Kalmia polifolia Wangenh. - Bog Laurel

Native , Rare

By Steven Clemants

Not peer reviewed

Last Modified 02/07/2013

Back to Kalmia

Kalmia polifolia

Common Names

Bog Laurel

Field Identification

A small shrub of bogs, with opposite, elliptic leaves and bell-shaped flowers.

Common names

Bog Laurel

Gold Withy

Pale Laurel

Swamp Laurel

Poisonous properties

Disclaimer: The information provided here is for reference and historical use. If you believe you have been poisoned, please contact the Poison Control Office near you (look for the number in the front of the phone book).

(Hardin & Arena, 1974) (Jaynes, 1975) (Lewis & Elvin­Lewis, 1977)

Bog laurel contains andromedotoxin, a toxic diterpene causing slow pulse, lowering of blood pressure, lack of coordination, convulsions, progressive paralysis, and death. Arbutin, a glycoside of hydroquinone, is also present and indicated in the poisoning.


¤Kalmia glauca Lodd., A catalogue of plants and seeds which are sold by Conrad Loddiges, London. 1777.4-1783.8. [cited by (Ludwig, 1783)]. *Kalmia glauca C. F. Ludwig, Neu. Wilde Baumz. 25. 1783, nom. inval. (Art. 34.1c). *Kalmia glauca W. Young, Cat. Arbr. Amer. 12. 1783, nom. inval. prop (Art. 32.8). *Kalmia glauca Aiton, Hort. Kew. 2: 64, t. 8. 1789. *Chamaedaphne glauca (Aiton) Kuntze, Revis. Gen. Pl. 2: 388. 1891. TYPE: No type designated, several elements, "Plants growing in the Kew gardens, (K)" according to (Ebinger, 1974).

*Kalmia polifolia C. F. Ludwig, Neu. Wilde Baumz. 25. 1783, nom. inval. (Art. 32.1c). *Kalmia polifolia Wangenh., Schriften Ges. Naturf. Freunde Berlin 8(2) (Beob. 2,2): 129, t. 5. 1788. TYPE: Type not cited, "According to Wangeheim (1987), plants growing in the Tegel Plantation, Berlin, and introduced from English gardens, were used in the original descriptions." (Southall & Hardin, 1974). The plate is probably best used as the type.

*Kalmia lanceolata Raf., Autik. Bot. 86. 1840. TYPE: United States. New Jersey: South New Jersey, 1802, collector unknown (Holotype: ?).

*Kalmia rosmarinifolia Dum.Cours, Bot. Cult. 2: 250. 1802. *Kalmia glauca var. rosmarinifolia (Dum.Cours) Pursh, Fl. Amer. Sept. 1: 296. 1814. *Kalmia polifolia var. rosmarinifolia (Dum.Cours) Rehder in Bailey, Cycl. Amer. Hort. 2: 854. 1900. TYPE: "Lieu. La Caroline. fl. en mai. Toujours vert." [leaves linear revolute with green lower surface]

*Kalmia polifolia f. leucantha Scofield & A. C. Smith, Canad. Field. Nat. 67: 94. 1953. TYPE: Canada. Newfoundland: Hodgewater Line, Trinity South, 29 Jun 1945, E. E. Smith and A. C. Smith 1055 [s.n. in protologue] (Holotype: ACAD). [white flowers]


HABIT perennial, evergreen, chamaephyte, shrubs, autotrophic, monoclinous, with adventitious roots and with fibrous roots, 0.35-1 m tall, not modified or with rhizomes.

STEMS erect, round, not winged, "regular". Prickles absent. Bark striate, not exfoliating, reddish violet or gray. Branches ascending, reddish violet or gray, round, not winged, 1 mm in diam. Twigs reddish violet, not odoriferous, elliptic, 1 mm in diam., smooth, glabrous, without glands. Pith present, yellowish orange, round, continuous. Thorns absent. Aerial roots absent. Sap translucent. Resin absent.

LEAVES opposite, 2 per node, crowded toward stem apex, divergent from stem, simple. Stipules absent. Leaves sessile. Leaf: abaxial surface yellowish green, adaxial surface green, blades linear or narrowly elliptic, revolute only at margin or revolute, symmetric, 1.2-2.8 cm long, 0.1-0.9 cm wide, coriaceous, base cuneate, margin entire, apex acute or obtuse, abaxial surface hairs long and unbranched, erect, multicellular, multiseriate, white, sparse, along midveins, glabrescent, glands present, glands at apex of hairs, orange, adaxial surface glabrous, without glands. Hyphodromous venation, veins 0. Leaf lobes absent. Spines absent. Tendrils absent.

INFLORESCENCES monomorphic, regular or, if dimorphic, female inflorescence simple, umbel, terminal. Peduncle absent. Rachis absent, with bracts. Bracts sessile, blades: abaxial surface white, adaxial surface green, lanceolate, revolute, 6-6.7 mm long, 1.5-2.2 mm wide, base obtuse, margin entire, apex acute, abaxial surface glabrous, without glands, adaxial surface glabrous, without glands. Pedicel 1.3-2.5 mm long, glabrous, without glands. Bracteoles 2, sessile, at base of pedicel, not connate, bracteoles: abaxial surface green, bracteole: adaxial surface green, obovate, curved, 2.2-3 mm long, 1.1-1.4 mm wide, base cuneate, margin ciliate, apex obtuse, 3. Cupules absent.

FLOWERS serotinous, formed on long shoots, monomorphic, with sepals and petals readily distinguishable from one another, bisexual. Perfect or female flowers red, 5-merous, 5-6 mm long, 9-14 mm wide, 6-9 flowers per inflorescence, perianth of two whorls. Calyx present, actinomorphic, crateriform, of free sepals, persistent, abaxial and adaxial surfaces the same color, orange, 3.5-3.7 mm long, 2.5-4.2 mm wide. Sepals or sepal lobes 5, ovate or widely ovate or very widely ovate, 1.7-2.5 mm long, 1.4-2.1 mm wide, base truncate, margin ciliate, apex obtuse, abaxial surface glabrous, without glands, adaxial surface glabrous, without glands. Epicalyx absent. Corolla present, actinomorphic, acetabuliform, of fused petals, deciduous, abaxial and adaxial surfaces the same color, red, 5-6 mm long, 9-14 mm wide, corolla limb 4.5 mm long, 9.5 mm wide. Petals or petal lobes 5, "normal", shallowly triangular, 2.9-3 mm long, 5-5.4 mm wide, base truncate, margin entire, apex acute, abaxial surface glabrous, without glands, adaxial surface glabrous, without glands. Gynoecium syncarpous. Carpels 5. Stigmas 1, lobed, flat, 5-lobed. Styles persistent, 1, 6.7-7.2 mm long. Ovary superior, 1.1-1.9 mm long, 1.4-2.1 mm wide, nectiferous disk present. Locules 5. Placentation axile. Androecium obdiplostemonous. Stamens 10, 4.8-5 mm long. In pockets on the corolla. Anthers oblong, opening by pores, bithecal, red, glabrous. Filaments free, straight, red, hairs short and unbranched, erect, unicellular, uniseriate. Staminodes absent.

FRUITS septicidal capsule, violet-red, globose, 3.5-4.3 mm long, 3.7-4.8 mm wide, glabrous, without glands.

SEEDS many, yellow, irregularly oblong, 1.5 mm long, 0.3 mm wide, wingless, tailed, lineate.


(Wherry, 1920)

Bog mats and pine swamps. pH 4.5-5.

Rarity Status

Heritage global rank -- G5

Connecticut -- not listed

New Jersey -- endangered (Heritage rank: S1)

New York -- not listed

Species Biology


May [week 4].


(Jaynes, 1968) (Reader, 1975) (Reader, 1977)

Autogamy -- Autogamy is possible but usually not very effective.

Melittophily -- Flowers are visited most commonly by Andrena vivina Sm., Apis melifera L., Colletes inaegualis Say., B. affinis Cr., B. bimaculatus Cr., B. borealis Kby., B. fervida (F.), B. griseocollis (DeG.), B. impatiens Cr., B. ternarius Say, Bombus terricola Kby., and B. vagans Sm.


(April [week 4]) June [week 3] - July [week 2] (Aug [week 2]).


Anemochory -- Probably wind-dispersed.


(Jaynes, 1982) (Jaynes, 1988)

Germinable -- No dormancy; temperature for initial growth is 70°-75°F.

Light required.