white clover (Trifolium repens)
Trifolium repens L. var. atropurpureum hort.
CONFIRMATION STATUS: Pending confirmation.
TAXONOMY: The currently accepted scientific name of white clover
is Trifolium repens L. This is the familiar clover in lawns with white
flowerheads. It is possible to confuse white clover with other Trifolium
spp., including the introduced Trifolium hybridum (alsike clover), native
Trifolium reflexum (buffalo clover), and native Trifolium stoloniferum
(running buffalo clover). Compared to white clover, alsike clover is a
taller and more erect plant, with flowerheads that are usually more pink,
and leaflets that are without white markings (chevrons). It doesn't form
stoloniferous stems. Similarly, running buffalo clover is a taller and more
erect plant, with flowerheads that are somewhat larger in size (often 1"
across or more), and leaflets that are also without chevrons. Running
buffalo clover is even more similar in appearance to white clover than
the others because it produces long stoloniferous stems and has flower-
heads that are about the same size and color. However, its leaves are also
without any white markings or chevrons. Both of the native clovers also
possess larger stipules (½" or longer), have slightly longer pedicels, and
have calyx teeth that are often longer than the calyx tube.
White clover exhibits a geographic polymorphism for cyanogenesis (the
release of cyanide following tissue damage, a phenomenon seen in a very
large and diverse number of plant species). Both cyanogenic and acyano-
genic plants occur in natural populations, with acyanogenic plants predom-
inating in colder climates for reasons that are not yet clear. This poly-
morphism has been studied since early in the 20th century, and represents
one of the most thoroughly studied examples of an adaptive polymorphism
in plants. Cyanogenic plants are generally found to be strongly favored in
the presence of generalist herbivores, which avoid eating them. However,
a number of costs appear to be associated with cyanogenesis, such as re-
duced drought tolerance, resulting in trade-offs that may favor cyano-
genetic or acyanogenetic plants depending on local conditions.
NATIVE STATUS: Introduced, United States and Canada.
GENERAL BOTANICAL CHARACTERISTICS:
Habit: This introduced perennial plant is about 6" tall, branching from the
base. Initially, it produces several compound leaves from a short stem that
grows only a little, after which this stem rapidly elongates and becomes up
to 1' long. These elongated stems sprawl along the ground and have the
capacity to root at the nodes. They are hairless and light green.
Leaves: The alternate compound leaves are trifoliate and hairless. They
occur at intervals along the elongated stems and have long hairless petioles.
The leaflets are obovate or ovate. Their margins are finely serrate. Across
the upper surface of each leaflet are white markings in the form of a chev-
ron (an upside down "V"), although for this species these markings are of-
ten degenerate, irregular, or absent. Each leaflet is about ¾" long and about
half as wide. At the base of each petiole there are a pair of small lanceolate stipules that are light green and membranous; sometimes they wrap around
the elongated stems. Each stipule is less than ½" in length.
Flowers: Flowerheads about ¾" across are produced on long naked stalks (peduncles) that are unbranched and hairless. These flowering stalks are
usually a little taller than the compound leaves. Each flowerhead has 20-50 flowers and is more or less globular in shape. Each flower is narrowly tub-
ular, consisting of a green calyx with 5 narrow teeth and 5 petals that are
white or pinkish white. When fully open, there is a small standard and 2
side petals that enclose the keel. The teeth of the calyx are equal to, or less
than, the length of the calyx tube. Each flower has a very short pedicel.
Fruit/Seeds: The flowers gradually turn brown and are replaced by seed-
pods. Each little seedpod contains only a few seeds, which are flat, round
or slightly heart-shaped, and variously colored.
Roots: The root system consists of a shallow branching taproot and the
rootlets formed by the elongated stems. This plant reproduces by seed or vegetatively, and often forms colonies.
REGENERATION PROCESS: White clover propogates itself by re-
seeding and vegetative horizontial expansion of elongated horizontal
HABITAT TYPES: White clover was introduced into the United States
from Europe a long time ago as a source of forage and hay. Habitats in-
clude pastures, fields, grassy meadows, lawns, parks, mowed areas along
roadsides, paths through woodlands, and waste areas. This plant prefers
disturbed areas that are grassy and subject to occasional mowing or graz-
ing. In more natural areas, it is not tall enough to be very competitive with
the native vegetation.
SITE CHARACTERISTICS: White clover thrives best in a cool, moist
climate in soils with ample lime, phosphate, and potash. In general, white
clover is best adapted to clay, loam or clay loam, and silt soils in humid
and irrigated areas. It grows successfully on sandy soils with a high water
table or irrigated droughty soils when adequately fertilized. White clover
seldom roots deeper than 2 feet, which makes it adapted to shallow soils
when adequate moisture is available. The preference is full or partial sun.
This plant fixes nitrogen into the soil.
SEASONAL DEVELOPMENT: The blooming period occurs intermit-
tently for several months, from late spring through the fall.
GENERAL DISTRIBUTION: With the exception of portions of the
Canadian northern territories, white clover is found throughout the con-
tinental United States and Canada.
SKY MEADOWS DISTRIBUTION: To be determined.
IMPORTANCE AND USES: Primarily long-tongued bees visit the
flowerheads to collect pollen or suck nectar, including bumblebees,
honeybees, mason bees, and cuckoo bees (Epeoline and Nomadine).
Other insect visitors include bee flies, thick-headed flies, white butter-
flies, and skippers. The butterflies and skippers are not effective pol-
linators of clover flowers, however. Because white clover is an impor-
tant forage crop and is used in lawns, the insects feeding on the foliage
or flowerheads are rather well known. The caterpillars of the butterflies
Everes comyntas (eastern tailed-blue), Colias cesonia (dog-faced sulfur),
Colias eurytheme (orange sulfur), and Colias philodice (clouded sulfur)
use clovers as a food source. The white clover is a preferred food source
for the caterpillars of the clouded sulfur. The caterpillars of many moths
feed on clovers, as does Frankliniella trities (flower thrip). The foliage
and seedheads are eaten by such upland gamebirds as the ruffed grouse,
greater prairie chicken, wild turkey, and ring-necked pheasant. Some song-
birds occasionally eat the seeds, including the horned lark and Smith long-
spur (winter only). Various small mammals find the foliage and seedpods
very attractive as a source of food, including the cottontail rabbit, ground-
hog, thirteen-lined ground squirrel, and meadow vole. Large hoofed animals,
such as the white-tailed deer, elk, cattle, horses, and sheep, also graze on
the foliage of clovers. If it is eaten in large amounts, however, white clover
can be toxic because it contains a glycoside that converts to prussic acid
when the foliage is eaten by animals. However, cultivated strains of white
clover have been developed that are without this glycoside. The ecological
value of white clover is not high for wildlife, it is also an important source of
honey to humans.
White clover is the most important pasture legume. It is highly palatable,
nutritious forage for all classes of livestock. White clover is commonly
planted with orchardgrass, ryegrass, or tall fescue. ‘Ladino’ planted with
orchardgrass produces the premier forage combination for intensive
grazing systems in the Northeast. ‘Ladino’ grows tall enough to be har-
vested for hay, silage, and green chop. Common white clover seldom
grows tall enough to be harvested for hay or silage.
Grass seedings benefit from the nitrogen produced by white clover included
in the seed mixture. White clover is seeded at 2 pounds per acre with grass
for stabilization on moist soils. Solid stands of white clover form a good
erosion controlling cover on moist fertile soils, but stands may be sparse or
spotty on dry sites.
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