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.
Commelina communis, commonly known as the Asiatic dayflower, is an herbaceous annual plant in the dayflower family. It gets its name because the blooms last for only one day. 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 known as tsuyukusa, meaning "dew herb". It has also been introduced to parts of central and southeastern Europe and much of eastern North America, where it has spread to become a noxious weed. It is common in disturbed sites and in moist soil. The flowers emerge from summer through fall and are distinctive with two relatively large blue petals and one very small white petal.
Aneilema is a genus of monocotyledonous plants of approximately 60 species. The vast majority of the species are native to sub-Saharan Africa, but a few are found in Oceania and one, Aneilema brasiliense, is from South America. It is the third largest genus in the family Commelinaceae after Commelina and Tradescantia, and it is one of only six genera in the family to occur in both the Eastern Hemisphere and the Western Hemisphere.
Commelina caroliniana, sometimes known as the Carolina dayflower, is an herbaceous plant in the dayflower family native to India and Bangladesh. Both the scientific name and the common name are misleading as the plant was described based on specimens found in the southeastern United States before it was known that the plant had in fact been introduced from India. It was most likely introduced to South Carolina in the late 17th century along with rice seed from India. The plant has also been recently reported from South Korea. Its flowers emerge from summer to fall and rarely into the winter.
Commelina benghalensis, commonly known as the Benghal dayflower, tropical spiderwort, or wandering Jew, kanshira in Bengali, 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. It has a long flowering period, from spring to fall in subtropical areas, and throughout the year closer to the equator. It is often associated with disturbed soils.
Commelina cyanea, commonly known as scurvy weed, is a perennial prostrate herb of the family Commelinaceae native to moist forests and woodlands of eastern Australia, Lord Howe Island and Norfolk Island. The blue flowers appear over the warmer months and are pollinated by bees and flies.
Commelina mascarenica is a monocotyledonous, herbaceous plant in the dayflower family from East Africa. This pale blue-flowered herb is found in a variety of open habitats from open bush to roadsides. Although the species was originally thought to be restricted to Madagascar and the Comoro Islands, further study revealed that the species is also widely distributed along the East African coast from Somalia south to Mozambique. It had formerly been confused with the closely related species Commelina imberbis and Commelina lukei, the latter occurring alongside C. mascarenica throughout much of its range.
Commelina kotschyi is a monocotyledonous, herbaceous plant in the dayflower family from Africa and India. This annual, blue-flowered plant is found primarily in seasonally waterlogged soils at relatively high elevations. The species has been largely confused in floras, often being misinterpreted as Commelina imberbis. C. kotschyi is most closely related to Commelina lukei, with which it does not overlap in distribution. C. kotschyi is characterised by its appendaged seeds, capsules with a bulging apex, and undulate leaves, among other features.
Commelina sphaerorrhizoma is a monocotyledonous, herbaceous plant in the dayflower family from south-central Africa. This blue-flowered herb has been recorded from western Zambia, central Angola, and the southern portion of the Democratic Republic of the Congo, although at the time of its description it was known only from 11 collections and may be more broadly distributed. It is found in a variety of habitats ranging from woodlands to grasslands to roadsides. The plant's most distinctive feature and the source of its scientific name is its moniliform rhizome composed of spherical segments that can form a bead-like chain. Other distinguishing characteristics include glaucous leaves with clasping bases, unfused and virtually hairless spathes, capsules composed of three, one-seeded locules, and very large seeds with a hairy surface.
Commelina orchidophylla is a monocotyledonous, herbaceous plant in the dayflower family from south-central Africa. This blue-flowered herb has been recorded only from the Haut-Katanga District of the Democratic Republic of the Congo, although at the time of its description it was known only from 3 collections. It is found in woodlands, especially in rocky areas, and on sandstone. The plant's most distinctive feature and the source of its scientific name is its orchid-like pair of broad basal leaves. Other distinctive characteristics include hairy tuberous roots, solitary spathes on long stalks that arise directly from the basal leaves before the development of elongated flowering shoots, dimorphic seeds, and unfused spathes lacking hairs which contain an upper cincinnus that barely emerges. The flowers have never been observed directly and are only partially known from bud dissections.
Cartonema is a genus of perennial or annual monocotyledonous flowering plants in the dayflower family. It is restricted to Australia and nearby Trangan Island, which is part of Indonesia. It is the earliest diverging member of its family and has a number of traits that are unique within it, such as non-succulent leaves and a lack of raphides. Its distinctive features led to the genus to once be considered part of its own separate family, Cartonemataceae. However, analysis of DNA sequences, as well as many common anatomical characters, has supported its relationship with the Commelinaceae. It contains about 11 species.
Commelina grossa is an herbaceous plant in the dayflower family found in the East and Southern African countries of Tanzania, Malawi, and Zambia. The species is easily recognised by its mainly basal leaves which are long and linear, and its spathes, which lack hairs and are quite large. The petals are mauve-blue with the lower petal being highly reduced and the sepals fused into a cup. These features suggest it may be related to Commelina schweinfurthii and its allies, which share many of the same floral characters. The species' typical habitat is in woodland on sandy soil or soils that become seasonally waterlogged. Flowering occurs in April and June.
Commelina fluviatilis is an herbaceous plant in the dayflower family found primarily in Central Africa. It is known from Tanzania, the Democratic Republic of the Congo, Zambia, and the Caprivi Strip region of Namibia.
Commelina welwitschii is an herbaceous plant in the dayflower family found in Southern Africa from Zimbabwe to Angola. A phylogenetic study based on the nuclear ribosomal DNA region 5S NTS and the chloroplast region trnL-trnF, two commonly used gene regions for determining relationships, revealed that Commelina welwitschii forms a clade with Commelina purpurea and Commelina fluviatilis. Both of these relatives are African, share an unusual leaf anatomy, and have linear leaves that are often folded. Although it has yellow flowers, this study did not find a close relationship with Commelina capitata or Commelina africana, the two other African yellow-flowered species. Robert Faden, an expert on the Commelinaceae, points out that Commelina welwitschii is one of only three species in the genus to have bead-like rhizomes along with Commelina crassicaulis and Commelina sphaerorrhizoma. While it is clear that the former species is most likely a close relative given its many other similarities, the latter species is unlikely closely related given major differences in other characters.
Commelina eckloniana is an herbaceous plant in the dayflower family with a broad distribution in Central and East Africa.
Commelina polhillii is a plant species native to Tanzania, known only from the Iriniga and Mpanda Districts. It occurs in open woodlands and in disturbed sites.
Commelina zenkeri is a plant species native to tropical Africa. It is known from Uganda and Cameroon. Unconfirmed reports place it in Democratic Republic of the Congo as well. It grows on rocky hillsides in evergreen tropical forests at elevations up to 1300 m.
Commelina africana, the common yellow commelina, is a widespread species of flowering plant in the family Commelinaceae. It is native to Sub‑Saharan Africa, Madagascar, Réunion, and the Arabian Peninsula, and has been introduced to India. It is occasionally consumed as a leaf vegetable, and occasionally fed to rabbits and pigs.
