Moss Rose (Portulaca)

Portulaca grandiflora, universally known as the Moss Rose, is a brilliantly colored, low-growing trailing annual belonging to the Portulacaceae family. Native to the hot, arid plains of Argentina, southern Brazil, and Uruguay, it is renowned globally as the ultimate survivalist plant for the summer garden. It thrives in environments where almost all other ornamental flowers would wither and die: intense, searing heat, prolonged drought, and poor, rocky soil.

Identification is defined by its unique succulent nature. The plant forms a dense, sprawling mat of reddish, creeping stems covered in fleshy, needle-like, cylindrical green leaves designed to store water. The flowers are stunning, resembling miniature, ruffled wild roses with fragile, crepe-paper-like petals. They bloom in a blindingly bright neon spectrum of magenta, yellow, orange, pink, and white. A fascinating quirk of Portulaca is that the flowers are phototropic—they open fully only in bright, direct sunlight and tightly close their petals at night or on cloudy days.

The floral formula is ⊕ ⚥ K2 C5 A∞ G(3-8). It features a radially symmetrical, bisexual flower. It has only 2 sepals (a defining characteristic of the Portulacaceae family), typically 5 petals (though double varieties have many more), numerous stamens, and a semi-inferior ovary composed of 3 to 8 fused carpels that eventually forms a small capsule packed with tiny, iridescent seeds.

Growing Portulaca requires almost complete neglect. It demands absolutely full, baking sun. It must be planted in sandy, highly porous, well-draining soil; rich, heavy, soggy soil will instantly cause fatal root and stem rot. Once established, it requires very little watering, surviving entirely on the water stored in its succulent leaves. It is perfect for hot concrete planters, rock gardens, and trailing out of hanging baskets.

Culturally, it is prized as a low-maintenance, high-impact landscape groundcover. In many tropical regions, it easily self-seeds and acts as a short-lived perennial.

WARNING: Portulaca is TOXIC to pets. The fleshy leaves and stems contain high levels of soluble calcium oxalates. If a dog, cat, or horse ingests the plant, it can cause severe drooling, tremors, and kidney failure in large amounts. Keep trailing hanging baskets out of reach of curious pets.

It is sometimes confused with Ice Plants (Delosperma), which share a similar succulent trailing habit and neon flowers but belong to a different family and have angular, not cylindrical, leaves. Contrast this intense sun-lover with the shade-loving Balsam or explore more groundcovers in the Flower Identifier.