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Piedmont rhododendron

Mt. Labrador tea, smooth Labrador tea, trapper's-tea, western Labrador tea

Habit Shrubs, to 3(–5) mm, often rhizomatous. Shrubs or trees, to 2 m, rhizomatous.
Stems

bark smooth to vertically furrowed, shredding;

twigs with ferrugineous, multicellular, broad-rimmed, glandular-peltate scales.

bark smooth, sometimes peeling or shredding with age;

twigs unicellular-hairy, papillate, with flattened, glandular scales (lepidote).

Leaves

persistent;

petiole with ferruginous, broad-rimmed, glandular-peltate scales and unicellular-hairy;

blade narrowly elliptic to elliptic or oval, sometimes obovate, (1–)5–8(–13) × (1–)2–3.5(–5.5) cm, thick, coriaceous, margins entire, plane to conspicuously revolute, with scattered, glandular-peltate scales, apex acute or acuminate or obtuse to rounded, surfaces with scattered, ferruginous, broad-rimmed, glandular-peltate scales abaxially, (scales ± deciduous adaxially).

persistent, (fragrant when crushed);

petiole with glandular-peltate scales without broad rim and few, ferruginous, long-crisped hairs;

blade (white or pale green abaxially), ovate to lanceolate, (1–)2–8 × 1.5–3 cm, coriaceous, margins entire, plane, glabrous, apex usually acute, abaxial surface sparsely to densely papillate, with few, ferruginous, long-crisped hairs and glandular-peltate scales without broad rim, adaxial surface with scattered lepidote scales and/or papillae, sometimes also unicellular-hairy along midrib.

Inflorescences

5–10-flowered;

bracts similar to bud scales.

slightly rounded, 10–35-flowered;

bracts lepidote abaxially, margins ciliate, unicellular-hairy.

Pedicels

5–15 mm, with ferruginous scales.

4–25 mm, with dense to sparse, ferruginous, long-crisped, unicellular and/or peltate scales, sometimes also long-stalked, multicellular glandular-hairy.

Flowers

opening before or after development of leaves, erect to horizontal, fragrant;

calyx lobes 0.5–2 mm, with ferruginous scales;

corolla dark to very pale pink or white, upper lobe usually with greenish spots, campanulate to funnelform, 15–37 mm, with scattered, ferruginous, peltate scales on outer surface, petals connate (for 3/4+ their lengths), lobes 8–19 mm, tube gradually expanding into lobes, 8–22 mm;

stamens 10, included to slightly exserted, ± unequal, 13–26 mm.

radially symmetric, opening after leaves (of flowering shoots), ± erect, fragrance not noticeable at mid day;

calyx lobes (often reflexed in fruit), ± 1–1.5 mm, outer surface densely to sparsely unicellular-hairy (hairs tan) and multicellular stipitate-glandular-hairy (hairs red) on margins;

corolla white to cream, without blotch, ± rotate, 2–8 mm, inner surface hairy proximally, outer surface glabrous, petals appearing distinct or only slightly connate basally, lobes (4–)5–7 mm;

stamens (8–)10(–12), exserted, ± equal, 4.5–8.4 mm.

Capsules

borne on erect pedicels, 6–14 × 2.9–5 mm, with ferruginous, peltate scales.

borne on recurved pedicels, 2.5–5 × 2–6 mm (only slightly longer than wide), glabrous, acropetally dehiscent.

Seeds

with short, blunt/truncate tails at each end;

testa closely appressed.

somewhat elongated beyond narrow ends;

testa closely appressed.

Floral

bud scales ferruginous-lepidote, sometimes also unicellular-hairy abaxially, margins unicellular-ciliate.

bud scales with peltate scales without broad rim and unicellular-hairy abaxially, margins unicellular-hairy.

2n

= 26.

= 26.

Rhododendron minus

Rhododendron columbianum

Phenology Flowering spring-mid summer.
Habitat Bogs, swamps, stream margins, sometimes on well-drained sites
Elevation 0-3500 m (0-11500 ft)
Distribution
from FNA
AL; FL; GA; NC; SC; TN
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

Rhododendron minus is here circumscribed broadly, including R. carolinianum and R. chapmanii, and the latter is considered to be a distinct variety (W. H. Duncan and T. M. Pullen 1962). Variety chapmanii is federally listed. This species is often grown as an ornamental.

Rhododendron minus and R. lapponicum are members of subg. Rhododendron, as indicated by their glandular-peltate scales; the subgenus is represented by hundreds of species in eastern and southern Asia (see J. Cullen 1980).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Leaf blades: apex usually acute or acuminate; petioles (5-)6-20 mm; branches not rigidly ascending.
var. minus
1. Leaf blades: apex usually rounded or obtuse; petioles 2-6(-7) mm; branches usually rigidly erect-ascending
var. chapmanii
Source FNA vol. 8, p. 460. FNA vol. 8, p. 459.
Parent taxa Ericaceae > subfam. Ericoideae > Rhododendron Ericaceae > subfam. Ericoideae > Rhododendron
Sibling taxa
R. alabamense, R. albiflorum, R. arborescens, R. atlanticum, R. austrinum, R. calendulaceum, R. canadense, R. canescens, R. catawbiense, R. columbianum, R. cumberlandense, R. eastmanii, R. flammeum, R. groenlandicum, R. lapponicum, R. macrophyllum, R. maximum, R. occidentale, R. periclymenoides, R. prinophyllum, R. prunifolium, R. tomentosum, R. vaseyi, R. viscosum
R. alabamense, R. albiflorum, R. arborescens, R. atlanticum, R. austrinum, R. calendulaceum, R. canadense, R. canescens, R. catawbiense, R. cumberlandense, R. eastmanii, R. flammeum, R. groenlandicum, R. lapponicum, R. macrophyllum, R. maximum, R. minus, R. occidentale, R. periclymenoides, R. prinophyllum, R. prunifolium, R. tomentosum, R. vaseyi, R. viscosum
Subordinate taxa
R. minus var. chapmanii, R. minus var. minus
Synonyms Ledum columbianum, Ledum glandulosum, R. neoglandulosum
Name authority Michaux: J. Hist. Nat. 1: 412. 1792 , (Piper) Harmaja: Ann. Bot. Fenn. 27: 203. (1990)
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