Boechera
Encyclopedia
Boechera is a genus
of the family Brassicaceae
. It was named after the Danish
botanist Tyge W. Böcher
(1909–1983), who was known for his research in alpine plants, including the mustards Draba
and Boechera holboellii. According to recent molecular based studies Boechera is closely related to the genus Arabidopsis which also includes the widely known model plant Arabidopsis thaliana.
Until recently, members of this genus were included in the genus Arabis
, but have been separated from that genus based on recent genetic
and cytological data. Unlike the genus Arabis (x=8) Boechera has a base chromosome number of x=7. Many taxa are triploid. Boechera is a primarily North American genus, most diverse in the western United States
but its distribution range also includes Greenland and the Russian Far East. The genus is poorly known, and species within are difficult to separate morphologically though some clearly distinct species are known.
Most members of the genus are perennial plant
s with pubescent leaves with stellate trichomes, narrow curving fruits, and small white to purple flower
s in elongated raceme
s. Relationships within the genus are unclear, and some eastern North American species, including Boechera laevigata, may belong to a clade
distinct from the rest of the genus.
A very interesting feature of many species of the genus is asexual reproduction
, a process known as apomixis
. Microsatellite data has revealed that some of the apomictic lineages are hybrids between two or more sexual
parents.
Selected species
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of the family Brassicaceae
Brassicaceae
Brassicaceae, a medium sized and economically important family of flowering plants , are informally known as the mustards, mustard flowers, the crucifers or the cabbage family....
. It was named after the Danish
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
botanist Tyge W. Böcher
Tyge W. Böcher
Tyge Wittrock Böcher was a Danish botanist, evolutionary biologist, plant ecologist and phytogeographer.He was born in Copenhagen to physician Einar Böcher and wife Cathinca née Andersen. Steen B. Böcher, professor of geography, was his brother.Tyge Böcher was professor of botany at the University...
(1909–1983), who was known for his research in alpine plants, including the mustards Draba
Draba
Draba is a large genus of cruciferous plants, commonly known as whitlow-grasses. There are over 400 species:*Draba abajoensis Windham & Al-Shehbaz*Draba × abiskoensis O.E.Schulz*Draba × abiskojokkensis O.E.Schulz...
and Boechera holboellii. According to recent molecular based studies Boechera is closely related to the genus Arabidopsis which also includes the widely known model plant Arabidopsis thaliana.
Until recently, members of this genus were included in the genus Arabis
Arabis
Arabis , or rockcress, is a genus of flowering plants, within the family Brassicaceae, subfamily Brassicoideae.Though traditionally recognized as a large genus with many Old World and New World members, more recent evaluations of the relationships among these species using genetic data suggest that...
, but have been separated from that genus based on recent genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
and cytological data. Unlike the genus Arabis (x=8) Boechera has a base chromosome number of x=7. Many taxa are triploid. Boechera is a primarily North American genus, most diverse in the western United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
but its distribution range also includes Greenland and the Russian Far East. The genus is poorly known, and species within are difficult to separate morphologically though some clearly distinct species are known.
Most members of the genus are perennial plant
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
s with pubescent leaves with stellate trichomes, narrow curving fruits, and small white to purple flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s in elongated raceme
Raceme
A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
s. Relationships within the genus are unclear, and some eastern North American species, including Boechera laevigata, may belong to a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
distinct from the rest of the genus.
A very interesting feature of many species of the genus is asexual reproduction
Asexual reproduction
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
, a process known as apomixis
Apomixis
In botany, apomixis was defined by Winkler as replacement of the normal sexual reproduction by asexual reproduction, without fertilization. This definition notably does not mention meiosis...
. Microsatellite data has revealed that some of the apomictic lineages are hybrids between two or more sexual
Plant sexuality
Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....
parents.
Selected species
- Boechera breweriBoechera breweriBoechera breweri is a species of flowering plant in the mustard family known by the common name Brewer's rockcress. It is native to southern Oregon and northern California, where it grows in rocky areas in mountains and valleys. This is a perennial herb growing from a woody, branching caudex. It...
(Brewer's Rockcress) - Boechera canadensis (Sicklepod)
- Boechera cobrensis (Sagebrush Rockcress)
- Boechera constanceiBoechera constanceiBoechera constancei is a species of flowering plant in the mustard family known by the common name Constance's rockcress. It is endemic to California, where it is known only from the northern Sierra Nevada of Plumas and Sierra Counties. It is a member of the serpentine soils flora. This is a...
(Constance's Rockcress) - Boechera crandalliiBoechera crandalliiBoechera crandallii is found in Colorado where it is found on limestone chip-rock and stony areas, often among sagebrush. Flowering time is from may to June....
(Crandall's Rockcress) - Boechera disparBoechera disparBoechera dispar is a species of flowering plant in the mustard family known by the common name pinyon rockcress. It is native to eastern California and western Nevada, where it grows in rocky areas in desert and mountain habitat. This is a perennial herb growing from a branching caudex. It produces...
(Pinyon Rockcress) - Boechera falcatoriaBoechera falcatoriaBoechera falcatoria is a rare species of flowering plant in the mustard family known by the common name Grouse Creek rockcress. It is endemic to Utah in the United States, where it is known only from Box Elder County...
(Grouse Creek Rockcress) - Boechera fecunda (Sapphire Rockcress)
- Boechera gracilenta (Selby's Rockcress)
- Boechera gunnisonianaBoechera gunnisonianaBoechera gunnisoniana, , is a perennial herb belonging to the Brassicaceae family . It grows on windswept ridges as well as on stoney hillsides in west-central Colorado. The plant has many slender, erect stems which may reach a height of 15 cm...
(Gunnison's Rockcress) - Boechera holboelliiBoechera holboelliiBoechera holboellii or Holbøll's Rockcress is found in Greenland. Its cytology has been much studied by the Danish botanist Tyge W. Böcher...
(Holboell's Rockcress) - Boechera laevigata (Smooth Rockcress)
- Boechera lignifera (Desert Rockcress)
- Boechera ophiraBoechera ophiraBoechera ophira is a rare species of flowering plant in the mustard family known by the common name Ophir Pass rockcress, or Ophir rockcress. It is endemic to Nevada in the United States, where it is known from Nye and Lander Counties...
(Ophir Rockcress) - Boechera oxylobula (Glenwood Springs Rockcress)
- Boechera pallidifolia (Gunnison County Rockcress)
- Boechera perennansBoechera perennansBoechera perennans is a species of rockcress known as perennial rockcress. It is native to the southwestern United States and northern Mexico. This rockcress forms several erect stems reaching past half a meter in height at maximum...
(Perennial Rockcress) - Boechera pulchra (Beautiful Rockcress)
- Boechera sparsifloraBoechera sparsifloraBoechera sparsiflora is a species of rockcress known by the common names sicklepod rockcress and elegant rockcress. It is native to western North America from California to Utah to Yukon, where it can be found in a number of habitats. This is a coarsely hairy perennial herb growing one or more...
(Sicklepod Rockcress) - Boechera strictaBoechera strictaBoechera stricta is a species of flowering plant in the mustard family known by the common name Drummond's rockcress. It is native to much of North America, including most of Canada, and the western and northeastern United States. It can be found in many habitat types, including disturbed areas...
(Drummond's Rockcress) - Boechera yorkiiBoechera yorkiiBoechera yorkii is a rare species of flowering plant in the mustard family known by the common name Last Chance rockcress. It is endemic to Inyo County, California, where it is known only from the Last Chance Range in Death Valley National Park...
(Last Chance Rockcress)