Milk purslane, scientifically known as Euphorbia maculata, is a common summer annual plant found in gardens, lawns, and disturbed areas. Also known as spotted spurge or spotted sandmat, this low-growing species is often mistaken for common purslane, which is edible. Understanding its distinct characteristics is important for effective garden management.
Identification and Characteristics
Milk purslane typically exhibits a prostrate growth habit, forming dense mats up to 16 inches in diameter, radiating from a central taproot that can extend two feet deep. Its slender stems are often reddish or pink, covered in fine hairs, and branch out from a central point without rooting at the nodes. The small, oval-shaped leaves, 1/8 to 1/2 inch long, grow in opposite pairs and may feature a distinctive dark, often purplish-red or maroon spot in their center, though this spot is not always present.
When broken, the plant exudes a milky white sap, a key identifier for plants in the Euphorbia family. It produces tiny, inconspicuous pinkish or greenish flowers in cup-like structures called cyathia, followed by small, hairy, three-part seed capsules, each containing minute brown to gray seeds, which are distinctly ridged. Milk purslane thrives in full sun and can grow in various soil conditions, including poor, compacted soil, making it common in sidewalk cracks, roadsides, and cultivated areas.
Distinguishing from Common Purslane
Differentiating milk purslane (Euphorbia maculata) from common purslane (Portulaca oleracea) is important because common purslane is edible. A primary distinguishing feature is the sap: milk purslane releases a milky white latex when broken, while common purslane has clear or no obvious sap.
Their leaves also differ significantly. Milk purslane has thinner, flat, oval leaves that often display a central dark spot and may be slightly hairy. Common purslane, in contrast, possesses thick, fleshy, succulent leaves that are entirely green and hairless. Milk purslane stems are typically thinner, reddish, and hairy, while common purslane stems are smooth, round, and more succulent, often reddish-green. Additionally, milk purslane flowers are tiny and inconspicuous, unlike common purslane’s small yellow flowers.
Why It Is a Nuisance
Milk purslane is a problematic weed due to its aggressive growth and prolific seed production. It rapidly forms dense mats that can outcompete and smother desirable plants in lawns, gardens, and landscape beds. A single plant can produce several thousand seeds, and these seeds can germinate quickly, leading to multiple generations within a single growing season. This rapid reproduction allows milk purslane to quickly infest bare spots and weak areas in turf, reducing overall lawn quality.
Its milky white sap is an irritant to skin and eyes upon contact and can cause adverse reactions if ingested. While often mistaken for edible common purslane, milk purslane is toxic and should not be consumed by humans or animals. Its ability to thrive in disturbed sites, including sidewalk cracks and compacted soils, further contributes to its status as a pervasive and unwelcome plant.
Control and Management
Managing milk purslane effectively involves cultural and chemical strategies. For small infestations, hand-pulling is effective, especially when plants are young. When hand-pulling, it is important to remove the entire taproot, which can be quite long, to prevent regrowth. Wearing gloves is advisable to avoid contact with the irritating milky sap.
Cultural practices play a role in prevention. Maintaining a dense, healthy lawn through proper mowing, fertilization, and irrigation helps to crowd out weeds. Applying a layer of mulch, at least 3 inches deep, can suppress seed germination by blocking sunlight. For chemical control, pre-emergent herbicides can be applied in early spring before seeds germinate, typically when soil temperatures rise above 60°F. Post-emergent herbicides designed for broadleaf weeds can be used for existing plants, selecting products that will not harm turfgrass. Always follow label directions for safe and effective application.