Commelina diffusa
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| Commelina diffusa Burman |
Commelina diffusa, sometimes known as the climbing dayflower or spreading dayflower, is a pantropical herbaceous plant in the dayflower family. It has been introduced to the southeastern United States where it is most common in wet disturbed soils. There are two recognised varieties, one being the type and the other being C. diffusa var. gigas, which is native to Asia and has been introduced to Florida. It flowers from spring to fall and is most common in disturbed situations, moist places and forests. In China the plant is used medicinally as a febrifuge and a diuretic. A blue dye is also extracted from the flower for paints.
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[edit] Description
Commelina diffusa is typically an annual herb, though it may be perennial in the tropics.[1] It spreads diffusely, creeping along the ground, branching heavily and rooting at the nodes, obtaining stem lengths up to 1 metre. Pubescence on the stem is variable and ranges from glabrous to hispidulous, which can occur either in a line or throughout.[2] The leaf blades are relatively variable, ranging from lanceolate to ovate,[1] with proximal leaves tending to be more oblong. They measure 3 to 12 cm in length by 0.8 to 3 cm in width.[2] North American populations tend to have smaller leaf size, typically measuring 1.5 to 5 cm, by 0.5 by 1.8 cm. The leaf apex is acute to acuminate.[1] The leaf surface can be either glabrous (i.e. hairless) or hispid (i.e. bristly). The leaves are subsessile (i.e. having a very small petiole) with a leaf sheath striped with red and covered with hispid pubescence. Folded involucral bracts appear opposite to the leaves and are between ovate (i.e. egg-shaped) and lanceolate in shape and measure 1 to 4 cm long. The bracts have a cordate (i.e. heart-shaped) to rounded base, acuminate apices and can be either glabrous or hispidulous (i.e. minutely hispid) beneath.[2]
The flowers are arranged into cincinni (singular: cincinnus), or scorpioid cymes. This is a form of a monochasium where the lateral branches arise alternately on opposite sides of the false axis. There are typically 2 cincinni present, with the lower cincinnus bearing 2 to 4 flowers, while the upper cincinnus has 1 to several flowers. The upper cincinnus is generally exerted on specimens with larger spathes, but it may be included in specimens with smaller spathes.[1] The upper cincinnus bears only male flowers and has a longer peduncle, while the lower cincinnus bears bisexual flowers on a shorter peduncle. The pedicels supporting single flowers, and later the fruits, are thick and curved and measure about 3 to 5 mm. The membranous sepals are inconspicuous at only 3 to 4 mm in length.[2] The petals are blue, though may be lavender in rare cases.[1] The upper two petals measure 4.2 to 6 mm.[2] The anther connective (i.e. the tissue connecting the two halfs of the anther) of the centre-most stamen has a broad transverse band of violet. The spathes are soliatary, borne on a peduncle and typically falcate (i.e. sickle-shaped). They usually measure 0.8 to 2.5 cm long, but may be as short as 0.5 cm and as long as 3.7 cm. They are typically 0.4 by 1.2 cm wide, but may be up to 1.4 cm long. Their peduncles are usually 0.5 to 2 cm long and rarely up to 2.9 cm.[1] Flowering occurs from May to November.[2]
The fruit is a capsule which has 3 locules and 2 valves. It measures 4 to 6.3 mm long by 3 to 4 mm wide, though it may be as narrow as 2.1 mm. They contain 5 brown seeds that are 2 to 2.8, rarely up to 3.2 mm long, by 1.4 to 1.8 mm wide. They are deeply reticulate (i.e. net-like). The chromosome number is 2n = 30.[1]
[edit] Distribution and habitat
The plant is present in tropical and subtropical locations worldwide. It can be found throughout much of southern China, specifically in the provinces of Guangdong, southwestern Guangxi, southwestern Guizhou, Hainan, southeasten Xizang and southeastern Yunnan.[2] It is native in parts of the West Indies, including much of Puerto Rico and several of the Virgin Islands such as Saint Croix, Saint Thomas and Tortola.[3] It has also been introduced to the southeastern United States where it is present from Maryland in the north, west to Missouri and south to Texas and Florida. It has also been introduced to Hawaii. The variety C. diffusa var. gigas has been introduced to Florida.[1]
In China it can be found from sea level up to 2100 metres, and is typically associated with forests, thickets, stream banks and other open and humid habitats.[2] In the West Indies it is a common weed that is especially associated with roadsides, moist ditches and waste places and it can be found from sea level to 1050 metres.[3] In the Unites States it is also typical of disturbed locations, such as gardens, cultivated areas and lawns, but can also be found in woods and other moist situations.[1]
[edit] Uses
Within China, Commelina diffusa is used as a medicinal herb with febrifugal and diuretic effects. A dye is also obtained from the juice of the petals for use in painting.[2]
[edit] References
- ^ a b c d e f g h i Faden, Robert (2006), “Commelina diffusa”, in Flora of North America Editorial Committee, eds. 1993+, Flora of North America online, vol. 22, New York & Oxford: Oxford University Press
- ^ a b c d e f g h i Hong, Deyuan; DeFillipps, Robert A. (2000), “Commelina diffusa”, in Wu, Z. Y.; Raven, P.H.; Hong, D.Y., Flora of China, vol. 24, Beijing: Science Press; St. Louis: Missouri Botanical Garden Press, pp. 36
- ^ a b Acevedo-Rodriguez, Pedro; Strong, Mark T. (2005), “Monocotyledons and Gymnosperms of Puerto Rico and Virgin Islands”, Contributions of the United States National Herbarium 52: 158
[edit] External links
Media related to Commelina diffusa from the Wikimedia Commons.- Profile at Flora of Missouri Webpage
- Profile at USDA PLANTS Database
