Plant of the Week
Birdbill Dayflower (Commelina dianthifolia)
By Charlie McDonald
Birdbill dayflower is in the spiderwort family (Commelinaceae), which has about 40 genera and 600 species worldwide, mostly in the tropics. The two most common genera in North America are Commelina (the dayflowers) and Tradescantia (the spiderworts). There are nine species of dayflower in the continental United States, four of which are native and the other five introduced. Whitemouth dayflower (Commelina erecta), climbing dayflower (Commelina diffusa), and Virginia dayflower (Commelina virginica) are common native species found mostly in the eastern half of the United States. Asiatic dayflower (Commelina communis) is a common introduced species found in the eastern half of the United States and the Pacific Northwest. Birdbill dayflower grows in Arizona, New Mexico, southern Colorado, and trans-Pecos Texas.
The flowers of all dayflowers emerge from a folded leaf-like structure called a bract. In birdbill dayflower, the bract has a long tapered tip. The flowers of all dayflowers are blue, often a lovely pastel. Birdbill dayflower has three petals, but several of the very common species have only two. The flowers are open in the morning, but wither by mid-day. Actually, the petals absorb moisture from the atmosphere and turn to mush, a phenomenon called deliquescence.
Birdbill dayflower grows in rocky soils in woodland and forest openings. While many of the dayflowers grow in wet soils, birdbill dayflower grows on relatively dry well drained slopes. Plants thrive with the onset of summer rains.