Castilla, Orcopampa, minas de Poracota, quebrada Huamanihuayta, 15°13'S, 72°30'W, 20 Apr 2011, H. Beltrán 7101 (USM); Ayacucho: Ayacucho, abra Apacheta, camino a Pars, 13°25'S, 74°40'W, 4 Aug 2010, A. Cano, W. Mendoza & A. Delgado 19760 (USM [mixed with Werneria orbignyana Wedd.]); Huancavelica: Huachocolpa, alrededores de la unidad minera Caudalosa, 13°4'S, 75°0'W, 23 Mar 2015, P. Gonzáles 3544 (USM); San José de Acobambilla, top of quebrada Ocrococha, 12°40'S, 75°22'W, 12 Aug 1961, J.R. Lloyd & J.K. Marshall 309 (K); Huánuco: Dos de Mayo, Lauricocha, 10°18'S, 76°39'W, 1955, A. Cardich 208 (USM); Dos de Mayo, Gayco, 10°24'S, 76°46'W, Apr 1956, A. Cardich 217 (USM); Lima: Huarochirí, desvío de carretera central hacia Chinchan y Marcapomacocha, 11°34'S, 76°15'W, 23 Sep 2014, H. Beltrán & W. Aparco 7750 (USM); Oyón, encima de mina Uchuchacua, parte más alta por carretera, 10°36'S, 76°40'W, 5 Apr 2015, H. Beltrán & W. Aparco 7769 (USM); Huarochirí, Chicla, abra Anticona (Ticlio), 11°35'S, 76°11'W, 29 Apr 2017, H. Beltrán, S. Castillo & M. Arakaki 7986 (USM); Ticlio bajo, 11°35'S, 76°11'W, 16 May 1959, L. Diers 940 (USM); Huarochirí, San Damián, Chanape, 11°53'S, 76°15'W, 5 Jul 2013, P. Gonzáles & B. Brito 2632 (USM); Anticona, pequeño arroyo con orientación SW, 11°35'S, 76°11'W, 5 Aug 2012, E. Linares & A. Galán 3077 (USM); Puno: Carabaya, Corani, Minaspata, 14°1'S, 70°41'W, 15 Oct 2017, P. Gonzáles 3832 (USM); San Antonio de Esquilache, 16°6'S, 70°17'W, 18 May 1937, D. Stafford 749 (K).

Figures

Figure 14. Xenophyllum marcidum A habit B stem apical part and capitulum C capitulum D adaxial leaf surface E uppermost leaf F ray corolla and style G disc corolla and style branches H disc corolla and stamens (vertically sectioned, style removed) I style J achene with pappus. All details drawn from Funk & Bernal 11285 (US) except for A (drawn from Stafford 749, K) and C-E, H (drawn from Macbride & Featherstone 2475, US). Illustration by Alice Tangerini.

Figure 15. Distribution map of Xenophyllum marcidum (left hand) and X. ciliolatum (right hand).