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Summary
Whitemouth dayflower is a grass-like perennial of warm-season habitats that is widespread across the southern and eastern United States and extends into the Southwest. Despite belonging to a genus that includes edible species in other regions, whitemouth dayflower itself is not well documented as a food plant, and its edible use remains uncertain. In contrast, a closely related southwestern species, birdbill dayflower (Commelina dianthifolia), produces small but excellent edible roots and mild, lettuce-like leaves, suggesting that the genus as a whole contains real food potential. For practical foraging, dayflowers in the Southwest are better understood as potential rather than confirmed food plants, with birdbill dayflower being the more promising species and whitemouth dayflower remaining largely unverified for safe edible use.
Physical Characteristics

Commelina erecta is a PERENNIAL growing to 0.5 m (1ft 8in).
See above for USDA hardiness. It is hardy to UK zone 5. It is in flower from July to September, and the seeds ripen from August to October. The species is hermaphrodite (has both male and female organs).
Suitable for: light (sandy) and medium (loamy) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers dry or moist soil.
UK Hardiness Map
US Hardiness Map
Synonyms
C. hirtella.
Plant Habitats
Woodland Garden Sunny Edge; Dappled Shade; Cultivated Beds;
Edible Uses
Edible Parts: Root
Edible Uses:
Whitemouth dayflower: Not recommended as a food plant due to lack of confirmation [2-3]. Birdbill dayflower (comparative reference): Roots excellent, leaves edible but sparse; high potential but limited documentation. This genus illustrates a key foraging principle: never assume edibility across a genus—species identity matters. Edible Uses & Rating: Whitemouth dayflower has no reliable documentation of edible use for leaves, flowers, or stems, and only the roots are occasionally mentioned as potentially edible. Because of this lack of confirmation, it should not be treated as a food plant. Birdbill dayflower, however, is a different case. Its roots are edible and of very high quality, and its leaves are mild and lettuce-like. This contrast suggests that edibility within the genus varies by species and that species-level identification is essential. Overall rating for whitemouth dayflower as a food plant: low / uncertain. Overall rating for birdbill dayflower (comparative reference): high potential (roots especially) [2-3]. Taste, Processing & Kitchen Notes: Whitemouth dayflower has no established culinary tradition, and taste data are not available in a reliable form. Birdbill dayflower roots, by contrast, are described as mild, potato-like, and versatile. They can be eaten raw or cooked and perform well in soups, boiling, baking, frying, and steaming, producing a sweet, hearty broth when simmered. Leaves of birdbill dayflower are mild, tender, and lettuce-like, though sparse in quantity, making them impractical for large harvests. This contrast highlights an important foraging principle: genus-level similarity does not guarantee species-level edibility [2-3]. Seasonality (Phenology): Whitemouth dayflower typically blooms from late spring through summer, roughly May to September, depending on location and rainfall patterns. Birdbill dayflower in the Southwest blooms mainly during the summer monsoon season, from July to October. Roots can theoretically be harvested year-round, but aboveground growth is usually needed to locate the plants. Safety & Cautions (Food Use): Whitemouth dayflower should not be treated as an edible plant due to a lack of reliable documentation. Do not generalize edibility from eastern Commelina species or from birdbill dayflower to whitemouth dayflower. Species-level identification is essential. Birdbill dayflower roots appear safe based on field testing and related species, but documentation is limited, so cautious, minimal testing is always advised [2-3]. Harvest & Processing Workflow: For whitemouth dayflower, no harvest workflow is recommended for food use. For birdbill dayflower (comparative reference), roots are located by identifying aboveground plants during the growing season, gently excavating clustered tuberous roots, leaving some behind for regeneration, and processing like small potatoes. Cultivar/Selection Notes: There are no food cultivars of whitemouth dayflower. Related species in Mexico and Central America are sometimes treated collectively, reflecting their similar root structures and uses, but this has not translated into formal agricultural selection in North America. Look-Alikes & Confusion Risks: Dayflowers can be confused with spiderworts (Tradescantia), but dayflowers are distinguished by hairless filaments and the presence of a large folded spathe (bird’s-bill-like bract). Within Commelina, correct species identification is critical because edibility varies significantly. Traditional / Indigenous Use Summary: Whitemouth dayflower does not have strong ethnobotanical documentation as a food plant. In contrast, related species in Mexico and the Southwest region show food use of roots, and birdbill dayflower appears to have real edible potential, though documentation remains sparse. This pattern suggests localized traditional knowledge rather than widespread cultural use. Root[105, 177]. Fleshy[43].
References More on Edible Uses
Medicinal Uses
Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.
None known
References More on Medicinal Uses
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Other Uses
Dayflowers are sometimes grown ornamentally for their bright blue flowers. Dayflowers provide nectar and pollen for insects and contribute to warm-season floral diversity. Their low, soft growth provides microhabitat for insects and small invertebrates. In natural systems, they function more as ecological background species than dominant plants.
Special Uses
Food Forest
References More on Other Uses
Cultivation details
Whitemouth dayflower is best understood as a botanically interesting but nutritionally uncertain species. It belongs to a genus that includes excellent food plants, but it itself lacks reliable edible documentation. For foragers, it is more valuable as a learning species for identification and genus recognition than as a food source. Birdbill dayflower, however, stands out as a genuinely promising edible relative, especially for its roots. Growing Conditions: Whitemouth dayflower favors grasslands, open woodlands, and seasonally moist sites, often appearing in disturbed soils, field margins, and open habitats. It tolerates heat well and grows during warm months, behaving as a summer-active perennial. Birdbill dayflower prefers montane grasslands and woodland edges in southern Arizona and New Mexico, especially in areas influenced by summer rains. Habitat & Range: Whitemouth dayflower ranges from the southeastern United States westward into southeastern Arizona and northward into the central plains and mid-Atlantic regions. It is more common outside the core Southwest. Birdbill dayflower is primarily restricted to Arizona and New Mexico, occurring in mountain grasslands and woodlands. Size & Landscape Performance: Whitemouth dayflower is a small to medium herbaceous perennial that does not form dense groundcover. It persists through underground root systems and reappears seasonally. It is not aggressive or invasive in most natural systems. Cultivation (Horticulture): Dayflowers are sometimes grown ornamentally for their bright blue flowers, but whitemouth dayflower is not cultivated as a food plant. Birdbill dayflower and related tropical species (such as tuberous dayflower in Mexico) show that the genus has horticultural and food potential, but this has not been developed for North American cultivation. Pests & Problems: Some sources warn of saponins in roots and oxalates in leaves for certain Commelina species, though field sampling of birdbill dayflower did not show noticeable adverse effects. In general, insect damage and fungal issues can affect flowers and leaves, especially in humid conditions. Pollination: Flowers are insect-pollinated, with their bright blue petals attracting bees and other pollinators. The spathe structure protects developing flowers and seeds. Identification & Habit: Whitemouth dayflower is a perennial, joint-stemmed plant with a soft, grass-like appearance and leaves that resemble narrow lily or grass blades. The stems are segmented at the nodes, and the leaves sheath the stem at their bases. The plant produces distinctive, irregular blue flowers that emerge from a large, folded, leaf-like bract called a spathe (often described as a “bird’s bill”). This spathe is one of the easiest identification features of the genus Commelina. In whitemouth dayflower specifically, the spathe margins are fused at the base, and the flowers are tri-petaled with two blue petals and one smaller white petal, giving the plant its common name. The overall form is upright to loosely spreading, and plants often occur in scattered patches rather than dense colonies. Birdbill dayflower, the southwestern relative, has a similar growth form but differs in flower structure and spathe shape, and—critically for foragers—produces small, clustered, tuber-like roots. Prefers a light well-drained loam with added leafmold[1, 42]. Succeeds in an ordinary, reasonably moist soil in a sunny position with some shelter[164]. A polymorphic plant[200]. This species is not very winter hardy, the roots are best dug up in autumn and stored like dahlias in a cool frost free place and then planted out in spring[200]. When grown in a light well-drained soil and mulched well, the roots usually survive the winter outdoors[1]. For polyculture design as well as the above-ground architecture (form - tree, shrub etc. and size shown above) information on the habit and root pattern is also useful and given here if available. The plant growth habit is a clumper with limited spread [1-2]. The root pattern is rhizomatous with underground stems sending roots and shoots along their length [1-2].
References Carbon Farming Information and Carbon Sequestration Information
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Plant Propagation
Seed - sow March in a greenhouse. The seed usually germinates in 4 - 5 weeks at 20°c[164]. When they are large enough to handle, prick the seedlings out into individual pots plant them out in late spring or early summer, after the last expected frosts. Division in early spring. Make sure that each portion has at least one growing bud[111, K]. Cuttings during the growing season. Very easy[200].
Other Names
If available other names are mentioned here
Whitemouth dayflower, dayflower, wild dayflower.
Native Range
NORTHERN AMERICA: United States, Indiana, New Jersey, New York, Pennsylvania, West Virginia, Iowa, Nebraska, Oklahoma, Florida, Georgia, Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Virginia, Texas, Arizona, Mexico, Tamaulipas, Chiapas, Jalisco, Yucatán, SOUTHERN AMERICA: Belize, Costa Rica, Guatemala, Honduras, Nicaragua, Panama, El Salvador, Colombia, Ecuador, Peru,
Weed Potential
Right plant wrong place. We are currently updating this section.
Please note that a plant may be invasive in one area but may not in your area so it's worth checking.
Whitemouth dayflower can behave as a minor weed in disturbed sites and grasslands but is not aggressively invasive. It is more persistent than aggressive.
Conservation Status
IUCN Red List of Threatened Plants Status : Least Concern.
Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.
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