Portulaca is the name of a genus of flowering plants. There are many varieties of portulaca and most are hardy to USDA zones 7 to 11. Generally found wherever conditions are hot and dry, portulaca are planted for their colorful flowers in rock gardens or in masses, as ground cover. Some portulacas have a milky sap that may cause dermatitis in sensitive individuals.
Commonly known as purslane, this portulaca variety grows 3 to 10 inches in height, and loves the heat and direct sunlight. Yellow flowers appear in July and, if you don't snip them off before they produce seed, you can end up with lots of baby purslane. Each plant can produce over 200,000 seeds, according to the University of California at Davis. While many gardeners consider purslane a weed, others like eating it. If you want to grow it to enjoy its flowers, consider the 'Yubi Summer Joy Scarlet' variety.
Portulaca grandiflora is commonly known as moss rose and is the main species sold in gardening centers. This variety of portulaca is another sun-lover that hails from Brazil. A tender annual, the moss rose will grow to 6 inches in height. It thrives in dry soil. Generally used as ground cover in the residential landscape, it also looks pretty trailing over the sides of a hanging basket. Moss rose flowers in white, yellow, pink, orange and red.
Portulaca umbraticola, or wingpod purslane, is a summer annual that grows to 2 inches in height. Native to the Sonoran desert, wingpod purslane blooms in tiny yellow flowers with red tips. This is a low-maintenance plant that will do well in a xeriscape situation. It will also attract bees and butterflies into the summer garden. Wingpod purslane is hardy to USDA zones 7b to 11.