Evergreen shrub to moderate-sized tree to 6(-10) m tall, with brownish to gray, longitudinally furrowed bark; twigs slightly to moderately angled, slender, sparsely to moderately lepidote, otherwise subglabrous to slightly (moderately) pubescent; buds ovoid, 0.8-2.5 x 0.8-2 mm.  Leaf blades elliptic to ovate, obovate, or nearly orbicular, 1.7-6.5(-9) x 0.7-4(-5.2) cm, ± flat to slightly abaxially curved, coriaceous, ca. 0.2-0.36 mm thick; base narrowly cuneate to rounded (very slightly cordate); apex acuminate, to acute, rounded, or truncate; margin plane to slightly revolute, the apical portion strongly to obscurely and irregularly toothed to entire, the basal portion entire to irregularly and obscurely toothed; venation brochidodromous, 3° veins ± reticulate; adaxial surface lepidote but scales usually quickly deciduous, sparsely to moderately pubescent on midvein, especially basal portion, the 3° and higher order veins visible to obscure, the 2° veins prominent to obscure, sometimes depressed; abaxial surface moderately lepidote, otherwise glabrous (sparsely pubescent on midvein only, near petiole), the 3° and higher order veins obscure to very slightly raised, not forming dense, fine, raised network, the 2° obscure to slightly raised and visible; scales rust colored, persistent to deciduous, ca. 0.1-0.34 mm in diameter, erose to entire; petiole 2-10 mm long, lepidote, otherwise pubescent adaxially or all around; flower buds ± intermixed with vegetative buds.  Inflorescences fasciculate, 4- to 16-flowered; pedicels clearly articulated with calyx, slender, 4-11 mm long, lepidote, otherwise glabrous to densely pubescent; bracts ± opposite, basal or nearly so, narrowly triangular, 0.9-2 mm long; floral bracts to ca. 2 mm long.  Flowers 4- or 5-merous; calyx lobes triangular, with acuminate apices, 0.7-1.5(-2) x 0.6-1.3 mm, adaxial side glabrous or sparsely pubescent, especially near apex, abaxial side lepidote, otherwise glabrous to sparsely pubescent; corolla cylindrical, white (pink tinged toward mouth), 4-8.5 x (2-)2.5-4 mm, abaxially sparsely lepidote; filaments roughened, 3-5 mm long, unappendaged; anthers 0.7-1.5 mm long; ovary lepidote, otherwise pubescent, placentae ± subapical.  Capsules ellipsoid to ovoid, (3-)3.5-6 x 1.7-3.5(-4) mm, slightly lepidote, otherwise sparsely pubescent, especially near base, the pale, very thick sutures separating as unit from adjacent valves; seeds 1.5-3 mm long.

    Distribution.  Hispaniola and Puerto Rico, in open forests of Pinus occidentalis, thickets, and cloud forests of various mountain ranges, at ca. (500-)1100-2100(-2300) m elev.
 

 Key to the Varieties of Lyonia stahlii

1.  Leaves entire to obscurely (occasionally clearly) toothed, secondary
     veins obscure to slightly depressed; flowers mainly 5-merous,
     corolla  4-6 mm long; Puerto Rico .............................. var. stahlii.
1.  Leaves irregularly toothed or notched, secondary veins often
     depressed;  flowers 5- and/or 4-merous, corolla (5.5-)6-8.5 mm
     long; Hispaniola ........................................................ var. costata.
 

Lyonia stahlii Urban var. stahlii, Symb. antill. 5: 453. 1908.  Xolisma stahlii (Urban) Small, N. Amer. Fl. 29(1): 71. 1914.  Lyonia rubiginosa (Persoon) G. Don var. stahlii (Urban) Judd, J. Arnold Arbor. 62: 355. 1981.  Lyonia rubiginosa (Persoon) G. Don subsp. stahlii (Urban) Borhidi, Acta Bot. Hung. 29: 188. 1983.  Illustrtion:  Judd (1995), fig. 14.  Type.  Puerto Rico, nr. Bayamón, in Monte Helechol, 500 m, 1885, A. Ståhl 468 (holotype, B, n.v., destroyed; frag. of holotype, NY).  Image:  Habit.

    Shrub to moderate-sized and often densely branched tree to 6(-10) m tall; twigs subglabrous to slightly (moderately) pubescent.  Leaf blades 1.7-6.5(-9) x 0.8-4(-5.2) cm, margin apically obscurely and irregularly toothed to entire (strongly toothed), basally entire to obscurely toothed; adaxial surface with the 3° and higher order veins faintly visible to obscure, the 2° veins obscure to visible, usually not depressed or only slightly so.  Pedicels slender, 4-11 mm long.  Flowers (4- or)5-merous; corolla 4-6 x (2-)2.5-4 mm.  Capsules 3.5-5.5 x 2-3.5(-4) mm.

    Distribution.  Endemic to Puerto Rico (Cordillera Central), in moist cloud forests, at ca. (500-)1100-1338 m elev.  Locally common on highest peaks of range (Cerro de Punta, Monte Jayuya, Cerro Maravillas, Pico Guilarte) in dense thickets or cloud forests.  Also in disturbed roadside vegetation; seedlings common on road-cuts or landslides (if near seed-source).  Flowering January through August.
 

Lyonia stahlii Urban var. costata (Urban) Judd, Fl. Neotrop. Monogr. 66: 263.  1995.  Lyonia costata Urban, Symb. antill. 7: 316. 1912.  Xolisma costata (Urban) Small, N. Amer. Fl. 29(1): 71. 1914.  Lyonia rubiginosa (Persoon) G. Don var. costata (Urban) Judd, J. Arnold Arbor. 62: 354. 1981.  Lyonia rubiginosa (Persoon) G. Don subsp. costata (Urban) Borhidi, Acta Bot. Hung. 29: 188. 1983.  Illustration:  Judd (1995), fig. 13.  Type.  Dominican Republic.  Between Constanza and Valle Nuevo, 1700 m, Apr 1910, von Tuerckheim 3119 (holotype, B, n.v., destroyed;  isotypes, F, GH, M, MO, NY, L, P, S, US).  Image:  Habit.

Lyonia acutifolia Urban & Ekman in Urban, Ark. Bot. 20A: 35. 1926.  Type.  Haiti.  Massif de la Selle, Morne Tranchant, Pétionville, on the ridge toward Godet, ca. 1850 m, 19 Sep 1924, Ekman H1949 (holotype, S;  isotypes, GH, IJ, K, NY, S, US).

Lyonia angulata Urban & Ekman in Urban, Ark. Bot. 20A: 35. 1926.  Type.  Haiti.  Massif de la Selle, Morne Cabaio, Jardin Bois Pin, ca. 1900 m, 25 Aug 1924, Ekman H1632 (holotype, S;  isotypes, IJ, S, US).

Lyonia darrasiana Urban & Ekman in Urban, Ark. Bot. 21A: 52. 1927.  Type.  Haiti.  Massif du Nord, nr. La Borgne, top of Morne Darras, ca. 1175 m, 3 Sep 1925, Ekman H4771 (holotype, S;  isotypes, IJ, S).

Xolisma longelaminata Sleumer, Repert. Sp. Nov. 36: 271. 1934. Lyonia longelaminata (Sleumer) Jiménez, Rhodora 62: 237. 1960.  Type.  Dominican Republic.  Santiago: Cordillera Central, Monción, Monte Gallo, ca. 1775 m, 10 Jun 1929, Ekman H12917 (holotype, S;  isotypes, A, GH, NY).

    Distribution.  Endemic to Hispaniola (Cordillera Central, Massif du Nord, Sierra de Neiba, Massif de la Selle, and Sierra de Baoruco, including Monteada Nuevo), in low-elevation Pinus occidentalis forests, thickets, and cloud forests, at (900-)1100-2100(-2300) m elev.  Flowering probably late March through early May.