Commelina communis (Asiatic Dayflower)
|Also known as:|
|Habitat:||part shade, shade; moist soil; waste areas, roadsides, edges of woods, thickets|
|Bloom season:||July - October|
|Plant height:||1 to 3 feet|
|Wetland Indicator Status:||GP: FAC MW: FACU NCNE: FAC|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Stalked flowers, single or in small clusters, at the tips of branching stems and arising from leaf axils near the top of the plant. Individual flowers are ½ to 1 inch across and have 3 petals. The upper 2 petals are round and bright blue; the lower petal is much smaller, white and notched into 3 rounded lobes. In the center are 3 small, sterile stamens and a 4th stamen with a larger, butterfly-shaped tip, all 4 typically with a spot of maroon in the center of the yellow tip. Below are a style and 2 fertile stamens; all 3 are long, curving and white to yellowish.
Behind the flower is a folded, leafy bract (spathe) that is up to 2 inches long and half heart-shaped in outline. The spathe is hairless and open at the top all the way to its base. Each flower lasts for a single day, hence the common name.
Leaves and stem:
Leaves are up to 5 inches long and 2 inches wide, lance-elliptic with pointed tips, a rounded base, no stalk, faint parallel lines along the length, toothless, hairless but may be rough textured on the upper surface, and widely spaced on the stem.
The leaf base extends to form a sheath up to 1 inch long, surrounding the stem, with a few long hairs around the tip edge and short hairs along the front seam but otherwise hairless. Stems are hairless, erect or prostrate but rising at the tip (decumbent), usually rooting at the nodes.
Asiatic Dayflower is a potentially invasive weed much more common to our south and east, though its presence in the Upper Midwest is growing. There is a similar species, Slender Dayflower (Commelina erecta), a rare native, which (so far) has only been recorded in Minnesota in Wabasha County. Its spathe is fused at the top for most of its length, has narrower leaves, the yellow stamens lack the maroon spot, and is variously covered in stiff hairs on spathes, leaves, sheaths and stem, where Asiatic Dayflower is mostly hairless.
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Photos by K. Chayka taken at Long Lake Regional Park, Ramsey County.
Have you seen this plant in Minnesota, or have any other comments about it?