Summary ⁴

Kalmia latifolia, commonly called mountain-laurel,calico-bush, or spoonwood, is a species of flowering plant in the blueberry family, Ericaceae, that is native to the eastern United States. Its range stretches from southern Maine south to northern Florida, and west to Indiana and Louisiana. Mountain-laurel is the state flower of Connecticut and Pennsylvania. It is the namesake of the city of Laurel, Mississippi (founded 1882).

Barcode data: kalmia latifolia ⁵

The following is a representative barcode sequence, the centroid of all available sequences for this species.

Habitat characteristics ⁶

More info for the terms: density, mesic, tree, xeric

Soil:
Mountain-laurel occurs commonly on xeric sites with rocky or sandy acidic soils on
southern-facing slopes, ridges, and mountain hillsides [8,40,75,81,94,108,134],
although it occasionally occurs on well-drained mesic floodplain soils
[135]. Mountain-laurel may be less abundant or entirely absent on northerly-facing
mesic slopes or along stream bottoms [84]. Mountain-laurel forms dense, almost impenetrable
patches known locally as "laurel hells" or "ivy thickets," on upper
slopes and ridges where tree canopy may be sparse or lacking [60,84]. These sites are
characterized by steep rocky slopes, high solar radiation, and acidic sandy soils
containing low amounts of organic matter [36,84,94,108,134]. In the southern Appalachian
Mountains mountain-laurel occurs more frequently on sites with a thin A soil horizon
layer [82]. Where mountain-laurel is common, soil nutrient levels and water availability
are generally low [64,82]. The following table shows average soil chemical and physical
properties from a southern Appalachian xeric oak-pine forest [64].N (%)C (%)pHOrtho-p (mg kg-1)Ca (mg kg-1)K (mg kg-1)Mg (mg kg-1)Bulk density (g cm-3)0.13.33.91.72861190.75

Mountain-laurel foliage litterfall contributes nutrients back to forest soil [101].
The following table shows estimated average mountain-laurel foliage
nutrient concentration percent.Lignin (%)Ca (%)Mg (%)P (%)K (%)21.51.58%0.18%0.01%0.30%


Mountain-laurel is dependent on mycorrhizal fungus associated with its root system
in the soil, which ensures adequate absorption of water and minerals even in areas of
nutrient-poor, acidic soil [60].

Climate:
Considerable climatic diversity is found throughout mountain-laurel's range. In general,
temperature, precipitation, and length of growing season increase from north to south.
However, a wide variety of local microclimatic conditions exist in the complex topography
of the Appalachian Mountain region. Habitats that include mountain-laurel endure climate
ranging from subtropical along coastal plains to temperate further inland. Seasonal weather
patterns are driven by alternating cold/dry continental air masses from Canada and warm/moist
air from the Gulf of Mexico. Precipitation is generally distributed uniformly throughout the
year mostly as rain, while snow and ice are common in the winter months, especially in
mountain-laurel's northern range and higher mountainous terrain. Mean annual precipitation
ranges from 39 to 78 inches (1000-2000 mm). Depending on location, annual snow accumulations
range from 8 to 48 inches (200-1220 mm). Tropical cyclones are possible throughout the summer
and fall months and can result in very high amounts of precipitation and wind [20,44,103,105].

Annual average precipitation for select locations are: StateLocationMean Annual PrecipitationCitationNCCoweeta71.3 inches (1810 mm)[9]KYStanton44.5 inches (1130 mm)[8]TNCleveland53.2 inches (1350 mm)[55]

Seasonal variations in temperature increase away from the coast. Average winter
temperatures vary from 10°F (-12°C) in the north to 64°F (18°C) in mountain-laurel's
southern range. Average summer temperatures are less variable, ranging from 70° to 72 °F
(21° to 22 °C) [20,44,103].

Importance to livestock and wildlife ⁷

Mountain-laurel's
leaves, buds, flowers and fruits are poisonous and may be lethal to livestock
and humans [4,77]. However, white-tailed deer,
eastern cotton tails, black bear, and ruffed grouse are known to
utilize this species especially as winter forage or during years of food
shortages [30,48,60,61,69,109,110,118].

Palatability/nutritional value:

Nutritional values of mountain-laurel foliage were analyzed 10 to 12 months after spring
burning and in adjacent unburned stands in northeastern Georgia. The
authors [109] believed that their methodology underestimated crude fat
values. Percent composition of mountain-laurel foliage before and after
burning follows:

 UnburnedBurnedMoisture52.556.5Crude protein8.29.9Crude fat2.51.9Crude fiber14.713.7Nitrogen (free extract)71.070.9Ash3.63.6Calcium0.870.79Phosphorus0.1160.139

Cover value: Animals that associate with mountain-laurel include white-tailed
deer, eastern screech owl, black bear, ruffed grouse, and various song
bird species [104,109,110]. Black
bears are known to den in "ground nests" in
mountain-laurel thickets [122].

Key plant community associations ⁸

More info for the terms: codominant, fern, fire suppression, hardwood, heath, lichens, marsh, mesic, shrub, shrubs, tree, vines, xeric

Mountain-laurel occurs in the understory of a variety of habitat types and plant
communities throughout eastern North American. It may be found within many plant
associations of the southern and Mid-Atlantic states. While not intended
as an exhaustive or definitive list, the following are specific examples of
communities in which mountain-laurel can be found.

Mountain-laurel is found in openings or open stands of spruce-fir (Picea-Abies
spp.) forests in the central and southern Appalachian arboreal highlands, mountain
tops, and "balds" (see below) [16]. These types of forest are dominated by red
spruce (P. rubens) but may coalesce with mixed hardwood or northern hardwood
forests on lower slopes. Common overstory associates include Fraser fir (A. fraseri),
yellow buckeye (Aesculus flava), sweet birch (Betula lenta), and black cherry
(Prunus serotina) [38,41]. Common understory associates include rhododendrons
(Rhododendron spp), American mountain-ash (Sorbus americana), and possumhaw
(Viburnum nudum var. cassinoides) [2,66,111]. Other understory associates
include highbush cranberry (V. edule), mountain holly (Ilex montana), speckled
alder (Alnus rugosa), pin cherry (P. pensylvanica), serviceberry (Amelanchier spp.),
raspberries (Rubus spp.), blueberries (Vaccinium spp.), and huckleberries
(Gaylussacia spp.) [100,128]. In closed red spruce stands, mosses, lichens, and
clubmosses (Lycopodium spp.) dominate the understory along with other shade tolerant
species such as wood sorrel (Oxalis spp.), trillium (Trillium spp.), and
wintergreen (Gaultheria procumbens) [127].

Heath "balds" that form along the tops of the highest (>4000 feet
(1200 m)) southern and central Appalachian mountain peaks are dominated by dense thickets
of ericaceous shrubs. Mountain-laurel is a dominate species of these habitats or may
co-dominate with Catawba rosebay (Rhododendron catawbiense) at subxeric/submesic
ecotones [16,128]. However, a considerable difference in the distribution of these 2
species is present over an elevational gradient. Mountain-laurel tends to favor the
lower elevation balds whereas above 6000 feet (1800 m), where the highest balds exist,
Catawba rosebay is common [4,5,9,17]. Common shrub associates include Catawba rosebay,
black chokeberry (Photinia melanocarpa), mountain sweetpepperbush (Clethra acuminata),
highbush blueberry (Vaccinium corymbosum), mountain holly, possumhaw, blackberries,
and American mountain-ash. Herbaceous abundance is limited by these dense thickets [44,100,127].

Mountain-laurel is a common understory component of northern hardwood forests.
These forests are generally found at middle to high elevations in the central and
northern Appalachian Mountains, often transitioning to spruce/fir or mixed
hardwood forest at higher or lower elevations, respectively [103,111,128]. Common
overstory tree species include sugar maple (Acer saccharum), basswood
(Tilia americana), yellow birch (B. alleghaniensis), black cherry,
red spruce, white spruce (Picea glauca), American beech (Fagus grandifolia),
eastern white pine (Pinus strobus), eastern hemlock (Tsuga canadensis),
northern red oak (Quercus rubra), white oak (Q. alba), and yellow-poplar
(Liriodendron tulipifera) [100,103]. Understory associates include beaked hazel
(Corylus cornuta), eastern leatherwood (Dirca palustris), red elderberry
(Sambucus racemosa var. racemosa), alternate-leaf dogwood (Cornus alternifolia),
bush-honeysuckle (Diervilla lonicera), Canada yew (Taxus canadensis),
red raspberry (Rubus idaeus), and blackberries. Carolina springbeauty
(Claytonia caroliniana), snow trillium (Trillium grandiflorum), anemone
(Anemone spp.) marsh blue violet (Viola cucullata), downy yellow violet
(V. pubescens), hairy Solomon's seal (Polygonatum pubescens), starry
Solomon's-seal (Maianthemum stellatum), hairy sweet-cicely
(Osmorhiza claytonii), adderstongue (Ophioglossum spp.), Jack-in-the pulpit
(Arisaema triphyllum), bigleaf aster (Eurybia macrophylla), and
clubmosses [103,127].

Mountain-laurel is an understory species associated with mixed hardwood forest. This
habitat occurs on rich, mesic sites, on sandy plains, rock outcrops, and at the outer edges
of floodplains east of the Mississippi. These forests often support a high level of plant
diversity [89,107,111]. Overstory associates of mountain-laurel are numerous and include northern
red oak, white oak, black oak (Q. velutina), scarlet oak (Q. coccinea), southern
red oak (Q. falcata), post oak (Q. stellata), yellow-poplar, eastern white pine,
American beech, sugar maple, red maple (Acer rubrum), black cherry, American basswood,
sweetgum (Liquidambar styraciflua), white ash (Fraxinus americana), green ash
(F. pennsylvanica), aspen (Populus tremuloides), hickories (Carya spp.),
black tupelo (Nyssa sylvatica), black walnut (Juglans nigra), jack pine (Pinus
banksiana), eastern hemlock [56], and elm (Ulmus spp.) [12,79,128]. Common mid-canopy
tree associates include flowering dogwood (Cornus florida), holly (Ilex spp.),
eastern hophornbeam (Ostrya virginiana), sassafras (Sassafras albidum), American
bladdernut (Staphylea trifolia), eastern redbud (Cercis canadensis), common persimmon
(Diospyros virginiana), and serviceberry. Common understory shrubs and vines include
greenbrier (Smilax spp.), blueberries, rosebay rhododendron (Rhododendron maximum),
eastern leatherwood, witch-hazel (Hamamelis virginiana), beaked hazel, spicebush
(Lindera benzoin), poison-ivy (Toxicodendron radicans), and grape (Vitis spp.) [6,100].

Mountain-laurel is the primary understory species of xeric pine (Pinus spp.)
-hardwood forest. This forest type is common on southerly facing
slopes in the southern and central Appalachians, adjacent foothills, piedmont,
and coastal plains. These forests are thought to be highly dependent on moderate- to
high-intensity fires [112]. However fire suppression, drought-induced insect infestations,
and logging have promoted the dominance of hardwood species and dense thickets of mountain-laurel
in later-successional stands [110,111]. Early-successional stands are dominated by pitch pine
(P. rigida), Table Mountain pine (P. pungens), and/or Virginia pine
(P. virginiana) [10,29]. As stands mature, other associated tree species
arrive [86] and include chestnut oak (Q. prinus) [27,28], white oak, bear oak
(Q. ilicifolia), blackjack oak (Q. marilandica), chinkapin oak
(Q. muehlenbergii), post oak, black oak, shortleaf pine (P. echinata),
scarlet oak, red maple, black tupelo, sourwood (Oxydendrum arboreum), American chestnut
(Castanea dentata), black locust (Robinia pseudoacacia), hickories, and
sassafras [14,86,93,107]. Associated shrub species include downy serviceberry (Amelanchier arborea),
coastal sweetpepperbush (Clethra alnifolia), black huckleberry (G. baccata), dwarf
huckleberry (G. dumosa), blue huckleberry (G. frondosa), sheep-laurel
(Kalmia angustifolia), wintergreen, fetterbush (Leucothoe racemosa), maleberry
(Lyonia ligustrina), piedmont staggerbush (L. mariana), bayberry (Morella spp.),
black chokecherry, black cherry, flameleaf sumac (Rhus copallinum), cat greenbrier
(Smilax glauca), roundleaf greenbrier (S. rotundifolia), Virginia tephrosia
(Tephrosia virginiana), low sweet blueberry (Vaccinium angustifolium), and hillside
blueberry (V. pallidum) [5,17,57,130].

Mountain-laurel is a common understory species of oak (Quercus spp.)-hickory
forests in the southern and east-central United States. Oak-hickory forests
are found on sand deposits and on dry upper slopes, ravines, and ridges of
southerly or westerly aspects [100]. This type of forest covers approximately 127
million acres (51 million ha) or 34% of the forests in the eastern U.S. Oak-hickory
forest dominates the east-central U.S. but gives way to mixed hardwoods to the north
and in the higher terrain of the Appalachian Mountains, and to pine-hardwood forest to
the south [110]. Dominant overstory associates include blackjack oak, post oak, northern
red oak, white oak, black oak, scarlet oak, southern red oak, and turkey oak (Q. laevis).
Other overstory associates include pignut hickory (C. glabra), black hickory, mockernut
hickory (C. tomentosa), shingle oak (Q. imbricaria), winged elm
(U. alata), black tupelo, and sourwood [12,111,128]. Understory tree and shrub
associates include flowering dogwood, blueberries, huckleberries, and sumac (Rhus spp.).
Herbaceous plant associates include bluestems (Andropogon spp.), little bluestem
(Schizachyrium scoparium), and various sedges (Carex spp.) [14,100].

Mountain-laurel is an understory associate of eastern white pine forests.
These forests occur on a variety of sites along a moisture gradient from wet bogs
and moist stream bottoms to xeric sand plains and rocky ridges. Eastern white pine
often forms pure stands but more frequently occurs as a codominant or associate of
northern hardwood or mixed hardwood forest types containing northern red oak and/or
red maple [111]. In the northern range of this species through Maine and New Brunswick,
eastern white pine forests occur on mesic sites along or near bogs. In the southern and
central Appalachian Mountains, pure stands mainly occur on northerly aspects, in coves,
and on stream bottoms [100]. Due to the large amount of shade in the understory of
these forests, herbaceous and shrub species are scarce in pure stands of eastern
white pine. On dry sites where stand densities may allow more light, mountain-laurel's
understory associates include blueberry, wintergreen, bush-honeysuckle, sweet fern
(Comptonia peregrina), western bracken fern (Pteridium aquilinum),
clubmoss, and broomsedge bluestem (A. virginicus) [6,26]. On moist rich sites,
associates include mountain woodsorrel (Oxalis montana), partridgeberry (Mitchella
repens), wild sarsaparilla (Aralia nudicaulis), Jack-in-the-pulpit, and
eastern hayscented fern (Dennstaedtia punctilobula). Herbaceous
associates include bigleaf aster, wild lily-of-the-valley (Maianthemum
canadense), and bunchberry (Cornus canadensis) [103,125].

Mountain-laurel commonly occurs in the understory of oak-pine forest.
These forests are found along the Atlantic and Gulf coastal plains, piedmont,
and floodplains. Pines may make up 25% to 50% of the composition of these
forests [126]. Common overstory associates include shortleaf pine, loblolly pine
(P. taeda), scarlet oak, southern red oak, water oak (Q. nigra),
willow oak (Q. phellos), black tupelo, sweetgum, Table Mountain pine, mockernut
and pignut hickories, winged elm, sourwood, red maple, American beech, and Carolina ash (F.
caroliniana). Common understory woody species include flowering dogwood, redbud, and
common persimmon [20,91,100,110,111].

Mountain-laurel frequently occurs in "pine barren or plain"
communities of the New Jersey and New York coastal plains [132]. These habitats
have a limited distribution of fire-dependent habitats ranging from pine forests to
dwarfed (< 10 feet (3.0 m) tall) shrubland communities [88]. Dominant overstory
species include pitch pine and other tree species such as blackjack oak, bear oak,
shortleaf pine, and dwarf chinquapin oak (Q. prinoides). Shrub associates
include black huckleberry, hillside blueberry, dangleberry (Gaylussacia frondosa),
piedmont staggerbush, and highbush blueberry  [20,43,57,78,129].

Mountain-laurel is an occasional understory species in upland and mesic sites within
longleaf pine (P. palustris) forests and savannas. The fire
dependent forests dominated by longleaf pine are located in and along the
Atlantic and Gulf coastal plains and lower Piedmont regions of Georgia
and Alabama [91]. Associated species on mesic coastal plain sites include southern
red oak, blackjack oak, water oak, flowering dogwood, black tupelo, sweetgum, persimmon,
and sassafras. Associated species on xeric sandhill sites include turkey oak, bluejack oak
(Q. incana), and live oak (Q. virginiana). Associated shrubs include inkberry
(I. glabra), yaupon (I. vomitoria), large gallberry (I. coriacea),
southern bayberry (Myrica cerifera), blueberries, huckleberries, blackberries,
saw-palmetto (Serenoa repens), sweetbay (Magnolia virginiana), cyrilla
(Cyrilla racemiflora), and buckwheat tree (Cliftonia monophylla). In longleaf
pine's western range, groundcover includes bluestems and panicums (Panicum spp.).
In its eastern range, pineland threeawn (Aristida stricta) is the primary
groundcover [20,92,100].

Classifications describing plant communities in which mountain-laurel is a
dominant species are as follows:
North Carolina [11,16,82,100]

South Carolina [1]

Tennessee [11,16,100]

West Virginia [46]

Virginia [16,46,100]

Blue Ridge Mountains [80]

Sources and Credits

1. (c) Martin LaBar, some rights reserved (CC BY-NC), https://www.flickr.com/photos/martinlabar/3791749950/
2. (c) Nemo's great uncle, some rights reserved (CC BY-NC-SA), http://www.flickr.com/photos/71453924@N00/2520352425
3. (c) Steven J. Baskauf, some rights reserved (CC BY), http://bioimages.vanderbilt.edu/baskauf/18375
4. Adapted by Jonathan (JC) Carpenter from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Kalmia_latifolia
5. (c) Barcode of Life Data Systems, some rights reserved (CC BY), http://eol.org/data_objects/30711680
6. Public Domain, http://eol.org/data_objects/24636732
7. Public Domain, http://eol.org/data_objects/24264576
8. Public Domain, http://eol.org/data_objects/24636728

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