The dayflowers are herbs that may be either perennial or annual. They are characterised by their zygomorphic flowers and by the involucral bracts called spathes that surround the flower stalks. These spathes are often filled with a mucilaginous liquid. Each spathe houses either 1 or 2 scorpioid cymes, with the upper cyme being either vestigial or bearing 1 to several 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. It grows happily in fairly urban environments, often colonizing neglected gardens. It can be seen growing among garden periwinkle plants, perhaps because the superficial similarity of their stems and leaves makes it harder to weed out.
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