20T 



MOUNTAIN LAUREL. 



Kalmia latifolia, Linnaeus. 



FAMILY AND GENUS DESCRIPTION The Heath family, Ericaceae, embraces species which 

 are amongst our best known and most popular shrubs. The Buckle-berries, Blueberries, Cran- 

 berries, Azaleas, Kalmlas, and Rhododendrons are some of the commonest representatives. 

 Very few representatives are of any special economic value on account of the wood which 

 they produce. Some are Important on account of their aesthetic value, while others yield 

 valuable food or are used In medicine. This family comprises about 90 genera with more 

 than 1,400 species, of which number about 40 genera are found in the United States, 7 of which 

 have tree representatives. The flora of Pennsylvania comprises 27 genera with about 45 species. 

 Since most of them are shrubs only 8 species representing 3 genera are described here. The 

 genera here described are Kalmia, Rhododendron, and Oxydendrum. 



The genus Kalmia comprises 5 or 6 species in North America and Cuba. The species 

 described on this page is the only 4>ne which reaches tree-size. Two other shrub species, Sheep 

 Laurel (Kalmia angustifolia L.) 'and Swamp Laurel (Kalmia polifolia Wang.), are also 

 native to this State. The genus is named after Peter Kalm, a Swedish naturalist, who 

 traveled in North America during the middle of the 18th century. 



FORM In Pennsylvania usually a shrub 5-10 ft. in height with a stout stem which is 

 usually forked, often inclined and bearing divergent branches which form a round compact 

 head. In the South it reaches a height of 30-40 ft. with a diameter of 20 inches. 



BARK Very thin, reddish-brown, furrowed, peels off into long, narrow, thin scales ex- 

 posing cinnamon-red inner bark. 



TWIGS At first reddish-green covered with viscid hairs, later becoming decidedly green, and 

 finally brown. Rather smooth except where roughened by leaf-scars and bud-scale scars. 



BUDS Alternate, ovate, sharp-pointed, greenish in color. Leaf-buds are formed early and 

 appear below the clustered flower-buds. Flower-buds are covered by numerous, downy and over- 

 lapping green scales which arc coated with glandular hairs and enlarge with the developing 

 shoot in spring. 



LEAVES Alternate, sometimes paired, simple, oblong, wedge-shaped at base, entire- 

 margined, acute at apex sometimes tipped with bristle point, 3-4 inches long, about i of an inch 

 wide. Mature leaves are thick, leathery, dark green, glossy above, yellowish-green below, 

 and persist for two seasons. 



LEAF-SCARS Large, imbedded in twig, with a cluster of bundle-scars. 



FLOWERS Emerge from flower buds which begin to expand hi early spring and open about 

 May or June. Flowers are borne on red or groen scurfy stalks and arranged in dense many- 

 flowered corymbs which have a diameter of about 4 inches. Calyx is divided into five parts. 

 Corolla is white to rose-colored and viscid pubescent. 



FRUIT Matures about September. It is a many -seeded woody capsule, roundish in outline 

 but slightly five-lobed and covered with viscid hairs. Both style and calyx persist. Each 

 capsule produces many seeds. 



WOOD Diffuse-porous; heavy, hard, strong, rather brittle. Heartwood reddish-brown, 

 sapwood lighter colored. Weighs 44.62 Ibs. per cubic foot. Where it grows to a fair size 

 it is an excellent wood for fuel. It is also used in manufacture of tool handles, penholders, 

 bucket handles, turnery, and tobacco pipes. About 85,000 Ibs. of this wood are produced 

 annually in North Carolina for pipes. 



DISTINGUISHING CHARACTERISTICS The Mountain Laurel, also known as Kalmia and 

 Calico-Bush, is one of our few broad-leaved species whose leaves persist over winter. It can 

 be distinguished from all other species native to this State by its thick leathery leaves which 

 are 3-4 inches long, persistent, decidedly glossy on upper surface and yellowish-green on 

 lower surface. The Great Laurel or Rhododendron is also evergreen but its leaves and buds are 

 much larger than those of the Mountain Laurel. The leaves of the Mountain Laurel are 

 shorter, narrower, and sharper-pointed than tnose of the Rhododendron. 



RANGE New Brunswick south generally along the mountains to Florida, west to Arkansas. 



DISTRIBUTION IN PENNSYLVANIA Throughout the State. Most common In the moun- 

 tainous parts, where it often forms almost impenetrable thickets. Very rare and local, or absent, 

 in the extreme western part. 



HABITAT Common along margins of swamps and as an understory in deciduous forests. 

 Also found on hillsides and hilltops. Very common on rocky and round hilltops. 



IMPORTANCE OF THE SPECIES The Mountain Laurel remains too small in this State 

 to be of commercial importance on account of the wood which It produces. Next to Rhodo- 

 dendron, it is the most attractive native shrub found in our flora. It is a favorite with lovers 

 of the woods who admire not only Its blossoms, brt also its leaves and its habit of growth. 



