Why these fleeting blue flowers are named after a pair of Dutch botanists

Gardening · Published 3 October 2026 Swipe more like this →

In short: Known as dayflowers for their remarkably short-lived blooms, the Commelina genus is a botanical puzzle of asymmetry. Named by Carl Linnaeus to honor two Dutch botanists, these plants hide their reproductive secrets within specialized, fluid-filled structures called spathes, offering a masterclass in complex, highly adapted floral architecture.

The genus Commelina, the largest in the Commelinaceae family, comprises approximately 208 species. These herbs, which can be annual or perennial, are defined by their strongly zygomorphic flowers—meaning they possess only one plane of symmetry. This asymmetry is reflected in their petals: the two upper petals are typically larger and clawed, while the lower petal is reduced and often distinct in color. The 18th-century Swedish taxonomist Carl Linnaeus named the genus after Jan Commelijn and his nephew Caspar, intending for the two showy petals of Commelina communis to represent the two men.

Beyond their striking blue, lilac, or yellow petals, these plants are distinguished by their unique reproductive mechanics. Each flower stalk is protected by an involucral bract known as a spathe, which is often filled with a mucilaginous liquid. Inside, the plant houses one or two scorpioid cymes. The upper cyme is often vestigial or bears only male flowers, while the lower cyme is multi-flowered. This arrangement ensures that the plant maximizes its reproductive potential despite the ephemeral nature of the individual blooms, which have earned the genus the nickname 'widow's tears.'

While some species like Commelina communis are considered common weeds in North America and Europe, others serve as vital resources. In parts of Southeast Asia and Africa, species such as Commelina benghalensis are consumed as leaf vegetables. The genus exhibits significant diversity in root structure, ranging from fibrous to tuberous, as seen in the perennial Commelina tuberosa. Whether growing in the wild or cultivated for their vivid color, these plants remain a fascinating subject for botanists, who continue to debate the precise classification and typification of various species within the group.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• Why the spiderwort and water hyacinth share a surprising botanical family tree
• The botanical family that conquered the world's temperate gardens
• DNA studies swelled the primrose family to nearly 2,800 species
• Why the Primula is the ultimate herald of the spring garden
• The accidental fruit: how a French missionary’s garden gave us the clementine
• Poison hemlock is a lethal, invasive weed that hides in plain sight among us.
• The citron is the ancient, fragrant ancestor of almost every citrus fruit you eat.
• The Morning Glory Family: From Garden Beauties to Parasitic Weeds and Psychedelic Seeds
• Cider apples are not just fruit; they are complex chemical engines for perfect fermentation.
• Why some apples turn into smooth sauce while others hold their shape perfectly
• The butterfly palm is a Madagascar native that conquered the world's living rooms.
• The filbert is a hazelnut, but not every hazelnut is a true filbert.

More in Plants · More in Gardening · Latest · A–Z · All topics