Commelina
Encyclopedia
Commelina is a genus of approximately 170 species commonly called dayflowers due to the short lives of their flowers. They are less often known as widow's tears. It is by far the largest genus of its family, Commelinaceae
. The Swedish taxonomist Carl Linnaeus of the 18th century named the genus after the two Dutch botanists Jan Commelijn and his nephew Caspar
, each representing one of the showy petals of Commelina communis
.
The dayflowers are herbs that may be either perennial or annual. They are characterised by their zygomorphic flowers and by the involucral bract
s called spathes that surround the flower stalks. These spathes are often filled with a mucilaginous liquid. Each spathe houses either one or two scorpioid cymes, with the upper cyme being either vestigial or bearing from one to several typically male flowers, and the lower cyme bearing several flowers. All members of the genus have alternate leaves.
The Asiatic dayflower (Commelina communis
) is probably the best known species in the West. It is a common weed
in parts of Europe
and throughout eastern North America
. Several species, such as Commelina benghalensis
, are eaten as a leaf vegetable
in Southeast Asia
and Africa
.
ous or rhizomatous
. The leaves are distichous (i.e. 2-ranked) or spirally arranged with blades that either lack or have a petiole. The ptyxis, or the way the leaf is folded in the bud, is either involute (i.e. having inrolled margins) or supervolute.
The inflorescence
s are terminal, meaning the stem terminates with an inflorescence, and often leaf opposed, meaning it emerges at the node with a leaf of a new axiallary stem. The inflorescence is composed of one or two cincinni, also called scorpioid cymes, which are monochasiums (i.e. cymes with a single branched main false axis) in which the lateral branches arise alternately on opposite sides of the false axis. The distal cincinnus may either be vestigial or contain one to several flowers that are typically male. The proximal cyme is always present and is multi-flowered. The cincinni are enclosed in a folded spathe, a modified leaf, which is often filled with a mucilaginous liquid. The spathe may either have completely distinct margins or they may be fused to varying degrees at the basal end.
The flowers are borne on pedicel
s and are strongly zygomorphic, meaning there is only a single plane of symmetry. Bract
eoles occasionally subtend the pedicels, but they are usually absent. The flowers are either bisexual or male. There are three unequal sepal
s, which may either be free or the two lateral ones may be fused. The petal
s are free and unequal with the two upper ones being larger and clawed while the lower petal is typically reduced and often differs in colour from the other two. Flower colour is most typically blue, but lilac, lavender, yellow, peach, apricot and white also occur. There are three stamen
s and two to three staminodes, or infertile stamens, all of which have free, glabrous filaments. The staminodes occur posteriorly and have antherodes with four to six lobes. The stamens are anterior and are longer than the staminodes. The medial stamen differs in size and form from the lateral two, and when a central staminode is present it also differs from the other staminodes. The ovaries are bi- or trilocular
and one to two ovule
s is present per locule.
The fruit
is a capsule
that is typically bi- or trilocular
, but in rare cases may be unilocular, and it is bi- or trivalved. The locules may contain one or two seeds, or no seed at all. The seeds are uniserriate (i.e. arranged in a single row), have a linear hilum
and a lateral embryotega.
Commelinaceae
Commelinaceae is a family of flowering plants. In less formal contexts, the group is referred to as the dayflower family or spiderwort family. It is one of five families in the order Commelinales and by far the largest of these with an estimated 650 species in 40 genera. Well known genera include...
. The Swedish taxonomist Carl Linnaeus of the 18th century named the genus after the two Dutch botanists Jan Commelijn and his nephew Caspar
Caspar Commelijn
Caspar Commelijn or Caspar Commelin , was a Dutch botanist. He was the son of the bookseller, historian and publisher, Casparus Commelijn and his first wife, Margrieta Heydanus...
, each representing one of the showy petals of Commelina communis
Commelina communis
Commelina communis, commonly known as the Asiatic dayflower, is an herbaceous annual plant in the dayflower family. It is native throughout much of East Asia and northern parts of Southeast Asia. In China, the plant is known as yazhicao , roughly translating to "duckfoot herb", while in Japan it...
.
The dayflowers are herbs that may be either perennial or annual. They are characterised by their zygomorphic flowers and by the involucral bract
Bract
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 often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
s called spathes that surround the flower stalks. These spathes are often filled with a mucilaginous liquid. Each spathe houses either one or two scorpioid cymes, with the upper cyme being either vestigial or bearing from one to several typically male flowers, and the lower cyme bearing several flowers. All members of the genus have alternate leaves.
The Asiatic dayflower (Commelina communis
Commelina communis
Commelina communis, commonly known as the Asiatic dayflower, is an herbaceous annual plant in the dayflower family. It is native throughout much of East Asia and northern parts of Southeast Asia. In China, the plant is known as yazhicao , roughly translating to "duckfoot herb", while in Japan it...
) is probably the best known species in the West. It is a common weed
Weed
A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...
in parts of Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and throughout eastern North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. Several species, such as Commelina benghalensis
Commelina benghalensis
Commelina benghalensis, commonly known as the Benghal dayflower or tropical spiderwort, is a perennial herb native to tropical Asia and Africa. It has been widely introduced to areas outside its native range, including to the neotropics, Hawaii, the West Indies and to both coasts of North America...
, are eaten as a leaf vegetable
Leaf vegetable
Leaf vegetables, also called potherbs, green vegetables, greens, leafy greens or salad greens, are plant leaves eaten as a vegetable, sometimes accompanied by tender petioles and shoots...
in Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
and Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
.
Description
Plants in the genus are perennial or annual herbs with roots that are usually fibrous or rarely tuberTuber
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction...
ous or rhizomatous
Rhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...
. The leaves are distichous (i.e. 2-ranked) or spirally arranged with blades that either lack or have a petiole. The ptyxis, or the way the leaf is folded in the bud, is either involute (i.e. having inrolled margins) or supervolute.
The inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
s are terminal, meaning the stem terminates with an inflorescence, and often leaf opposed, meaning it emerges at the node with a leaf of a new axiallary stem. The inflorescence is composed of one or two cincinni, also called scorpioid cymes, which are monochasiums (i.e. cymes with a single branched main false axis) in which the lateral branches arise alternately on opposite sides of the false axis. The distal cincinnus may either be vestigial or contain one to several flowers that are typically male. The proximal cyme is always present and is multi-flowered. The cincinni are enclosed in a folded spathe, a modified leaf, which is often filled with a mucilaginous liquid. The spathe may either have completely distinct margins or they may be fused to varying degrees at the basal end.
The flowers are borne on pedicel
Pedicel (botany)
A pedicel is a stem that attaches single flowers to the main stem of the inflorescence. It is the branches or stalks that hold each flower in an inflorescence that contains more than one flower....
s and are strongly zygomorphic, meaning there is only a single plane of symmetry. Bract
Bract
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 often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
eoles occasionally subtend the pedicels, but they are usually absent. The flowers are either bisexual or male. There are three unequal sepal
Sepal
A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...
s, which may either be free or the two lateral ones may be fused. The petal
Petal
Petals are modified leaves that surround the reproductive parts of flowers. They often are 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 lying...
s are free and unequal with the two upper ones being larger and clawed while the lower petal is typically reduced and often differs in colour from the other two. Flower colour is most typically blue, but lilac, lavender, yellow, peach, apricot and white also occur. There are three stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...
s and two to three staminodes, or infertile stamens, all of which have free, glabrous filaments. The staminodes occur posteriorly and have antherodes with four to six lobes. The stamens are anterior and are longer than the staminodes. The medial stamen differs in size and form from the lateral two, and when a central staminode is present it also differs from the other staminodes. The ovaries are bi- or trilocular
Locule
A locule is a small cavity or compartment within an organ or part of an organism ....
and one to two ovule
Ovule
Ovule means "small egg". In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: The integument forming its outer layer, the nucellus , and the megaspore-derived female gametophyte in its center...
s is present per locule.
The fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
is a capsule
Capsule (fruit)
In botany a capsule is a type of simple, dry fruit produced by many species of flowering plants. A capsule is a structure composed of two or more carpels that in most cases is dehiscent, i.e. at maturity, it splits apart to release the seeds within. A few capsules are indehiscent, for example...
that is typically bi- or trilocular
Locule
A locule is a small cavity or compartment within an organ or part of an organism ....
, but in rare cases may be unilocular, and it is bi- or trivalved. The locules may contain one or two seeds, or no seed at all. The seeds are uniserriate (i.e. arranged in a single row), have a linear hilum
Hilum (biology)
In botany, the hilum is a scar or mark left on a seed coat by the former attachment to the ovary wall or to the funiculus...
and a lateral embryotega.