genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of
flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s in the cabbage family,
Brassicaceae
Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some are shrubs. The leav ...
. It includes more than 150
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
, both popular garden plants and many wild forms. The genus ''Cheiranthus'' is sometimes included here in whole or in part. ''Erysimum'' has since the early 21st century been ascribed to a monogeneric cruciferous
tribe
The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to confli ...
, Erysimeae, characterised by
sessile
Sessility, or sessile, may refer to:
* Sessility (motility), organisms which are not able to move about
* Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant
* Sessility (medicine), tumors and polyps that ...
trichomes
Trichomes (); ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...
, yellow to orange flowers and multiseeded
siliques
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 i ...
.
Morphology
Wallflowers are
annual
Annual may refer to:
*Annual publication, periodical publications appearing regularly once per year
** Yearbook
** Literary annual
*Annual plant
*Annual report
*Annual giving
*Annual, Morocco, a settlement in northeastern Morocco
*Annuals (band), ...
perennial
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wid ...
s or sub-shrubs. The perennial species are short-lived and in cultivation treated as biennials. Most species have stems erect, somewhat winged, canescent with an
indumentum
In biology, an indumentum (Latin, literally: "garment") is a covering of trichomes (fine "hairs") on a plant Davis, Peter Hadland and Heywood, Vernon Hilton (1963) ''Principles of angiosperm taxonomy'' Van Nostrandpage, Princeton, New Jersey, pa ...
of bifid hairs, usually 25 ± 53 cm × 2–3 mm in size, and t-shaped
trichome
Trichomes (); ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a p ...
s. The leaves are narrow and sessile. The lower leaves are linear to oblanceolate pinnatifid with backwardly directed lobes, acute, 50–80 mm × 0.5–3 mm. Stem leaves are linear, entire, all canescent with 2-fid hairs; 21–43 mm × 1.5–2 mm.
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...
s are produced in racemes, with bright yellow to red or pink bilateral and hermaphrodite,
hypogynous
In the flowering plants, an ovary is a part of the female reproductive organ of the flower or gynoecium. Specifically, it is the part of the pistil which holds the ovule(s) and is located above or below or at the point of connection with the bas ...
and
ebracteate
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...
flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s. Flowering occurs during spring and summer. One species, ''
Erysimum semperflorens
''Erysimum'', or wallflower, is a genus of flowering plants in the cabbage family, Brassicaceae. It includes more than 150 species, both popular garden plants and many wild forms. The genus ''Cheiranthus'' is sometimes included here in whole o ...
'', native to Morocco and Algeria, has white flowers. The floral pedicel ranges from 4 to 7 mm. Four free
sepal
A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coine ...
s somewhat saccate, light green, 5–7 mm × 1.5–2 mm.
Etymology
The
genus name
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
''Erysimum'' is derived from the Greek word 'Eryo' meaning to drag.
Distribution
Wallflowers are native to southwest Asia, the Mediterranean, Europe, Africa (Cabo Verde), Micronesia, and North America through Costa Rica. Many wallflowers are
endemic
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 ...
Teide
Teide, or Mount Teide, ( es, El Teide, Pico del Teide, , "Peak of Teide") is a volcano on Tenerife in the Canary Islands, Spain. Its summit (at ) is the highest point in Spain and the highest point above sea level in the List of islands in th ...
volcano on Tenerife)
*'' E. teretifolium'' (endangered – inland sandhills of Santa Cruz County, California)
Cultivation
Most wallflower garden
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...
s (e.g. ''Erysimum'' 'Chelsea Jacket') are derived from '' E. cheiri'' (often placed in ''Cheiranthus''), from southern Europe. They are often attacked by fungal and bacterial disease, so they are best grown as biennials and discarded after flowering. They are also susceptible to
clubroot
Clubroot is a common disease of cabbages, broccoli, cauliflower, Brussels sprouts, radishes, turnips, stocks, wallflowers and other plants of the family Brassicaceae (Cruciferae). It is caused by ''Plasmodiophora brassicae'', which was once cons ...
, a disease of
Brassicaceae
Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some are shrubs. The leav ...
. Growth is best in dry soils with very good drainage, and they are often grown successfully in loose wall mortar, hence the vernacular name. There is a wide range of flower color in the warm spectrum, including white, yellow, orange, red, pink, maroon, purple and brown. The flowers, appearing in spring, usually have a strong fragrance. Wallflowers are often associated in spring
bedding
Bedding, also known as bedclothes or bed linen, is the materials laid above the mattress of a bed for hygiene, warmth, protection of the mattress, and decorative effect. Bedding is the removable and washable portion of a human sleeping environm ...
schemes with
tulip
Tulips (''Tulipa'') are a genus of spring-blooming perennial herbaceous bulbiferous geophytes (having bulbs as storage organs). The flowers are usually large, showy and brightly coloured, generally red, pink, yellow, or white (usually in warm ...
s and
forget-me-not
''Myosotis'' ( ) is a genus of flowering plants in the family Boraginaceae. The name comes from the Ancient Greek "mouse's ear", which the foliage is thought to resemble. In the northern hemisphere they are colloquially known as forget-me-no ...
s.
The cultivar 'Bowles's Mauve' has gained the
Royal Horticultural Society
The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity.
The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr (Nor ...
's Award of Garden Merit. It can become a bushy evergreen perennial in milder locations. It is strongly scented and attractive to bees.
Ecology
''Erysimum'' is found in a range of habitats across the northern hemisphere, and has developed diverse morphology and growth habits (herbaceous annual or perennial, and woody perennial). ''Different Erysimum'' species are used as food plants by the
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
...
moth
Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
s) species including the garden carpet (''Xanthorhoe fluctuata''). In addition, some species of weevils, like '' Ceutorhynchus chlorophanus'', live inside the fruits feeding on the developing seeds. Many species of beetles, bugs and grasshoppers eat the leaves and stalks. Some mammalian herbivores, for example mule deer (''
Odocoileus hemionus
The mule deer (''Odocoileus hemionus'') is a deer indigenous to western North America; it is named for its ears, which are large like those of the mule. Two subspecies of mule deer are grouped into the black-tailed deer.
Unlike the related w ...
'') in North America, argali ('' Ovis ammon'') in Mongolia, red deer (''
Cervus elaphus
The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of wes ...
'') in Central Europe, or Spanish ibex ('' Capra pyrenaica'') in the Iberian Peninsula, feed on wallflower flowering and fruiting stalks. '' Erysimum crepidifolium'' (pale wallflower) is toxic to some generalist vertebrate herbivores.Bleicher Schöterich (''Erysimum crepidifolium''). In: giftpflanzen.com. /ref>
Most wallflowers are pollinator-generalists, their flowers being visited by many different species of bees, bee flies, hoverflies, butterflies, beetles, and ants. However, there are some specialist species. For example, ''
Erysimum scoparium
''Erysimum scoparium'' is a species of flowering plant in the family Brassicaceae, native to the Canary Islands. It is a shrubby species of wallflower with purplish flowers found at high altitudes.
Description
''Erysimum scoparium'' is a small s ...
'' is pollinated almost exclusively by ''
Anthophora
The bee genus ''Anthophora'' is one of the largest in the family Apidae, with over 450 species worldwide in 14 different subgenera. They are most abundant and diverse in the Holarctic and African biogeographic regions. All species are solitary, th ...
alluadii''.
Defensive compounds
Like most
Brassicaceae
Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some are shrubs. The leav ...
, species in the genus ''Erysimum'' produce
glucosinolates
Glucosinolates are natural components of many pungent plants such as mustard, cabbage, and horseradish. The pungency of those plants is due to mustard oils produced from glucosinolates when the plant material is chewed, cut, or otherwise damaged. T ...
as defensive compounds. However, unlike almost all other genera in the Brassicaceae, ''Erysimum'' also accumulates
cardiac glycosides
Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses are as treatments for co ...
, another class of
phytochemicals
Phytochemicals are chemical compounds produced by plants, generally to help them resist fungi, bacteria and plant virus infections, and also consumption by insects and other animals. The name comes . Some phytochemicals have been used as poison ...
with an ecological importance in insect defense. Cardiac glycosides specifically function to prevent insect
herbivory
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
and/or oviposition by blocking ion channel function in muscle cells. These chemicals are toxic enough to deter generalist, and even some specialist insect herbivores.
Cardiac glycoside
Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses are as treatments for c ...
production is widespread in ''Erysimum'', with at least 48 species in the genus containing these compounds. Accumulation of cardiac glycosides in '' Erysimum crepidifolium'', but not other tested species, is induced by treatment with jasmonic acid and
methyl jasmonate
Methyl jasmonate (abbreviated MeJA) is a volatile organic compound used in plant defense and many diverse developmental pathways such as seed germination, root growth, flowering, fruit ripening, and senescence. Methyl jasmonate is derived from ...
, endogenous elicitors of chemical defenses in many plant species. Molecular
phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
analysis indicates that ''Erysimum'' diversification from other
Brassicaceae
Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some are shrubs. The leav ...
species that do not produce cardiac glycosides began in the
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 suggesting relatively recent evolution of cardiac glycosides as a defensive trait in this genus.
Escape from herbivory
The evolution of novel chemical defenses in plants, such as
cardenolide
A cardenolide is a type of steroid. Many plants contain derivatives, collectively known as cardenolides, including many in the form of cardenolide glycosides (cardenolides that contain structural groups derived from sugars). Cardenolide glycoside ...
s in the genus ''Erysimum'', is predicted to allow escape from herbivory by specialist herbivores and expansion into new ecological niches. The crucifer-feeding specialist '' Pieries rapae'' (white cabbage butterfly) is deterred from feeding and oviposition by cardenolides in '' Erysimum cheiranthoides.'' Similarly, ''Anthocharis cardamines'' (orange tip butterfly), which oviposits on almost all crucifer species, avoids '' E. cheiranthoides.'' ''Erysimum asperum'' (western wallflower) is resistant to feeding and oviposition of ''Pieris napi macdunnoughii'' (synonym '' Pieris marginalis'', margined white butterfly). Two crucifer-feeding beetles, ''Phaedon'' sp. and ''
Phyllotreta
''Phyllotreta'' is a genus of flea beetles in the family Chrysomelidae. There are at least 300 described species worldwide.https://www.zin.ru/animalia/coleoptera/addpages/Nadein/Phyllotr.htm
Agricultural pests
Many species have been recorded ...
'' sp., were deterred from feeding by
cardenolide
A cardenolide is a type of steroid. Many plants contain derivatives, collectively known as cardenolides, including many in the form of cardenolide glycosides (cardenolides that contain structural groups derived from sugars). Cardenolide glycoside ...
s that were applied to their preferred food plants. Consistent with the hypothesis of enhanced speciation after escape from herbivory, phylogenetic studies involving 128 ''Erysimum'' species indicate diversification in Eurasia between 0.5 and 2 million years ago, and in North America between 0.7 and 1.65 million years ago.) This evolutionarily rapid expansion of the ''Erysimum'' genus has resulted in several hundred known species distributed throughout the northern hemisphere.
Ethnobotanical uses of ''Erysimum''
''Erysimum'' species have a long history of use in traditional medicine. In
Naturalis Historia
The ''Natural History'' ( la, Naturalis historia) is a work by Pliny the Elder. The largest single work to have survived from the Roman Empire to the modern day, the ''Natural History'' compiles information gleaned from other ancient authors. ...
by
Pliny the Elder
Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic ' ...
(~77), ''Erysimum'' is classified as a medicinal rather than a food plant. ''
Erysimum cheiri
''Erysimum cheiri'', syn. ''Cheiranthus cheiri'', the wallflower, is a species of flowering plant in the family Brassicaceae (Cruciferae), native to Greece, but widespread as an introduced species elsewhere. It is also treated as a hybrid under t ...
'' is described as a medicinal herb in
De Materia Medica
(Latin name for the Greek work , , both meaning "On Medical Material") is a pharmacopoeia of medicinal plants and the medicines that can be obtained from them. The five-volume work was written between 50 and 70 CE by Pedanius Dioscorides, ...
by
Pedanius Dioscorides
Pedanius Dioscorides ( grc-gre, Πεδάνιος Διοσκουρίδης, ; 40–90 AD), “the father of pharmacognosy”, was a Greek physician, pharmacologist, botanist, and author of '' De materia medica'' (, On Medical Material) —a 5-vo ...
(~70), which was the predominant European medical
pharmacopeia
A pharmacopoeia, pharmacopeia, or pharmacopoea (from the obsolete typography ''pharmacopœia'', meaning "drug-making"), in its modern technical sense, is a book containing directions for the identification of compound medicines, and published by ...
for more than 1,500 years. Other
medieval
In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
descriptions of medicinal herbs and their uses, including the Dispensatorium des Cordus by
Valerius Cordus
Valerius Cordus (18 February 1515 – 25 September 1544) was a German physician, botanist and pharmacologist who authored the first pharmacopoeia North of the Alps and one of the most celebrated herbals in history. He is also widely credited wit ...
(1542), Bocks Kräuterbuch by Hieronymus Bock (1577), and Tabernaemontanus’ Neuw Kreuterbuch by Jacobus Theodorus Tabernaemontanus (1588), also discuss applications of '' E. cheiri''. In traditional Chinese medicine, '' Erysimum cheiranthoides'' has been used to treat heart disease and other ailments. Although medical uses of ''Erysimum'' became uncommon in
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...
after the
Middle Ages
In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
, ''Erysimum diffusum,'' as well as purified erysimin and erysimoside, have been applied more recently as Ukrainian ethnobotanical treatments.
Erysimum caboverdeanum
''Erysimum caboverdeanum'' is a species of flowering plants of the family Brassicaceae. The species is endemic to Cape Verde.Oromí, Martín, Zurita & Cabrera, 2005 : Lista preliminar de especies silvestres de Cabo Verde: Hongos, Plantas y Animal ...
Erysimum scoparium
''Erysimum scoparium'' is a species of flowering plant in the family Brassicaceae, native to the Canary Islands. It is a shrubby species of wallflower with purplish flowers found at high altitudes.
Description
''Erysimum scoparium'' is a small s ...
Erysimum teretifolium
''Erysimum teretifolium'' is a species of ''Erysimum'' known by the common names Santa Cruz wallflower and Ben Lomond wallflower. It is a very rare plant endemic to Santa Cruz County, California, where it grows on inland sand spits, chaparral, an ...