Look up perianth in Wiktionary, the free dictionary.

In a general sense, a tepal is an element of the perianth of a flower, such as a petal or sepal. The perianth comprises the outer, sterile whorls of a flower. The term tepal is usually used when all segments of a perianth are of similar shape and color (that is, undifferentiated). Wikipedia does not have an article with this exact name. ... Wiktionary is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ... The perianth is the outer envelope of a flower. ... A Phalaenopsis flower A flower, (<Old French flo(u)r<Latin florem<flos), also known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Magnoliophyta, also called angiosperms). ... It has been suggested that Corolla be merged into this article or section. ... Flower of the Primrose Willowherb (Ludwigia octovalvis) showing petals and sepals A sepal is one member or part of the calyx of a flower. ...

Examples of plants with undifferentiated tepals include:

• The family Magnoliaceae
• The Amborellaceae and Calycanthaceae, primitive flowering plants
• The Hellebore family
• Many monocots, such as lilies and tulips.

Genera Magnolioideae Elmerillia (4 species) Kmeria (5 species) Magnolia (128 species) Manglietia (29 species) Michelia (49 species) Pachylarnax (2 species) Liriodendroidae Liriodendron (2 species) The Magnoliaceae is a family in the flowering plant Order Magnoliales. ... Binomial name Amborella trichopoda Baill. ... Genera Calycanthus Chimonanthus Idiospermum Sinocalycanthus The Calycanthaceae (sweetshrub or spicebush family) is a small family of flowering plants included in the order Laurales. ... Species See text(#Species) Hellebores (the Genus Helleborus in the Family Ranunculaceae) are perennial flowering plants that are often grown in gardens for decorative purposes, as well as for their purported medicinal abilities and uses in witchcraft. ... Orders Base Monocots: Acorus Alismatales Asparagales Dioscoreales Liliales Pandanales Family Petrosaviaceae Commelinids: Arecales Commelinales Poales Zingiberales Family Dasypogonaceae The Monocotyledons or monocots are an extremely important group of flowering plants, dominating great parts of the earth and with many economically important plants. ... Species See text The plants of the genus Lilium are the true lily plants, comprising a genus of about 100 species in the lily family, Liliaceae. ... Species See text Tulip (Tulipa) is a genus of about 100 species of flowering plants in the family Liliaceae. ...

Evolutionary significance

As undifferentiated tepals appear in some of the most primitive flowering plants, they are likely to have preceded differentiated sepals and petals. It may therefore be the case that petals and sepals have evolved by differentiation of tepals, in response to animal pollination. Once two distinct whorls of tepals were present, the outer could become specialised for protecting the flower during development (sepals), and the inner, for attracting animal pollinators (petals). Flower of the Primrose Willowherb (Ludwigia octovalvis) showing petals and sepals A sepal is one member or part of the calyx of a flower. ... It has been suggested that Corolla be merged into this article or section. ... Zoophily is a form of pollination whereby pollen is distributed by animals, particularly by hummingbirds and bats, but also passively by bears, rabbits, deer, and other furred animals. ...

However, it is also possible that petals evolved from stamens. It may be the case that differentiated petals and sepals arose independently, several times, and are therefore an example of convergent evolution. Flower of the spider tree (Crateva religiosa) with its numerous conspicuous stamens The stamen is the male organ of a flower. ... It has been suggested that Morphological convergence be merged into this article or section. ...

Merosity

Merosity is a property of whorls of floral perianths that relates how many tepals a whorl of that particular plant has. Types of merosity, according to number of tepals in a perianth whorl, include:

• dimery (2)
• trimery (3)
• tetramery (4)
• pentamery (5)

These nouns for the different types of merosity are formed by a prefix derived from Ancient Greek (e.g. tetra- for four tepals) and the suffixed root, -mery, which is derived from Greek meros meaning "part". Tetrameric flower of the primrose willowherb (Ludwigia octovalvis) showing four petals and four sepals In describing a flower, tetramery means that the flower parts are in fours: such as four petals in the crown. ... Note: This article contains special characters. ...

References

• E M Kramer, R L Dorit, and V F Irish (1998). Molecular evolution of genes controlling petal and stamen development: duplication and divergence within the APETALA3 and PISTILLATA MADS-box gene lineages. Genetics. 1998 June; 149(2): 765–783.