A tepal is one of the outer parts of a

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 ...

(collectively the

perianth The perianth (perigonium, perigon or perigone in monocots) 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) or tepals when ...

). The term is used when these parts cannot easily be classified as either

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 coined b ...

s or

petal Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...

s. This may be because the parts of the perianth are undifferentiated (i.e. of very similar appearance), as in ''

Magnolia ''Magnolia'' is a large genus of about 210 to 340The number of species in the genus ''Magnolia'' depends on the taxonomic view that one takes up. Recent molecular and morphological research shows that former genera ''Talauma'', ''Dugandiodendro ...

'', or because, although it is possible to distinguish an outer

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral ...

of sepals from an inner whorl of petals, the sepals and petals have similar appearance to one another (as in ''

Lilium ''Lilium'' () is a genus of herbaceous flowering plants growing from bulbs, all with large prominent flowers. They are the true lilies. Lilies are a group of flowering plants which are important in culture and literature in much of the world. M ...

''). The term was first proposed by

Augustin Pyramus de Candolle Augustin Pyramus (or Pyrame) de Candolle (, , ; 4 February 17789 September 1841) was a Swiss botanist. René Louiche Desfontaines launched de Candolle's botanical career by recommending him at a herbarium. Within a couple of years de Candol ...

in 1827 and was constructed by

analogy Analogy (from Greek ''analogia'', "proportion", from ''ana-'' "upon, according to" lso "against", "anew"+ ''logos'' "ratio" lso "word, speech, reckoning" is a cognitive process of transferring information or meaning from a particular subject ( ...

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''.) p. 39.

Origin

Undifferentiated tepals are believed to be the ancestral condition in

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. For example, '' Amborella'', which is thought to have separated earliest in the evolution of flowering plants, has flowers with undifferentiated tepals. Distinct petals and sepals would therefore have arisen by differentiation, probably in response to animal

pollination Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds ...

. In typical modern flowers, the outer or enclosing whorl of organs forms sepals, specialised for protection of the flower bud as it develops, while the inner whorl forms petals, which attract

pollinator A pollinator is an animal that moves pollen from the male anther of a flower to the female stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insects are the maj ...

s. Tepals formed by similar sepals and petals are common in

monocotyledon Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of ...

s, particularly the "

lilioid monocot Lilioid monocots (lilioids, liliid monocots, petaloid monocots, petaloid lilioid monocots) is an informal name used for a grade (grouping of taxa with common characteristics) of five monocot orders (Petrosaviales, Dioscoreales, Pandanales, Lil ...

s". In

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, for example, the first and second whorls both contain structures that look like petals. These are fused at the base to form one large, showy, six-parted structure (the perianth). In

lilies ''Lilium'' () is a genus of herbaceous flowering plants growing from bulbs, all with large prominent flowers. They are the true lilies. Lilies are a group of flowering plants which are important in culture and literature in much of the world. M ...

the organs in the first whorl are separate from the second, but all look similar, thus all the showy parts are often called tepals. Where sepals and petals can in principle be distinguished, usage of the term "tepal" is not always consistent – some authors will refer to "sepals and petals" where others use "tepals" in the same context. In some plants the flowers have no petals, and all the tepals are sepals modified to look like petals. These organs are described as

petaloid Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corolla''. Petals are usually ...

, for example, the sepals of

hellebore Commonly known as hellebores (), the Eurasian genus ''Helleborus'' consists of approximately 20 species of herbaceous or evergreen perennial flowering plants in the family Ranunculaceae, within which it gave its name to the tribe of Helleboreae. ...

s. When the undifferentiated tepals resemble petals, they are also referred to as "petaloid", as in

petaloid monocots Lilioid monocots (lilioids, liliid monocots, petaloid monocots, petaloid lilioid monocots) is an informal name used for a grade (biology), grade (grouping of taxa with common characteristics) of five monocot order (biology), orders (Petrosavial ...

, orders of monocots with brightly coloured tepals. Since they include Liliales, an alternative name is lilioid monocots.

Properties and shape

Terms used in the description of tepals include pubescent (with dense fine, short, soft hairs, downy), puberulent (minutely pubescent, hairs barely visible to the naked eye) and puberulous (dense covering of very short soft hairs). Tepal shape is described in similar terms to those used for leaves (see

Glossary of leaf morphology The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...

Gallery

File:Magnolia-x-alba-bud-comparison.jpg, Flowers of ''Magnolia'' × ''alba'' showing tepals in various stages of development File:Magnolia wieseneri.jpg, Tepals of ''Magnolia'' × ''wieseneri'' File:2006-12-18Helleborus_niger19.jpg, A

flower showing the petaloid sepals File:Sternbergia lutea showing the different parts of the flower.JPG, A '' Sternbergia lutea'' flower showing the two whorls of tepals File:Tulip_-_floriade_canberra02.jpg, A tulip flower showing the petal-like tepals File:Blandfordia_nobilis_Berowra_Valley.JPG, Tepals of ''

Blandfordia nobilis ''Blandfordia nobilis'', commonly known as Christmas bells or gadigalbudyari in Cadigal language, is a flowering plant endemic to New South Wales. It is a tufted, perennial herbs with narrow, linear leaves and between three and twenty large, dr ...

'', another

References

''Botany: A Brief Introduction To Plant Biology'' - 5th ed. Thomas L. Rost; T. Elliot Weier - Wiley & Sons 1979 . ''Plant Systematics'' - Jones; Samuel - McGraw-Hill 1979 . {{botany Plant morphology

Origin

Properties and shape

Gallery

See also

References