''Leavenworthia'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of flowering plants in the family

Brassicaceae Brassicaceae () or (the older but equally valid) Cruciferae () is a medium-sized and economically important Family (biology), family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous pla ...

. 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 In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

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

raceme A raceme () or racemoid is an unbranched, indeterminate growth, 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 ...

. 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 (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s, two short and four long. The fruits are

silique A silique or siliqua (plural ''siliques'' or ''siliquae'') is a type of fruit (seed capsule) having two fused carpels with the length being more than three times the width. When the length is less than three times the width of the dried fruit ...

s 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 is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

substrates, especially

cedar glade A calcareous glade is a type of ecological community that is found in the central Eastern United States. Calcareous glades occur where bedrock such as limestone occurs near or at the surface, and have very shallow and little soil development. Du ...

s.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 only 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 foun ...

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

Alabama Alabama ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South, Deep Southern regions of the United States. It borders Tennessee to the north, Georgia (U.S. state), Georgia to the east, Florida and the Gu ...

, ''L. aurea'' to

Oklahoma Oklahoma ( ; Choctaw language, Choctaw: , ) is a landlocked U.S. state, state in the South Central United States, South Central region of the United States. It borders Texas to the south and west, Kansas to the north, Missouri to the northea ...

, ''L. stylosa'' to

Tennessee Tennessee (, ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Kentucky to the north, Virginia to the northeast, North Carolina t ...

, and ''L. texana'' to

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

Breeding systems

The

mating system A mating system is a way in which a group is structured in relation to sexual behaviour. The precise meaning depends upon the context. With respect to animals, the term describes which males and females mating, mate under which circumstances. Reco ...

s 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 sporangium, megasporangium), ...

s fertilized by their own

pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

. 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 the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

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 Augustinians, Augustinian ...

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, ...

in a pollen

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

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'' – Alabama gladecress **''Leavenworthia alabamica'' var. ''alabamica'' **''Leavenworthia alabamica'' var. ''brachystyla'' *'' Leavenworthia aurea'' – golden gladecress, golden yelloweye *'' Leavenworthia crassa'' – fleshyfruit gladecress **''Leavenworthia crassa'' var. ''crassa'' **''Leavenworthia crassa'' var. ''elongata'' *'' Leavenworthia exigua'' – Tennessee gladecress **''Leavenworthia exigua'' var. ''exigua'' ** ''Leavenworthia exigua'' var. ''laciniata'' – Kentucky gladecress **''Leavenworthia exigua'' var. ''lutea'' *'' Leavenworthia stylosa'' – cedar gladecress *'' Leavenworthia texana'' (syn. ''L. aurea'' var. ''texana'') – Texas golden gladecress *'' Leavenworthia torulosa'' – necklace gladecress *'' Leavenworthia uniflora'' – Michaux's gladecress

Description

Ecology

Breeding systems

Diversity

References

Further reading