Rhodod. 229 (1917)
WFO ID: wfo-0001047080
IPNI ID: urn:lsid:ipni.org:names:219518-2
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Shrub or small tree to 3m tall, usually non-rhizomatous; young twigs red-brown, densely covered with unicellular hairs or sparsely to densely covered with multicellular eglandular hairs, rarely with multicellular gland-tipped hairs. Vegetative bud scales densely covered with unicellular hairs, rarely very sparsely covered with unicellular hairs abaxially; margin unicellular-ciliate, rarely ciliate above and glandular below. Leaf blade membranaceous, ovate or obovate to elliptic, (3.9-)5.0-7.3(-8.7) x (1.2-)1.8-3.0(-3.7)cm; base acute to oblique; apex acute to obtuse, often mucronate; adaxial surface sparsely covered with unicellular hairs or sparsely to densely covered with multicellular eglandular hairs, rarely glabrous, the midvein densely covered with unicellular hairs; abaxial surface sparsely to densely covered with unicellular hairs, rarely with scattered multicellular eglandular hairs, or densely covered with unicellular hairs and multicellular eglandular hairs, or glabrous, the midvein densely covered with unicellular and multicellular eglandular hairs, rarely with unicellular hairs and multicellular gland-tipped hairs; margin entire, ciliate with multicellular eglandular hairs; petiole (0.2-)0.3-0.5(-0.7)cm long, densely covered with unicellular hairs and sparsely to densely covered with multicellular eglandular hairs, rarely with unicellular hairs and multicellular gland-tipped hairs or glabrous. Flower bud scales chestnut brown; abaxial surface densely covered with unicellular hairs, very rarely glabrous; margin unicellular-ciliate. Flowers appearing before or with the leaves; inflorescence a shortened raceme of 4 to 13 flowers. Pedicels (0.7-)1.0-1.6(-2.6)cm long, sparsely to densely covered with unicellular hairs and multicellular eglandular and gland-tipped hairs, or with unicellular and multicellular gland-tipped hairs, rarely with unicellular hairs and multicellular eglandular hairs. Sepals less than 0.1-0.2(-0.3)cm long, often varying in length on the same flower; margins glandular-fimbriate or with both glandular and eglandular multicellular hairs, rarely only setose; abaxial surface sparsely to densely covered with unicellular hairs and multicellular gland-tipped hairs, rarely with unicellular hairs and multicellular eglandular hairs, or with only unicellular hairs or glabrous. Corolla deep- to rose-pink, rarely white, fragrance spicy, the tube longer than the limb and gradually expanding into it; upper corolla lobe (1.0-)l.l-1.6(-2.0) x (0.6-)0.8-1.2(-1.5)cm; lateral lobes (1.2-)1.4-2.0(-2.3) x (0.5-)0.6-0.9(-l.l)cm; corolla tube l.l-1.5(-1.9)cm long, (0, l-)0.2-0.3 (-0.4)cm wide at base; outer surface of corolla densely covered with unicellular hairs and multicellular gland-tipped hairs, the gland-tipped hairs continuing up the corolla lobes, rarely also with multicellular eglandular hairs; inner surface of corolla densely covered with unicellular hairs. Stamens (3.2-)3.6-4.7(-5.3)cm long, with dense terete or flattened unicellular hairs on proximal 1.2-2.4(-3.1)cm of filament, exserted (1.4-)2.0-2.8(-3.5)cm beyond throat of corolla. Style (3.2-)3.9-5.2(-5.7)cm long, exserted (2.0-)2.5-3.5(-4.3)cm beyond throat of corolla, with dense unicellular hairs on the proximal (0.0-)0.6-1.7(-2.4)cm; stigma less than 0.1-0.2cm wide. Ovary 0.2-0.4(-0.5)cm long, 0.1-0.2(-0.3)cm wide at the base, densely covered with unicellular hairs and multicellular gland-tipped hairs, occasionally also with multicellular eglandular hairs, rarely with unicellular hairs and multicellular eglandular hairs, often glabrous towards apex. Capsules (1.2-)1.3-2.0(-2.8)cm x (0.3-)0.4-0.5(-0.6)cm, ovate, narrowly ovate to cylindric, sparsely covered with unicellular hairs and sparsely to moderately covered with multicellular gland-tipped hairs. Seeds pale to dark chestnut brown, ovate or elliptic to fusiform, (1.8ó)2.3ó 3.2(-3.5) x (0.4-)0.6-l.l(-1.4)mm, body 1.0-1.4(-1.6)mm x (0.2-)0.3-0.6(-0.8)mm; testa expanded and dorsiventrally flattened, surrounding the body, the cells elongate, with tapering end-walls (Fig. 11). Chromosome number: In = 26 (Sax, 1930; JanaM-Ammal et al., 1950; Li, 1957). See Elustration in Galle, 1985 (photo).
USA: New Hampshire and Vermont south to Ashe Co., North Carolina, and to eastern Kentucky; Union Co., Illinois and south-eastern Missouri, south to Arkansas and eastern Oklahoma. Isolated populations occur in Transylvania Co., North Carolina and Cherokee Co., Alabama, and western Tennessee to Arkansas and eastern Oklahoma
Bluffs and stream banks, open wooded slopes, acid bogs
Rhododendron canescens Porter, Bull. Torrey Bot. Club. 16: 220 (1889), non R. canescens (Michx.) Sweet, Hort. Brit. ed. 2,343 (1830). Azalea prinophylla Small, N. Am. Fl. 29:42 (1914), nomen novum. Type: Pennsylvania, Monroe Co.: Pocono Summit. 22 v & 4 ix 1889, T. C. Porter s.n. (lecto., designated here, 22 v 1889, NY; isolecto. NY). Rhododendron roseum (Lois.) Rehder f. plenum Rehder, Contr. Gray Herb. 165: 10 (1947). Type: cultivated. Garden of R. H. P. Jacobus, originally found wild in the neighbouring woods. 23 vii 1935, R. H. P. Jacobus s.n. (holo. A). Rhododendron roseum (Lois.) Rehder f. albidum Steyerm., Rhodora 62: 131 (1960). Type: Missouri, Ste. Genevieve Co.: sandy pine-oak woods east of Chimney Rocks, along River Aux Vases, 5 mi E of Pickle. 24 v 1933, Steyermark 8522 (holo. MO; iso. MINN, MO)
Kron, K.A. (1993) A Revision of Rhododendron Section Pentanthera. Edinburgh Journal of Botany 50(3):323