The Asiatic Dayflower (Commelina communis) is an annual herbaceous plant native to East and Southeast Asia. Historically, it has been used in its native range as both a leafy vegetable and a component in traditional medicine. The plant is now widely distributed globally, having been introduced to regions like Europe and eastern North America, establishing itself in various environments.
Characteristics and Identification
Identifying the Asiatic Dayflower begins with its distinctive, short-lived bloom, which is the source of its common name. Each flower possesses three petals, with the upper two being a striking sky-blue and the lower one being noticeably smaller and white. These flowers emerge from a distinctive, folded green bract called a spathe, and typically open for only a single morning before wilting away by afternoon.
The plant grows with slender, sprawling stems that are often decumbent, creeping along the ground and sometimes rooting at the nodes. Its leaves are lance-shaped to ovate, featuring parallel veins and a sheathing base that clasps the stem. Commelina communis thrives in moist, disturbed habitats, such as forest edges, ditches, and garden beds, where it is often considered a pervasive garden weed.
Culinary Preparation and Uses
Nearly all parts of the young Asiatic Dayflower plant are considered edible, including the leaves, stems, and flowers, offering a versatile culinary green. The young shoots and tender leaves can be consumed raw, providing a mild, fresh, and sometimes slightly sweet or pea-like flavor to salads. The distinctive blue flowers can also be used as a colorful, edible garnish.
Older leaves and stems are generally better suited for cooking due to their texture and a higher concentration of oxalates, which can be reduced by heat. When cooked, the leaves function well as a potherb, similar to spinach, and can be incorporated into stir-fries, soups, or stews. The plant contains a mucilaginous quality, lending a pleasant, slightly thick texture when used in cooked dishes. The seeds, found within small capsules, have even been historically utilized as a famine food.
Traditional Therapeutic Applications
In traditional Asian medicine, the Asiatic Dayflower, known as Yazhicao in China, has been employed for a number of ailments, particularly those related to heat and fluid balance. A primary application is its use as a febrifuge, traditionally administered to reduce fever, and as a diuretic to promote urination and relieve symptoms of edema. The plant has also been historically applied externally, where a poultice was used on skin eruptions, insect bites, and carbuncles.
Internal preparations, often in the form of decoctions or teas, have been used to address symptoms like sore throats, tonsillitis, and internal bleeding. Contemporary research has begun to isolate specific compounds that support these historical applications. For instance, the plant contains flavonoids and polyphenols, which contribute to its recognized antioxidant and anti-inflammatory effects.
Specific compounds support these uses; p-hydroxycinnamic acid demonstrates antibacterial properties, and D-mannitol is noted for its antitussive (cough-suppressing) effect. Studies also suggest the plant may help manage blood sugar by inhibiting alpha-glucosidase, an enzyme involved in carbohydrate digestion. Furthermore, extracts have shown the ability to modulate the NF-κB signaling pathway, pointing to a mechanism for its anti-inflammatory action.
Safety and Responsible Foraging
Correct identification is paramount when foraging, as the Asiatic Dayflower can be confused with other species, such as the native Virginia Dayflower (Commelina virginica). Foragers should focus on harvesting only younger leaves and shoots, as older foliage contains higher levels of oxalates. Cooking older parts, such as boiling or blanching, helps mitigate this digestive concern.
Environmental contamination poses a significant risk because this plant can bioaccumulate metals like copper, zinc, and lead. Never harvest the plant from roadsides, industrial areas, or sites where pesticides, herbicides, or heavy metal run-off are likely. Sustainable harvesting involves only taking what is needed, ensuring sufficient plants remain to reproduce and maintain the local population.