''Polygala lewtonii'' is a rare species of flowering plant in the milkwort family known by the common name Lewton's polygala, or Lewton's milkwort. It is endemic to Florida in the United States, where it is limited to the central ridge of the peninsula. There are about 49 occurrences of the plant remaining.USFWS
''Polygala lewtonii'' Five-year Review.
August 2010. Most occurrences contain very few plants. The species is threatened by the loss and degradation of its habitat.''Polygala lewtonii''.
The Nature Conservancy. This is a federally listed

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

of the United States.

Description

The plant is a short-lived perennial herb producing erect, fleshy stems from the top of its taproot. The stems grow up to 20 centimeters tall. The leaves are alternately arranged and overlapping, with a number of small leaves in the axil of one larger leaf. They are linear to spatula-shaped and about a centimeter long. The top of each stem is occupied by a short inflorescence of flowers. There are three types of flowers on this plant. The most obvious is the chasmogamous type borne in the inflorescence on the stem. These are each half a centimeter long with pink winglike sepals and three smaller tufted pink petals at the center. The second type of flower is cleistogamous and borne at the base of the plant. These do not open, but

self-pollinate Self-pollination is a form of pollination in which pollen from the same plant arrives at the stigma of a flower (in flowering plants) or at the ovule (in gymnosperms). There are two types of self-pollination: in autogamy, pollen is transferred t ...

. These flowers, which occur at the leaf axils, are rare.Weekley, C. W. and A. Brothers. (2006)
Failure of reproductive assurance in the chasmogamous flowers of ''Polygala lewtonii'' (Polygalaceae), an endangered sandhill herb.
''Am J Bot'' 93:245-53. The third type of flower is a cleistogamous, unopening type that remains underground. These are borne on a stalk up to 40 centimeters long which is located just below the surface of the soil. They are white in color, and also self-pollinate. The very uncommon mode of reproduction characterized by aboveground chasmogamous flowers and belowground cleistogamous flowers is called amphicarpy and it is known from fewer than 100 plant species. The different types of flowers may occur at different times of the year. The aboveground flowers depend on insect

pollinator A pollinator is an animal that moves pollen from the male anther of a flower to the female stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insects are the maj ...

s for successful reproduction, as evidenced by the low fruit production of flowers in a pollinator-exclusion experiment. Pollinators include

bee-flies The Bombyliidae are a family of flies, commonly known as bee flies. Adults generally feed on nectar and pollen, some being important pollinators. Larvae are mostly parasitoids of other insects. Overview The Bombyliidae are a large family o ...

, flower flies, and leaf-cutter bees. The fruit is a capsule containing cylindrical seeds each about 0.3 centimeters long. The seeds have hairs which attract ants, which then collect and disperse them. The most common type of seed-collecting ant is '' Pheidole morrissii'' and others include '' Paratrichina arenavaga'' and '' P. phantasma''.

Distribution

This plant grows on the sandhills of Central Florida and the transition between sandhill and Florida scrub. The land is dominated by longleaf pine, turkey oak, and other oaks. It can also be found in recently cleared areas such as the dry, open clearings around power lines. The substrate is yellow sand. Other endangered plant species in the habitat include '' Warea amplexifolia'', '' Ziziphus celata'', ''

Prunus geniculata ''Prunus geniculata'' is a rare species of plum known by the common name scrub plum. The species is endemic to Florida. Description This plant is a low, rounded shrub with a gnarled trunk emerging from the sand and branching densely to form a ...

'', and '' Nolina brittoniana''.''Polygala lewtonii''.
Center for Plant Conservation.

Habitat

The habitat occupied by this plant is maintained by a natural fire regime. Fire helps the plant by removing competing plants and the buildup of ground litter and

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fer ...

of seeds in the soil seed bank. Fire also benefits the plant by increasing its survival, lowering its age of reproductive maturity, and increasing the density of the plants. Because fire is beneficial and necessary for the plant, the common practice of fire suppression is a major threat to its survival. The plant declines the longer its habitat goes without a fire. Another major threat to the species is the outright loss of its habitat to development. The yellow-sand sandhill regions are desirable for conversion to citrus groves. Land has also been consumed in rapidly expanding development of residential areas. The destruction of the habitat has resulted in

habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes ...

. Remaining fragments are popular terrain for off-road vehicle enthusiasts. Many occurrences of the plant are located on land that is now protected. Prescribed burns help to bring the habitat back to its normal state.

References

{{Taxonbar, from=Q7226326 lewtonii Endemic flora of Florida