Authority:

Luteyn, James L., et al. 1995. Ericaceae, Part II. The Superior-Ovaried Genera (Monotropoideae, Pyroloideae, Rhododendroideae, and Vaccinioideae P.P.). Fl. Neotrop. Monogr. 66: 560. (Published by NYBG Press)

Family:

Ericaceae

Synonyms:

Lyonia eggersii Urb., Xolisma tuerckheimii (Urb.) Small, Xolisma eggersii (Urb.) Small

Description:

Species Description - Evergreen, usually compact shrub to 2(-2.5) m tall, often from an underground woody burl, with gray, longitudinally furrowed bark; twigs slightly to moderately angled, stout, sparsely to moderately lepidote, otherwise usually densely pubescent; buds ovoid, 0.7-2 × 0.9-2 mm, lepidote. Leaf blades elliptic to ovate (obovate), 1.8-5(-6.5) × 0.8-2.5(-3.6) cm, ± flat, strongly coriaceous, ca. 0.35-0.47 mm thick; base narrowly cuneate to rounded; apex acute, rounded, or truncate; margin plane (very slightly revolute), apical portion strongly to obscurely and irregularly toothed, basal portion entire to obscurely toothed; venation brochidodromous, 3° veins ± reticulate; adaxial surface lepidote but scales usually quickly deciduous, densely pubescent on mid vein, sometimes sparsely pubescent on major 2° veins, the veins faintly visible to obscure, occasionally some 2° veins very slightly depressed; abaxial surface moderately lepidote, otherwise glabrous, but often sparsely to moderately pubescent on midvein, especially basal portion, the 3° and higher-order veins obscure to very slightly raised, not forming dense, fine, raised network, the 2° veins obscure to slightly raised and visible; scales rust colored, persistent to deciduous, ca. 0.08-0.25 mm in diam., erose to nearly entire; petiole 2.6-6(-8) mm long, lepidote, otherwise pubescent adaxially or all around; flower buds ± intermixed with vegetative buds. Inflorescences fasciculate (shortly racemose), 5-18-flowered; pedicels clearly articulated with calyx, slender, 4-13(-17) mm long, lepidote, otherwise usually densely pubescent; bracteoles opposite to subopposite, basal or nearly so, narrowly triangular, 1.3-2 mm long; floral bracts to ca. 3 mm long. Flowers 5(-6)-merous; calyx lobes triangular, with acuminate apices, 1.2-2 × 0.8-1.4 mm, adaxial side sparsely pubescent, especially near apex, abaxial side lepidote, otherwise glabrous to sparsely pubescent (near base); corolla cylindrical, white, usually slightly pink tinged, especially near mouth, (5.5-)6.5-10 × (2.4-)3-4.5 mm, abaxially sparsely lepidote; filaments roughened, 3-5.5 mm long, unappendaged (with very minute spurs near junction with anthers); anthers 1-1.5 mm long; ovary lepidote, otherwise pubescent, placentae ± subapical. Capsule ellipsoid to ovoid, 4-7 × 3-5 mm, slightly lepidote, otherwise sparsely to densely pubescent, especially near base, the pale, very thick sutures separating as unit from adjacent valves; seeds 1.2-2.5 mm long.

Discussion:

Lyonia tuerckheimii can be easily differentiated from the phenetically similar L. alainii and L. stahlii var. costata (members of a paraphyletic complex of Hispaniolan taxa, see "Infrageneric Relationships") by its much thicker and more robust branches that are densely covered with unicellular hairs and by the adaxial hypodermis of its leaves, which is two cells thick. Additional differentiating features are listed under L. alainii and L. stahlii. Lyonia tuerckheimii is isolated from both of the above taxa by habitat (and thus elevational) differences; it occurs chiefly in the high-elevation Pinus occidentalis forests above ca. 2000 m. It is easily distinguished from the possibly related species L. rubiginosa by its lack of unicellular hairs on the abaxial surface of its leaves and by its thinner, nearly glabrous stems. Young plants often have quite slender twigs and small, narrowly acute leaves that are more strongly toothed than those of mature plants.

Rare hybrids between Lyonia tuerckheimii and L. heptamera or L. urbaniana, the other two species of Lyonia occurring in the high-elevation Pinus occidentalis forests of the Dominican Republic, have been collected in the Valle Nuevo area. These hybrids are discussed in more detail in Judd (1981).

Distribution:

Dominican Republic South America| Haiti South America|