Brassicaceae

Brassicaceae
Winter cress, Barbarea vulgaris
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Brassicales
Family: Brassicaceae
Burnett[1]
Genera

See text.

Brassicaceae is the name of a medium-sized and economically important family of flowering plants (angiosperms), informally known as the mustards, mustard flowers, the crucifers, or the cabbage family.

The name Brassicaceae is derived from the included genus Brassica. Cruciferae, an older name, meaning "cross-bearing", describes the four petals of mustard flowers, which resemble a cross; it is one of eight plant family names without the suffix '-aceae' that are authorized alternative names (according to ICBN Art. 18.5 and 18.6 Vienna Code); thus both Cruciferae and Brassicaceae are used.

The family contains 372 genera and 4060 accepted species. The largest genera are Draba (440 species), Erysimum (261 species), Lepidium (234 species), Cardamine (233 species), and Alyssum (207 species).

The family contains well-known species such as Brassica oleracea (broccoli, cabbage, cauliflower, etc.), Brassica rapa (turnip, Chinese cabbage, etc.), Brassica napus (rapeseed, etc.), Raphanus sativus (common radish), Armoracia rusticana (horseradish), Matthiola (stock), Arabidopsis thaliana (thale cress) (model organism), and many others.

Pieris rapae and other butterflies of the Pieridae family are some of the most well-known pests of the commercial cropping of Brassicaceae species.

Taxonomy

The family is included in the Brassicales according to the APG system. Older systems (e.g., Arthur Cronquist's) placed them into the Capparales, a now-defunct order that had a similar definition.

This family comprises about 365 genera and 3200 species all over the world; 94 species of 38 genera are found in Nepal. The plants are mostly herbs. A close relationship has long been acknowledged between the Brassicaceae and the caper family, Capparaceae, in part because members of both groups produce glucosinolate (mustard oil) compounds. The Capparaceae as traditionally circumscribed were paraphyletic with respect to Brassicaceae, with Cleome and several related genera being more closely related to the Brassicaceae than to other Capparaceae.[2] The APG II system, therefore, has merged the two families under the name Brassicaceae. Other classifications have continued to recognize the Capparaceae, but with a more restricted circumscription, either including Cleome and its relatives in the Brassicaceae or recognizing them in the segregate family Cleomaceae. The APG III system has recently adopted this last solution, but this may change as a consensus arises on this point. This article deals with Brassicaceae sensu stricto, i.e. treating the Cleomaceae and Capparaceae as segregated families.

 Brassicaceae s.l. 

Capparaceae

Cleomaceae

Brassicaceae s.s.




Description

Aubrieta deltoidea (commonly known as purple rock cress) is a perennial wild flower used in gardening for its ornamental large inflorescence.

The family consists mostly of herbaceous plants with annual, biennial, or perennial lifespans. However, around the Mediterranean, they include also a dozen woody shrubs 1-3 m tall, e.g. in northern Africa (Zilla spinosa and Ptilotrichum spinosum), in the Dalmatian islands (Dendralyssum and Cramboxylon), and chiefly in Canarias with some woody cruciferous genera: Dendrosinapis, Descurainia, Parolinia, Stanleya, etc..

The leaves are alternate (rarely opposite), sometimes organized in basal rosettes; in rare shrubby crucifers of Mediterranean their leaves are mostly in terminal rosettes, and may be coriaceous and evergreen. They are very often pinnately incised and do not have stipules.

The structure of the flowers is extremely uniform throughout the family. They have four free saccate sepals and four clawed free petals, staggered. They can be disymmetric or slightly zygomorphic, with a typical cross-like arrangement (hence the name Cruciferae). They have six stamens, four of which are longer (as long as the petals, so relatively short in fact) and are arranged in a cross like the petals and the other two are shorter (tetradynamous flower). The pistil is made up of two fused carpels and the style is very short, with two lobes. The ovary is superior. The flowers form ebracteate racemose inflorescences, often apically corymb-like.

Pollination occurs by entomogamy; nectar is produced at the base of the stamens and stored on the sepals.

Siliquae of Cardamine impatiens

The fruit is a peculiar kind of capsule named siliqua (plural siliquae). It opens by two valves, which are the modified carpels, leaving the seeds attached to a framework made up of the placenta and tissue from the junction between the valves (replum). Often, an indehiscent beak occurs at the top of the style and one or more seeds may be borne there. Where a siliqua is less than three times as long as it is broad, it is usually termed a silicula. The siliqua may break apart at constrictions occurring between the segments of the seeds, thus forming a sort of loment (e.g., Raphanus), it may eject the seeds explosively (e.g., Cardamine) or may be evolved in a sort of samara (e.g., Isatis). The fruit is often the most important diagnostic character for plants in this family. Most members share a suite of glucosinolate compounds that have a typical pungent odour usually associated with cole crops.

Uses

Lunaria annua with ripe seed pods
Smelowskia americana is endemic to the midlatitude mountains of western North America.

The importance of this family for food crops has led to its selective breeding throughout history. Some examples of cruciferous food plants are the cabbage, broccoli, cauliflower, turnip, rapeseed, mustard, radish, horseradish, cress, wasabi, and watercress.

Matthiola (stock), Cheiranthus, Lobularia, and Iberis (candytufts) are appreciated for their flowers. Lunaria (honesty) is cultivated for the decorative value of the translucent replum of the round silicula that remains on the dried stems after dehiscence.

Capsella bursa-pastoris, Lepidium, and many Cardamine species are common weeds.

Isatis tinctoria (woad) was used in the past to produce the colour indigo.

Arabidopsis thaliana is a very important model organism in the study of the flowering plants (Angiospermae).

Genera

See also

References

  1. ↑ Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III" (PDF). Botanical Journal of the Linnean Society 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. Retrieved 2013-07-06.
  2. ↑ Hall, J. C.; Sytsma, K. J.; Iltis, H. H. (2002). "Phylogeny of Capparaceae and Brassicaceae based on chloroplast sequence data". American Journal of Botany 89 (11): 1826–1842. doi:10.3732/ajb.89.11.1826. PMID 21665611.

Further reading

External links

Wikimedia Commons has media related to Brassicaceae.
Wikispecies has information related to: Brassicaceae
This article is issued from Wikipedia - version of the Sunday, March 13, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.