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Published In: Rhododendrons in which is set forth an account of all species of the genus Rhododendron (including Azaleas) and the various hybrids 229. 1917. (Rhododendrons) Name publication detail
 

Project Name Data (Last Modified On 8/11/2017)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Native

 

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1. Rhododendron prinophyllum (Small) Millais (roseshell azalea, mountain azalea, wild honeysuckle, election pink)

Azalea prinophylla Small

R. roseum (Loisel.) Rehder

R. roseum f. albidum Steyerm.

R. canescens Porter (1889), not (Michx.) Sweet (1830)

Pl. 375 h–j; Map 1644

Plants shrubs or small trees, not colonial. Stems 0.8–3.0 m tall, the bark dark gray, often becoming scaly with small plates. Twigs densely and often minutely hairy, reddish brown, becoming brown to dark gray, the winter buds ovoid, with several overlapping scales, these sparsely and minutely hairy on the outer surface. Leaves tending to be clustered near the branch tips, short-petiolate. Leaf blades 4–9 cm long, 2–4 cm wide, ovate to obovate, the margins entire and short-hairy, sparsely hairy on both surfaces, the main veins of the undersurface densely hairy. Inflorescences short, umbellate racemes of 4–13 flowers, appearing before or with the leaves. Flowers slightly zygomorphic, hypogynous, fragrant. Calyces deeply 5-lobed, 1.0–1.5 mm long, the lobes rounded to bluntly pointed at the tip, densely glandular-hairy. Corollas trumpet-shaped, the tube 1.2–1.8 cm long, flaring to spreading lobes 1.1–1.6 cm long, rosy pink or rarely white, the outer surface moderately to densely glandular-hairy. Stamens 5, exserted, the filaments 4.0–4.5 cm long, arched upward, hairy toward the base, lacking spurs near the anther-filament junction, the anthers tiny, ovate, lacking tubes or awns at the tip, dehiscing by 2 terminal pores. Ovary superior, densely glandular-hairy, with 5 locules, the placentation axile. Style 4–6 cm long, arched upward or slightly S-shaped, exserted to slightly beyond the stamens, mostly not persistent at fruiting, the stigma obconic to disk-shaped, shallowly 5-lobed. Fruits capsules, 10–14 mm long, 3–5 mm wide, narrowly oblong-ovoid to cylindrical, sparsely to densely glandular-hairy, dehiscing longitudinally from the tip along the sutures. Seeds 2.0–3.5 mm long, 0.6–1.0 mm wide, irregularly ovate to elliptic, strongly flattened and irregularly winged, the wing more or less entire at the tip and more or less fringed or dissected at the base, the surface more or less smooth, yellowish brown to light brown, shiny. 2n=26. April–May.

Scattered and local in southeastern Missouri and the southern portion of the Ozark Division (eastern U.S. and adjacent Canada west to Missouri, Oklahoma, and Texas). Mesic upland forests and ledges of bluffs, mostly on north-facing exposures and acidic substrates.

This species has a disjunct distribution, occurring mainly in the Appalachians and the Ozarks. Overall, plants in the western part of the range tend to have longer corolla tubes than those in the eastern portion, but a number of exceptions are known from each region (Kron, 1993). This species was known as R. roseum in much of the older literature (Steyermark, 1963), however that name was not validly published (Shinners, 1962; Kron, 1989).

The morphologically similar R. canescens (Michx.) Sweet (Piedmont azalea) is relatively widespread in the southeastern United States and has been documented from Union County, Illinois (adjacent to Cape Girardeau County, Missouri), as well as from several counties in western Kentucky and Tennessee. It differs from R. prinophyllum in its shorter and usually glandless flower stalks, narrower corolla tube expanded more abruptly into the lobes, and hairy fruits (Kron, 1993). This species can easily be mistaken for R. prinophyllum and may eventually be located in Missouri.

 
 


 

 
 
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