Editing Brassicaceae (section)

== Description ==
[[File:Ricotia Lunaria.jpg|right|thumb|''[[Ricotia lunaria]]'']]
Species belonging to the Brassicaceae are mostly [[Annual plant|annual]], [[Biennial plant|biennial]], or [[Perennial plant|perennial]] [[herbaceous plant]]s, some are [[dwarf shrub]]s or [[shrub]]s, and very few [[vine]]s. Although generally terrestrial, a few species such as [[water awlwort]] live submerged in fresh water. They may have a [[taproot]] or a sometimes woody [[caudex]] that may have few or many branches, some have thin or tuberous [[rhizome]]s, or rarely develop [[Stolon|runners]]. Few species have multi-cellular glands. [[Trichome|Hairs]] consist of one cell and occur in many forms: from simple to forked, star-, tree- or T-shaped, rarely taking the form of a shield or scale. They are never topped by a gland. The [[Plant stem|stem]]s may be upright, rise up towards the tip, or lie flat, are mostly herbaceous but sometimes woody. Stems carry leaves or the stems may be leafless (in ''[[Caulanthus]]''), and some species lack stems altogether. The leaves do not have [[stipule]]s, but there may be a pair of glands at base of [[Petiole (botany)|leaf stalks]] and [[Pedicel (botany)|flower stalks]]. The leaf may be seated or have a leafstalk. The [[Leaf#Morphology (large-scale features)|leaf blade]] is usually simple, entire or [[Leaf#Divisions of the blade|dissected]], rarely [[Leaf#Divisions of the blade|trifoliolate]] or [[Leaf#Divisions of the blade|pinnately compound]]. A leaf rosette at the base may be present or absent. The leaves along the stem are almost always [[Leaf#Arrangement on the stem|alternately arranged]], rarely apparently opposite.<ref name=Neotropikey>{{cite web|website= Neotropikey—Interactive key and information resources for flowering plants of the Neotropics|title= Neotropical Brassicaceae|author= Al-Shehbaz, I.A.|year= 2012|url=  http://www.kew.org/science/tropamerica/neotropikey/families/Brassicaceae.htm|access-date= 2017-07-12}}</ref> The stomata are of the [[Stoma#anisocytic|anisocytic]] type.<ref>{{cite book|first1= C.R.|last1= Metcalfe|first2= L.|last2= Chalk|year= 1950|title= Anatomy of Dicotyledons|volume= 1: Leaves, Stem, and Wood in relation to Taxonomy, with notes on economic Uses|pages= 79–87|url= https://archive.org/stream/anatomyofthedico033552mbp#page/n157/mode/2up|publisher= Oxford At The Clarendon Press.}}</ref> The [[genome size]] of Brassicaceae compared to that of other Angiosperm families is very small to small (less than 3.425 million base pairs per cell), varying from 150 Mbp in ''[[Arabidopsis thaliana]]'' and ''[[Sphaerocardamum]]'' spp., to 2375 Mbp ''[[Bunias orientalis]]''. The number of [[homologous chromosomes|homologous chromosome sets]] varies from four (n=4) in some ''[[Physaria]]'' and ''[[Stenopetalum]]'' species, five (n=5) in other ''Physaria'' and ''Stenopetalum'' species, ''Arabidopsis thaliana'' and a ''[[Mathiola]]'' species, to seventeen (n=17). About 35% of the species in which chromosomes have been counted have eight sets (n=8). Due to [[polyploidy]], some species may have up to 256 individual chromosomes, with some very high counts in the North American species of ''Cardamine'', such as ''[[Cardamine diphylla|C. diphylla]]''. [[Hybrid (biology)|Hybridisation]] is not unusual in Brassicaceae, especially in ''[[Arabis]]'', ''[[Rorippa]]'', ''[[Cardamine]]'' and ''[[Boechera]]''. Hybridisation between species originating in Africa and California, and subsequent [[Speciation#Speciation via polyploidization|polyploidisation]] is surmised for ''[[Lepidium]]'' species native to Australia and New Zealand.<ref name=SB />

=== Inflorescence and flower ===
[[Image:Floral diagram Erysimum Bowles Mauve 2.jpg|thumb|left|Typical [[floral diagram]] of a Brassicaceae (''Erysimum'' "Bowles' Mauve")]]Flowers may be arranged in [[raceme]]s, [[panicle]]s, or [[corymb]]s, with pedicels sometimes in the axil of a bract, and few species have flowers that sit individually on flower stems that spring from the axils of rosette leaves. The orientation of the pedicels when fruits are ripe varies dependent on the species. The flowers are [[Plant reproductive morphology#Terminology|bisexual]], [[Floral symmetry#Actinomorphic|star symmetrical]] (zygomorphic in ''[[Iberis]]'' and ''[[Teesdalia]]'') and the [[Ovary (botany)#Superior ovary|ovary positioned above the other floral parts]]. Each flower has four free or seldom merged [[sepal]]s, the lateral two sometimes with a shallow spur, which are mostly shed after flowering, rarely persistent, may be reflexed, spreading, ascending, or erect, together forming a tube-, bell- or urn-shaped calyx. Each flower has four [[petal]]s, set alternating with the sepals, although in some species these are rudimentary or absent. They may be differentiated into a [[Petal#Shape and size|blade]] and a [[Petal#Shape and size|claw]] or not, and consistently lack basal appendages. The blade is entire or has an indent at the tip, and may sometimes be much smaller than the claws. The mostly six [[stamen]]s are set in two whorls: usually the two lateral, outer ones are shorter than the four inner stamens, but very rarely the stamens can all have the same length, and very rarely species have different numbers of stamens such as sixteen to twenty four in ''[[Megacarpaea]]'', four in ''[[Cardamine hirsuta]]'', and two in ''[[Coronopus]]''. The filaments are slender and not fused, while the anthers consist of two pollen producing cavities, and open with longitudinal slits. The pollen grains are [[tricolpate]]. The [[Receptacle (botany)|receptacle]] carries a variable number of [[nectar]]ies, but these are always present opposite the base of the lateral stamens.<ref name=Neotropikey /><ref name=BioDis>{{cite web|website= biologydiscussion|title= Brassicaceae: Characters, Distribution and Types (With Diagram)|url= http://www.biologydiscussion.com/angiosperm/dicotyledons/brassicaceae-characters-distribution-and-types-with-diagram/47923|access-date= 12 July 2017|date= 2016-08-30}}</ref>

=== Ovary, fruit and seed ===
There is one [[Gynoecium#Gynoecium position|superior]] [[Gynoecium#Pistils|pistil]] that consists of two [[carpel]]s that may either sit directly above the base of the stamens or on a [[Gynophore|stalk]]. It initially consists of only one cavity but during its further development a thin wall grows that divides the cavity, both placentas and separates the two valves (a so-called false septum). Rarely, there is only one cavity without a septum. The 2–600 [[ovule]]s are usually along the side margin of the carpels, or rarely at the top. Fruits are capsules that open with two valves, usually towards the top. These are called [[silique]] if at least three times longer than wide, or [[silicle]] if the length is less than three times the width. The fruit is very variable in its other traits. There may be one persistent [[Stigma (botany)#Style|style]] that connects the ovary to the globular or conical [[Stigma (botany)|stigma]], which is undivided or has two spreading or connivent lobes. The variously shaped seeds are usually yellow or brown in color, and arranged in one or two rows in each cavity. The [[Cotyledon|seed leaves]] are entire or have a notch at the tip. The seed does not contain [[endosperm]].<ref name=Neotropikey />

=== Differences with similar families ===
Brassicaceae have a bisymmetrical corolla (left is mirrored by right, stem-side by out-side, but each quarter is not symmetrical), a septum dividing the fruit, lack [[stipule]]s and have simple (although sometimes deeply incised) leaves. The [[sister group|sister family]] [[Cleomaceae]] has [[Floral symmetry#Zygomorphic|bilateral symmetrical]] corollas (left is mirrored by right, but stem-side is different from out-side), stipules and mostly palmately divided leaves, and mostly no septum.<ref name=Neotropikey /> Capparaceae generally have a [[gynophore]], sometimes an [[androgynophore]], and a variable number of stamens.<ref name=BioDis />

=== Phytochemistry ===
Almost all Brassicaceae have [[C3 carbon fixation]]. The only exceptions are a few ''[[Moricandia]]'' species, which have a hybrid system between C3 and [[C4 carbon fixation]], C4 fixation being more efficient in drought, high temperature and low nitrate availability.<ref>{{cite book|title= The Plant Family Brassicaceae: Contribution Towards Phytoremediation|series= Environmental Pollution|editor= Naser A. Anjum |editor2=Iqbal Ahmad |editor3=M. Eduarda Pereira |editor4=Armando C. Duarte |editor5=Shahid Umar |editor6=Nafees A. Khan|publisher= Springer Science & Business Media|year= 2012|url= https://books.google.com/books?id=O8VTRtgkrXQC&q=brassicaceae&pg=PA25|isbn= 9789400739123}}</ref> Brassicaceae contain different cocktails of dozens of [[glucosinolate]]s. They also contain enzymes called [[myrosinase]]s, that convert the glucosinolates into [[isothiocyanate]]s, [[thiocyanate]]s and [[nitrile]]s, which are toxic to many organisms, and so help guard against herbivory.<ref name=HAW />