3. KALMIA L.
Trees or shrubs, with scaly bark, terete branchlets without a terminal bud, minute axillary leaf-buds, elongated axillary inflorescence-buds covered by imbricated scales, and fibrous roots. Leaves ovate-oblong or linear, short-petiolate, with flat entire margins, coriaceous, persistent or deciduous in one species. Flowers on slender pedicels bibracteolate at the base, from the axils of foliaceous coriaceous ovate or acute persistent bracts, in axillary umbels; calyx 5, rarely 6-parted, the divisions imbricated in the bud, persistent under the fruit; corolla 5, rarely 6-lobed, rose-colored, purple, or white, saucer-shaped, with a short tube and 10 pouches just below the 5 or 6-parted limb, the lobes ovate, acute, before anthesis prominently 10 or 12-ribbed from the pouches to the acute apex of the bud, the salient keel of the ribs running to the point of the lobes and to the sinuses; stamens 10, shorter than the corolla; filaments filiform; anthers oblong, each cell opening by a short apical oblong longitudinal pore, at first free in the bud, the filaments then erect, later received in the pouches of the corolla, the filaments becoming bent back by its enlargement and expansion, straightening elastically and incurving on the release of the anthers, and in straightening discharging the pollen-grains; disk prominently 10-lobed; ovary subglobose, 5-celled; style filiform, exserted, crowned with a capitate stigma; ovules numerous in each cell, inserted on a 2-lipped placenta, pendulous or spreading from near the top of the thin columella, few-ranked, anatropous. Fruit a woody many-seeded globose slightly 5-lobed 5-celled capsule, tardily septicidally 5-valved, the valves crustaceous, ultimately opening down the middle by a narrow slit and separating from the persistent placenta-bearing axis. Seeds oblong or subglobose, minute; seed-coat crustaceous or membranaceous; embryo in fleshy albumen, terete, near the hilum; radicle erect, rather shorter than the oblong cotyledons.
Kalmia with six species is North American and Cuban, one species occasionally becoming under favorable conditions a small tree.
The generic name is in honor of the Swedish traveler and botanist, Peter Kalm (1715—1779).
1. [Kalmia latifolia] L. Laurel. Mountain Laurel.
Leaves sometimes in pairs or in 3’s, conduplicate in the bud, each leaf in the bud inclosed by the one immediately below it, oblong or elliptic-lanceolate, acute or rounded and tipped at apex with a callous point, and gradually narrowed at base, rarely oval to oblong-obovate and rounded at ends (f. obtusata Rehd.), when they unfold slightly tinged with pink and covered with glandular white hairs, and at maturity thick and rigid, dark rather dull green above, light yellow-green below, 3′—4′ long and 1′—1½′ wide, with a broad yellow midrib and obscure immersed veins; beginning to fall during their second summer; petioles stout, terete or slightly flattened, about ⅔′ in length. Flowers opening from early in April in southern Mississippi to the 20th of June at the north; inflorescence-buds appearing in the autumn from the axils of upper leaves, beginning to lengthen with the first warm days of spring and usually developing 2 or several lateral branches, the whole forming a compound many-flowered corymb of numerous crowded fascicles more or less covered with dark scurfy scales, 4′—5′ in diameter, and overtopped at the flowering time by the leafy branches of the year; flowers nearly 1′ in diameter, on long slender red or green pedicels covered with glandular hairs, and furnished at base with 2 minute acute bractlets, developed from the axils of acute persistent bracts sometimes ⅓′ long; calyx divided nearly to the base into narrow acute thin green lobes; corolla white (f. alba Rehd.), rose-color, or deep pink (f. rubra Rehd.) viscid-pubescent, marked on the inner surface with a waving dark rose-colored line and with delicate purple penciling above the sacs, rarely with a broad purple or chocolate-colored band (f. fuscata Rehd.). Fruit ripening in September, crowned with the persistent style, 3/16′ in diameter, and covered with viscid hairs, remaining on the branches until the following year; seeds oblong, light brown, scattered by the opening of the valves.
A tree, rarely 30°—40° high, with a short crooked and contorted trunk sometimes 18′—20′ in diameter, stout forked divergent branches forming a round-topped compact head, and slender branchlets light green tinged with red and covered with soft white glandular-viscid hairs when they first appear, soon becoming glabrous, and in their first winter green tinged with red and very lustrous, turning bright red-brown during their second year and paler the following season, the bark then separating into large thin papery scales exposing the cinnamon-red inner bark, and marked with large deeply impressed leaf-scars showing near the centre a crowded cluster of fibro-vascular bundle-scars; more often a dense broad shrub 6°—10° high, with numerous crooked stems. Winter-buds formed before midsummer in the axils of the leaves just below those producing the inflorescence-buds, their inner scales accrescent, and at maturity often 1′ long and ½′ wide, ovate, acute, light green, covered with glandular white hairs, and in falling marking the base of the shoots with conspicuous broad scars. Bark of the trunk hardly more than 1/16′ thick, dark brown tinged with red, and divided by longitudinal furrows into narrow ridges separating into long narrow scales. Wood heavy, hard, strong, rather brittle, close-grained, brown tinged with red, with slightly lighter colored sapwood; used for the handles of tools, in turnery, and for fuel.
Distribution. New Brunswick to the northern shores of Lake Erie and southward in the Atlantic coast region to Virginia and to southern Ohio, Martin and Crawford Counties, Indiana and central Tennessee, along the Appalachian Mountains and their foothills to Georgia, and from western Florida through Alabama to eastern and southern Mississippi and the valley of the Bogue Lusa River, Washington Parish, Louisiana; often growing in low moist ground near the margins of swamps or on dry slopes under the shade of deciduous-leaved trees, or on rich rocky hillsides; most abundant and often forming dense impenetrable thickets on the southern Appalachian Mountains up to altitudes of 3000°—4000°; usually shrubby, and only arborescent in a few secluded valleys between the Blue Ridge and the Alleghany Mountains of North and South Carolina; abundant and of large size along small streams in Liberty County, western Florida. The var. myrtifolia K. Koch with small lance-oblong leaves, and small compact clusters of small flowers, a compact dwarf shrub, and an old inhabitant of European gardens, is occasionally wild in Massachusetts; in an abnormal form (f. polypetala Rehd.) found in western Massachusetts the corolla is divided into 5 narrow petals.
Often cultivated as an ornament of parks and gardens in the eastern states, and in Europe.