''Leavenworthia'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of flowering plants in the family Brassicaceae. It includes about eight species native to the southern and southeastern United States.''Leavenworthia''.
Flora of North America. They are known generally as gladecresses.''Leavenworthia''.
USDA PLANTS.''Leavenworthia''.
Integrated Taxonomic Information System (ITIS).

Description

These are small annual herbs under 10 centimeters tall.Beck, J. B., et al. (2006)
''Leavenworthia'' (Brassicaceae) revisited: testing classic systematic and mating system hypotheses.
''Systematic Botany'' 31(1), 151-59. They produce a basal rosette of leaves and often lack a true stem, instead sending up a scape, a flowering stalk topped with an

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

. The inflorescence is usually made up of just one flower, but a large plant may produce several flowers in a

raceme A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...

. The petals are white, yellow, orange, or lavender. They are often notched and clawed, narrow at the base and wider at the tip. There are six

stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filame ...

s, two short and four long. The fruits are siliques or silicles of various shapes. The seeds are flattened and have wide margins or wings.

Ecology

''Leavenworthia'' species are mainly restricted to habitats with

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

substrates, especially cedar glades.Baskin, J. M. and C. C. Baskin. (1978)
The rarity of ''Leavenworthia uniflora'', with special reference to its occurrence in Kentucky.
''Castanea'' 43(1) 54-57. These glades can be very wet in winter and spring, even flooded. Several species are narrow

endemics Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

in terms of geography; ''L. alabamica'' and ''L. crassa'' are endemic to

Alabama (We dare defend our rights) , anthem = "Alabama (state song), Alabama" , image_map = Alabama in United States.svg , seat = Montgomery, Alabama, Montgomery , LargestCity = Huntsville, Alabama, Huntsville , LargestCounty = Baldwin County, Al ...

, ''L. aurea'' to

Oklahoma Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a U.S. state, state in the South Central United States, South Central region of the United States, bordered by Texas on the south and west, Kansas on the nor ...

, ''L. stylosa'' to

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

, and ''L. texana'' to

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

Breeding systems

The mating systems found in genus ''Leavenworthia'' have been studied extensively because they are variable and have changed several times in the evolutionary history of the group. Some species are self-compatible, while others are

self-incompatible Self-incompatibility (SI) is a general name for several genetic mechanisms that prevent self-fertilization in sexually reproducing organisms, and thus encourage outcrossing and allogamy. It is contrasted with separation of sexes among individuals ...

. ''L. exigua'', ''L. torulosa'', and ''L. uniflora'' are self-compatible, able to produce seed from

ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...

s fertilized by their own

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...

. In ''L. alabamica'' and ''L. crassa'', separate populations of self-compatible and self-incompatible individuals have been observed. At at least three points in the history of ''Leavenworthia'' there have been transitions between mating systems, in which self-incompatible plants

evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation t ...

self-compatibility, developing the ability to fertilize their own ovules. This process has inspired studies of the

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...

of the genus, which may help explain how such changes occurred. Self-incompatibility is the ancestral state of the genus, and it has been lost several times.Busch, J. W. (2005)
The evolution of self-compatibility in geographically peripheral populations of ''Leavenworthia alabamica'' (Brassicaceae).
''American Journal of Botany'' 92(9), 1503-12. The transition from self-incompatibility to self-compatibility is described as the loss of a barrier, rather than the gain of a new function; in ''L. alabamica'', for example, a

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mi ...

in a pollen

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

may have led to the production of compatible pollen.Chantha, S. C., et al. (2013)
Secondary evolution of a self-incompatibility locus in the Brassicaceae genus ''Leavenworthia''.
''PLoS Biology'' 11(5), e1001560. Self-compatible plants are also shaped differently, with smaller flowers in which the pollen-bearing anthers are positioned closer to the stigma.

Diversity

Taxa include:GRIN Species Records of ''Leavenworthia''.
USDA Germplasm Resources Information Network (GRIN). *''

Leavenworthia alabamica ''Leavenworthia alabamica'' is a species of flowering plant in the family Brassicaceae. It is commonly known as Alabama gladecress. It is endemic to Alabama. Description ''Leavenworthia ''Leavenworthia'' is a genus of flowering plants in th ...

'' – Alabama gladecress **''Leavenworthia alabamica'' var. ''alabamica'' **''Leavenworthia alabamica'' var. ''brachystyla'' *''

Leavenworthia aurea ''Leavenworthia'' is a genus of flowering plants in the family Brassicaceae. It includes about eight species native to the southern and southeastern United States.Leavenworthia crassa ''Leavenworthia crassa'' is a species of flowering plant in the mustard family, Brassicaceae, known commonly as the fleshy-fruit gladecress. It is endemic to Alabama in the United States, where it occurs in only two counties. It is "likely one of ...

'' – fleshyfruit gladecress **''Leavenworthia crassa'' var. ''crassa'' **''Leavenworthia crassa'' var. ''elongata'' *''

Leavenworthia exigua ''Leavenworthia exigua'', also known as the Tennessee gladecress, is a member of the mustard family. Tennessee gladecress is an annual plant that is native to southern United States. It is a fruit-bearing plant, with squarish leaves that fall o ...

'' – Tennessee gladecress **''Leavenworthia exigua'' var. ''exigua'' **''Leavenworthia exigua'' var. ''laciniata'' – Kentucky gladecress **''Leavenworthia exigua'' var. ''lutea'' *''

Leavenworthia stylosa ''Leavenworthia stylosa'' is a species of flowering plant in the family Brassicaceae known by the common names cedar gladecress or long-styled gladecress. It is found only in the Central Basin of Tennessee, where it grows in cedar glades, ditche ...

'' – cedar gladecress *''

Leavenworthia texana ''Leavenworthia'' is a genus of flowering plants in the family Brassicaceae. It includes about eight species native to the southern and southeastern United States.Leavenworthia torulosa ''Leavenworthia torulosa'', the necklace gladecress, is a species of plant in the mustard family. It is native to the eastern United States where it is only found near limestone cedar glades of Alabama, Georgia, Kentucky, and Tennessee. It is con ...

'' – necklace gladecress *'' Leavenworthia uniflora'' – Michaux's gladecress

Description

Ecology

Breeding systems

Diversity

References

Further reading