Heuchera lakelae Folk, 2013

Folk, Ryan, 2013, Heuchera lakelae (Saxifragaceae), a new species from the Sierra La Marta and Sierra Coahuilón, Coahuila and Nuevo León, Mexico, Phytotaxa 124 (1), pp. 37-42 : 38-39

Heuchera lakelae Folk , sp. nov. ( Fig. 1 )

A Heuchera sanguinea Engelm. flore albo-rubescenti cylindracei vel leviter bucciniformi, hypanthio et sepalo dense glanduloso-hirsuto, petalis albis valde exsertis rhomboideo-spatulatis vel ovato-spatulatis, staminibus leviter inclusis, crescenti supra 3200 m altitudinis differt.

Type:— MEXICO. Coahuila: Sierra La Marta E of Cerro Moro [Cerro el Morro], ca. 3400 m alt., 22 July, 1985. S . Ginzbarg 134. (Holotype NY!, isotypes MO!, TEX!, MEXU!)

Description:— Perennial herb, subcaulescent from a multicipital thick caudex. Petioles glandular-villous and glandular-pulverulent, (1.5–) 3–10 cm long. Leaf blades (1–) 2–5 cm wide and (1.25–) 1.5–4 cm long, orbicular to ovate, deeply cordate with a narrow or wide sinus, shallowly divided into 5–7 lobes with narrow sinuses; teeth large and coarse, triangular to crenate and mucronate; adaxial surface sparsely to densely glandular-villous as well as glandular-puberulent, abaxial surface similarly vestitured but the longer hairs restricted mainly to the veins. Margin moderately ciliate. Inflorescences indeterminate scapiform thyrses (11.5–) 18.5–45 cm long, the flowers rather crowded and becoming interrupted proximally, the bracts highly reduced, rarely having a large leaf-like bract, the lowest pair of bracts subopposite, primary axis glandularhirsute proximally to glandular-puberulent distally; cymules 2–7 flowered, 1.5–5.5 cm long, monochasial or often dichasial at the first branching. Flowers 5–7 mm long, external surface white aging to pale pink, puberulent proximally and becoming strongly hirsute-glandular distally; hypanthia campanulate, moderately zygomorphic, 2.5–3.5 mm long on the adaxial side, (2.5–) 3–6 mm wide; sepals rounded, (1–) 1.5–3 mm long; petals 2–3 mm long, white, ovate-spatulate to rhombic-spatulate with a prominent claw, exceeding the sepal tips, adnate to free hypanthium just below the sepal sinuses; stamens 1.5–2 mm, slightly or strongly included, filaments adnate to free hypanthium about halfway between the base and the level of the sepal sinuses, anthers ovate; closed true styles about 1 mm, stigmas capitate. Capsule 8–10 mm long, 4–5 mm wide, ovoid, exceeding slightly the accrescent calyx. Seeds about 0.7–0.8 mm long, fusiform but somewhat lunular, beset with short spines.

Phenology:— Flowering June–September (–October), fruiting August–October.

Distribution:— The rocky slopes of El Coahuilón and Cerro El Morro in the Sierra Coahuilón and Sierra la Marta, along the border between Coahuila and Nuevo León just south of Monterrey, northern Sierra Madre Oriental, Mexico.

Habitat:— Moist north-facing rock outcrops or talus slopes, mostly on limestone, 3250–3700 m, subalpine or alpine zone. Alpine specimens much dwarfed. Some plants, including the type collection, are reported from the pioneer vegetation of recently burned pine forests.

Associates:— Pseudotsuga menziesii, Pinus rudis, P. culminicola , P. hartwegii, Abies vejari, Holodiscus sp., Salix sp. , Quercus sp. , Garrya sp. , and Symphoricarpos sp.

Conservation:— Known from only an extremely narrow range of about 6 km in width; a possible candidate for conservation listing, but field work is needed to establish the size and stability of these populations.

Etymology:— For Olga Lakela, whose dissertation work led to an exemplary and well-regarded 1936 monograph on Heuchera , the most recent such work to include Mexican species.

Other specimens examined:— MEXICO: Coahuila: El Coahuilón, Sierra de la Marta, mpio. Arteaga , 25°14'12 N, 100°18'40” W, 3600 m, 9 October 1986, J. A . Villareal 3467 ( MEXU, BRIT); El Coahuilón, Sierra de la Marta, mpio. Arteaga, 25°14'12 N, 100°18'40” W, 3600 m, 6 August 1987, J. A . Villareal 3818 ( TEX); El Coahuilón, Sierra de la Marta, mpio. Arteaga , 25°14'12 N, 100°18'40” W, 3600 m, 17 October 1989, J. A . Villareal 5471 ( TEX); El Coahuilón, Sierra de la Marta, 25°14'12 N, 100°18'40” W, 3600 m, 17 October 1989, J. A . Villareal 5473 ( XAL); Rocky knoll, Sierra la Marta , 3450 m, 6 September 1981, G. B . Hinton 18331 ( TEX); Cliff in pine forest, S . del Coahuilón, mpio. Arteaga , 3250 m, June 2, 1985, G. B . Hinton 18855 ( TEX); Estepa alpina, Cerro del Morro en ladera sur, Sierra la Marta , ca. 3700 m, 17 June, 1985, McDonald 1470 ( TEX); Ladera sur, zona subalpina, Sierra Coahuilón, ca. 3400–3500 m, 18 June 1985, McDonald 1521 ( TEX) . Nuevo Leon: Sierra la Marta, mpio. Galeana ?, 3400 m, 4 August 1980, G. B . Hinton 17912 ( TEX, MEXU) ;

Figures

FIGURE 1. Drawing of H. lakelae, prepared from the type material at NY and TEX by the author. A. Habit and inflorescence; scale represents 4.5 cm. B. Dissected flower; scale represents 6 mm. C. Side view of flower; scale represents 6 mm.