Perianth

The perianth (perigonium, perigon or perigone) is the non-reproductive part of the flower, and structure that forms an envelope surrounding the sexual organs, consisting of the calyx (sepals) and the corolla (petals). The term perianth is derived from the Greek περί, peri, meaning around, and άνθος, anthos, meaning flower, while perigonium is derived from gonos, meaning seed, i.e. sexual organs. In the mosses and liverworts (Marchantiophyta), the perianth is the sterile tubelike tissue that surrounds the female reproductive structure (or developing sporophyte).

Mature flower diagram
Diagram showing the parts of a mature flower. In this example the perianth is separated into a calyx (sepals) and corolla (petals)

Flowering plants

In flowering plants, the perianth may be described as being either dichlamydeous/heterochlamydeous in which the calyx and corolla are clearly separate, or homochlamydeous, in which they are indistinguishable (and the sepals and petals are collectively referred to as tepals). When the perianth is in two whorls, it is described as biseriate. While the calyx may be green, known as sepaloid, it may also be brightly coloured, and is then described as petaloid. When the undifferentiated tepals resemble petals, they are also referred to as "petaloid", as in petaloid monocots, orders of monocots with brightly coloured tepals. Since they include Liliales, an alternative name is lilioid monocots. The corolla and petals have a role in attracting pollinators, but this may be augmented by more specialised structures like the corona (see below).

When the corolla consists of separate tepals the term apotepalous is used, or syntepalous if the tepals are fused to one another. The petals may be united to form a tubular corolla (gamopetalous or sympetalous). If either the petals or sepals are entirely absent, the perianth can be described as being monochlamydeous.

Achlamyde

Achlamydeous floral meristem without a corolla or calyx

Haplochlamyde

Monochlamydeous perianth with non-petaloid calyx only

Homochlamyde

Monochlamydeous perianth with corolla only or homochlamydeous perigonium with tepals

Heterochlamyde

Dichlamydeous/heterochlamydeous perianth with separate whorls

Both sepals and petals may have stomata and veins, even if vestigial. In some taxa, for instance some magnolias and water lilies the perianth is arranged in a spiral on nodes, rather than whorls. Flowers with spiral perianths tend to also be those with undifferentiated perianths.

Corona

A Perfect Pair Daffodills (Narcissus) - 8
Flower of Narcissus showing an outer white corolla with a central yellow corona (paraperigonium)
Passiflora incarnata flower and bud
Flower of Passiflora incarnata showing corona of fine appendages between petals and stamens

An additional structure in some plants (e.g. Narcissus, Passiflora (passion flower), some Hippeastrum, Liliaceae) is the corona (paraperigonium, paraperigon, or paracorolla), a ring or set of appendages of adaxial tissue arising from the corolla or the outer edge of the stamens. It is often positioned where the corolla lobes arise from the corolla tube.[1]

The pappus of Asteraceae, considered to be a modified calyx, is also called a corona if it is shaped like a crown.[1]

Ray-floret
Ligulate floret, typical for some members of the family Asteraceae:
A. inferior ovary
B. The calyx is a crown-shaped pappus, called a corona.
C. Anthers are united in a tube around the style, though the filaments are separate.
D. A ligulate petal extends from the tubular corolla.
E. style and stigmas

Bibliography

  • Simpson, Michael G. (2011). Plant Systematics. Academic Press. ISBN 0-08-051404-9. Retrieved 12 February 2014.

References

  1. ^ a b Beentje, H.; Williamson, J. (2010). The Kew Plant Glossary: an Illustrated Dictionary of Plant Terms. Royal Botanic Gardens, Kew: Kew Publishing.

External links

  • The dictionary definition of perianth at Wiktionary
Accessory fruit

An accessory fruit (sometimes called false fruit, spurious fruit, pseudofruit, or pseudocarp) is a fruit in which some of the flesh is derived not from the ovary but from some adjacent tissue exterior to the carpel. Examples of accessory tissue are the receptacle of the strawberry, pineapple, common fig, and mulberry, and the calyx of Gaultheria procumbens or Syzygium jambos. Pomes, such as apples and pears, are also accessory fruits, with much of the fruit flesh derived from a hypanthium. Other example could be the anthocarps specific to the family Nyctaginaceae, where most of the fruit comes from the perianth (floral whorls).

Fruit with fleshy seeds, such as pomegranate or mamoncillo, are not considered to be accessory fruit.

The terms false fruit, spurious fruit, and pseudocarp are older terms for accessory fruit that have been criticized as "inapt", and are not used by some botanists today.

Allium koreanum

Allium koreanum, the Korean rocky chive, is a species of Allium endemic to the Korean Peninsula.It has three to six leaves that are 20–54 cm (7.9–21.3 in) long and 2–7.4 cm (0.79–2.91 in) wide, and a sheath that is 7.6–22.4 cm (3.0–8.8 in) long. The pyxidium is obtuse, triangular and solid. Purple-red flowers bloom in August to November; 74 to 197 flowers form an umbel at the end of a 10–22.2 mm (0.39–0.87 in) long flower stalk. The bract is broadovate, with a caudate end. Perianth lobes are broadoval and 3.8–7.2 cm (1.5–2.8 in) long with a round end and green midrib on the underside.

Anthesis

Anthesis is the period during which a flower is fully open and functional. It may also refer to the onset of that period.The onset of anthesis is spectacular in some species. In Banksia species, for example, anthesis involves the extension of the style far beyond the upper perianth parts. Anthesis of flowers is sequential within an inflorescence, so when the style and perianth are different colours, the result is a striking colour change that gradually sweeps along the inflorescence.Flowers with diurnal anthesis generally are brightly colored in order to attract diurnal insects, such as butterflies.

Flowers with nocturnal anthesis generally are white or less colorful, and as such, they contrast more strongly with the night. These flowers typically attract nocturnal insects including many moth species.

Banksia ser. Spicigerae

Banksia ser. Spicigerae is a taxonomic series in the genus Banksia. It consists of the seven species in section Oncostylis that have cylindrical inflorescences. These range in form from small shrubs to tall trees. The leaves grow in either an alternate or whorled pattern, with various shape forms. The Spicigerae inflorescence is held erect, subtended by a whorl of branchlets, and retains a regular pattern until anthesis. The perianth limb is horizontal until anthesis, at which point the perianth opens from underneath. The pollen-presenter is ovoid or conical. The seed wings are not notched.

Brachychiton

Brachychiton (kurrajong, bottletree) is a genus of 31 species of trees and large shrubs, native to Australia (the centre of diversity, with 30 species), and New Guinea (one species). Fossils from New South Wales and New Zealand are estimated to be 50 million years old, corresponding to the Paleogene.

They grow to 4 – 30m tall, and some are dry-season deciduous. Several species (though not all) are pachycaul plants with a very stout stem for their overall size, used to store water during periods of drought. The leaves show intraspecific variation and generally range from entire to deeply palmately lobed with long slender leaflet-like lobes joined only right at the base. Their sizes range from 4 – 20 cm long and wide.

All species are monoecious with separate male and female flowers on the same plant. The flowers have a bell-shaped perianth consisting of a single series of fused lobes which is regarded as a calyx despite being brightly coloured in most species. The female flowers have five separate carpels that can each form a woody fruit containing several seeds. The flower colour is often variable within species. Eastern forest species drop their foliage before flowering but those of the drier regions carry the flowers while in leaf.

The name Brachychiton is derived from the Greek brachys, short, and chiton, tunic, in referring to its loose seed coats. The generic name is often misconstrued as being of neuter gender, with the specific epithets then incorrectly amended. Thus B. rupestre and B. populneum are sometimes seen in horticultural books and magazines.

Kurrajong comes from Dharuk garrajuŋ "fishing line", as fishing lines were made from kurrajong bark. A few Kurrajong species are popular garden trees and have been introduced to hot dry regions including the Mediterranean, South Africa and the western United States. These species are also hybridised for horticultural purposes, B. populneo-acerifolius being one example. Kurrajongs are known to bloom erratically in cultivation.

Floral diagram

Floral diagram is a graphic representation of flower structure. It shows the number of floral organs, their arrangement and fusion. Different parts of the flower are represented by their respective symbols. Floral diagrams are useful for flower identification or can help in understanding angiosperm evolution. They were introduced in the late 19th century and are generally attributed to A. W. Eichler.

Floral formula

Floral formula is a means to represent the structure of a flower using numbers, letters and various symbols, presenting substantial information about the flower in a compact form. It can represent particular species, or can be generalized to characterize higher taxa, usually giving ranges of organ numbers. Floral formulae are one of the two ways of describing flower structure developed during the 19th century, the other being floral diagrams. The format of floral formulae differs between authors, yet they tend to convey the same information.

Floral symmetry

Floral symmetry describes whether, and how, a flower, in particular its perianth, can be divided into two or more identical or mirror-image parts.

Uncommonly, flowers may have no axis of symmetry at all, typically because their parts are spirally arranged.

Flower

A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Magnoliophyta, also called angiosperms). The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs. Flowers may facilitate outcrossing (fusion of sperm and eggs from different individuals in a population) or allow selfing (fusion of sperm and egg from the same flower). Some flowers produce diaspores without fertilization (parthenocarpy). Flowers contain sporangia and are the site where gametophytes develop. Many flowers have evolved to be attractive to animals, so as to cause them to be vectors for the transfer of pollen. After fertilization, the ovary of the flower develops into fruit containing seeds.

In addition to facilitating the reproduction of flowering plants, flowers have long been admired and used by humans to bring beauty to their environment, and also as objects of romance, ritual, religion, medicine and as a source of food.

Glossary of botanical terms

This glossary of botanical terms is a list of terms relevant to botany and plants in general. Terms of plant morphology are included here as well as at the related Glossary of plant morphology and Glossary of leaf morphology. See also List of Latin and Greek words commonly used in systematic names. You can help by adding illustrations that assist an understanding of the terms.

Labellum (botany)

In botany, the labellum (or lip) is the part of the flower of an orchid or Canna, or other less-known genera that serves to attract insects, which pollinate the flower, and acts as a landing platform for them.

Labellum (plural: labella) is the Latin diminutive of labrum, meaning lip.

The labellum is a modified petal and can be distinguished from the other petals and from the sepals by its large size and its often irregular shape. It is not unusual for the other two petals of an orchid flower to look like the sepals, so that the labellum stands out as distinct.In orchids, the labellum is the modified median petal that sits opposite from the fertile anther and usually highly modified from the other perianth segments. It is often united with the column and can be hinged or movable, facilitating pollination. Often, the orchid labellum is divided into three or more lobes. Some have modified fleshy lumps on the upper surface generally referred to as the callus (plural: calli), with some being divided into multiple ridges or a central keel. When the callus is flat and broad, it is sometimes called a plate, which can have fringed margins. The callus can be highly modified with striking colors that may aid in pollinator deceit and mimicry.The labellum in orchids is often large and complex enough that terminology describing relative positions for structures on it becomes useful: the hypochile is the basal portion nearer the connection with the rest of the flower, the mesochile is the middle portion, and the epichile is the distal portion.

Leucospermum

Leucospermum is a genus of evergreen upright, sometimes creeping shrubs that is assigned to the Proteaceae, with currently forty-eight known species. Almost all species are easily recognised as Leucospermum because of the long protruding styles with a thickened pollen-presenter, which jointly give the flower head the appearance of a pincushion, its common name. Pincushions can be found in South Africa, Swaziland, Zimbabwe and Mozambique.

The shrubs mostly have a single stem at their base, but some species sprout from an underground rootstock, from which the plant can regrow after fire has killed the above ground biomass. In a larger group of species, specimens are killed by fire, and their survival depends on the seeds. In all species, seeds are collected by ants, which take them to their underground nests to feed on their ant breads, a seed dispersal strategy known as myrmecochory. This ensures that the seeds do not burn, so new plants can grow from them.

Leucospermum species mostly seated, simple, mostly leathery, often softly hairy leaves, set in a spiral, with entire margins or more often, with 3–17 blunt teeth with thickened, bony tips, and without stipules at their foot. The flowers are organised with many together in heads with bracts on the under- or outside. The hermaphrodite flowers themselves are set on a common base that may be cylindrical, conic or flat, and have small bracts at their base. The flowers have a perianth that is hairy on the outside, particularly at the tip, and consists of four tepals that are merged into a tube. Usually the four anthers are merged individually with the tip the perianth lobes, and only in a few species, a very short filament is present that further down cannot be distinguished from the tepals anymore. While still in the bud, the pollen is transferred from the anthers to the pollen-presenter, a thickening at the tip of the style. At that stage, the style grows considerably and rips through the sutures between the two perianth lobes facing away from the centre of the flower head. The perianth lobes all four remain attached to each other, or with three, or the four free lobes all curl back on themselves (like the lit of a sardine can), rimming the top of the tube. The superior ovary consists of one carpel and contains a single ovary, and is subtended by four small scales. The fruit is an oval or almost globe-shaped nut.

Most species have very limited ecological ranges and distribution areas, and many are rare or endagered. The often attractive, large flower heads and evergreen foliage, the straight stems, combined with long flowering period makes that Leucospermum species and their hybrids are bred as garden ornamental and cut flower.

List of Narcissus horticultural divisions

The Narcissus horticultural divisions are system of classifying the cultivated varieties of the genus Narcissus (), which are predominantly spring perennial plants in the Amaryllidaceae (amaryllis) family. Various common names including daffodil, narcissus, and jonquil are used to describe all or some members of the genus.

The list of Narcissus horticultural divisions provided by the Royal Horticultural Society (RHS) is the standard method used to classify and describe cultivated varieties (cultivars) of Narcissus. It is widely used since the RHS is the international authority for the registration of such cultivars. For horticultural purposes, all Narcissus cultivars are split into 13 divisions, as described by Kington (1998), for the RHS, based partly upon flower form (shape and length of corona – the "trumpet" or "cup"), particularly the ratio of corona to length of perianth segments (tepals or "petals"), the number of flowers per stem, flowering period and partly upon the genetic background. Division 11 (Split-corona) with its two subdivisions was the most recent group to be described (1969). Division 13, which includes all the wild rather than cultivated daffodils, is the exception to this scheme.

This classification is a useful tool for planning planting. Most commercially available narcissi come from Divisions 1 (Trumpet), 2 (Large-cupped) and 8 (Tazetta).Growers register new daffodil cultivars by name and colour with the RHS, whose International Daffodil Register is regularly updated with supplements available online and is searchable. The most recent supplement (2014) is the sixth; the fifth was published in 2012. More than 27,000 names were registered as of 2008, and the number has continued to grow. However, because of synonymy, the actual number is probably closer to 18,000; only about 500 are in commercial production (470 in 2009–2010).Registered daffodils are given a division number and colour code such as 5W-W ('Thalia'). In horticultural usage it is not uncommon to also find another unofficial division of 'Miniatures', which, although drawn from the other 13 divisions, have their miniature size in common. These are sometimes referred to by nurseries as 'Division 14'. Over 140 narcissus cultivars have gained the Royal Horticultural Society's Award of Garden Merit.

Myrsinaceae

Myrsinaceae, or the myrsine family, was formerly recognized as a rather large family from the order Ericales, consisting of 35 genera and about 1000 species. It is a widespread family found in temperate to tropical climates extending north to Europe, Siberia, Japan, Mexico, and Florida, and south to New Zealand, South America, and South Africa.

Plants are mostly mesophytic trees and shrubs; a few are lianas or subherbaceous. Their leathery, evergreen leaves are simple and alternate, with smooth margins and without stipules. They are often dotted with glands and resinous cavities. The latter may take the form of secretory lines.

The plants are mostly monoecious, but a few are dioecious. Their small flowers are arranged in racemose terminal clusters, or in the leaf axils. The flowers have four or five sepals and petals. The floral envelope (perianth) has a distinct calyx and corolla. The calyx is regular and polysepalous. The nonfleshy petals of the corolla are more or less united, closely overlapping. The four or five stamens are usually isomerous with the perianth. The carpel has one style and one stigma, with the ovary unilocular, superior or semi-inferior.

The one-seeded, indehiscent fruit is a thin-fleshed berry or drupe.

North American species are the marlberry (Ardisia escalloniodes) and the Florida rapanea (Rapanea punctata).

Plants in the myrsine family have few economic uses. A few genera, such as Ardisia, Cyclamen, Lysimachia, and Myrsine, are grown as ornamental plants, especially Ardisia crispa and Myrsine africana. One species, Ardisia japonica (Chinese: 紫金牛; pinyin: zǐjīn niú), is one of the 50 fundamental herbs in traditional Chinese medicine.

In the APG III system, the Myrsinaceae were not recognized, but were sunk into Primulaceae, which in that system is circumscribed very broadly.

Petal

Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals, that collectively form the calyx and lie just beneath the corolla. The calyx and the corolla together make up the perianth. When the petals and sepals of a flower are difficult to distinguish, they are collectively called tepals. Examples of plants in which the term tepal is appropriate include genera such as Aloe and Tulipa. Conversely, genera such as Rosa and Phaseolus have well-distinguished sepals and petals. When the undifferentiated tepals resemble petals, they are referred to as "petaloid", as in petaloid monocots, orders of monocots with brightly coloured tepals. Since they include Liliales, an alternative name is lilioid monocots.

Although petals are usually the most conspicuous parts of animal-pollinated flowers, wind-pollinated species, such as the grasses, either have very small petals or lack them entirely.

Sepal

A sepal ( or ) 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. The term sepalum was coined by Noël Martin Joseph de Necker in 1790, and derived from the Greek σκέπη (skepē), a covering.Collectively the sepals are called the calyx (plural calyces), the outermost whorl of parts that form a flower. The word calyx was adopted from the Latin calyx, not to be confused with calix, a cup or goblet. Calyx derived from the Greek κάλυξ (kalyx), a bud, a calyx, a husk or wrapping, (cf Sanskrit kalika, a bud) while calix derived from the Greek κύλιξ (kylix), a cup or goblet, and the words have been used interchangeably in botanical Latin.After flowering, most plants have no more use for the calyx which withers or becomes vestigial. Some plants retain a thorny calyx, either dried or live, as protection for the fruit or seeds. Examples include species of Acaena, some of the Solanaceae (for example the Tomatillo, Physalis philadelphica), and the water caltrop, Trapa natans. In some species the calyx not only persists after flowering, but instead of withering, begins to grow until it forms a bladder-like enclosure around the fruit. This is an effective protection against some kinds of birds and insects, for example in Hibiscus trionum and the Cape gooseberry. In other species, the calyx grows into an accessory fruit.

Morphologically, both sepals and petals are modified leaves. The calyx (the sepals) and the corolla (the petals) are the outer sterile whorls of the flower, which together form what is known as the perianth.The term tepal is usually applied when the parts of the perianth are difficult to distinguish, e.g. the petals and sepals share the same color, or the petals are absent and the sepals are colorful. When the undifferentiated tepals resemble petals, they are referred to as "petaloid", as in petaloid monocots, orders of monocots with brightly coloured tepals. Since they include Liliales, an alternative name is lilioid monocots. Examples of plants in which the term tepal is appropriate include genera such as Aloe and Tulipa. In contrast, genera such as Rosa and Phaseolus have well-distinguished sepals and petals.The number of sepals in a flower is its merosity. Flower merosity is indicative of a plant's classification. The merosity of a eudicot flower is typically four or five. The merosity of a monocot or palaeodicot flower is three, or a multiple of three.

The development and form of the sepals vary considerably among flowering plants. They may be free (polysepalous) or fused together (gamosepalous). Often, the sepals are much reduced, appearing somewhat awn-like, or as scales, teeth, or ridges. Most often such structures protrude until the fruit is mature and falls off.

Examples of flowers with much reduced perianths are found among the grasses.

In some flowers, the sepals are fused towards the base, forming a calyx tube (as in the Lythraceae family, and Fabaceae). In other flowers (e.g., Rosaceae, Myrtaceae) a hypanthium includes the bases of sepals, petals, and the attachment points of the stamens.

Spikelet

A spikelet, in botany, describes the typical arrangement of grass flowers.

Each spikelet has one or more florets. The spikelets are further grouped into panicles or spikes. The part of the spikelet that bears the florets is called the rachilla. A spikelet consists of two (or sometimes fewer) bracts at the base, called glumes, followed by one or more florets. A floret consists of the flower surrounded by two bracts, one external—the lemma—and one internal—the palea. The perianth is reduced to two scales, called lodicules, that expand and contract to spread the lemma and palea; these are generally interpreted to be modified sepals.

The flowers are usually hermaphroditic—maize being an important exception—and mainly anemophilous or wind-pollinated, although insects occasionally play a role.

Tepal

A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of very similar appearance), as in Magnolia, or because, although it is possible to distinguish an outer whorl of sepals from an inner whorl of petals, the sepals and petals have similar appearance to one another (as in Lilium). The term was first proposed by Augustin Pyramus de Candolle in 1827 and was constructed by analogy with the terms "petal" and "sepal". (De Candolle used the term perigonium or perigone for the tepals collectively; today this term is used as a synonym for "perianth".)

Zelkova

Zelkova (from Georgian ძელქვა (dzelkva) - stone pillar) is a genus of six species of deciduous trees in the elm family Ulmaceae, native to southern Europe, and southwest and eastern Asia. They vary in size from shrubs (Z. sicula) to large trees up to 35 m (115 ft) tall (Z. carpinifolia). The bark is smooth, dark brown. Unlike the elms, the branchlets are never corky or winged. The leaves are alternate, with serrated margins, and (unlike the related elms) a symmetrical base to the leaf blade. The leaves are in two distinct rows; they have pinnate venation and each vein extends to the leaf margin, where it terminates in a tooth. There are two stipules at each node, though these are caducous (shed early), leaving a pair of scars at the leaf base. Zelkova is polygamous. Staminate flowers are clustered in the lower leaf axils of young branchlets; the perianth is campanulate, with four to six (to seven) lobes, and the stamens are short. Pistillate and hermaphrodite flowers are solitary, or rarely in clusters of two to four, in the upper leaf axils of young branchlets. The fruit is a dry, nut-like drupe with a dorsal keel, produced singly in the leaf axils. The perianth and stigma are persistent.

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