Spurge, belonging to the genus Euphorbia, is a large and diverse group of flowering plants within the family Euphorbiaceae, with over 2,000 species worldwide. The genus includes everything from small, low-growing annual weeds found in lawns to large, tree-like succulents cultivated as ornamentals. This variety makes visual identification challenging, yet all species share a few distinctive biological traits necessary for accurate identification.
General Physical Characteristics
The overall form of Spurge plants ranges dramatically, often categorized by growth habit into prostrate, herbaceous, or succulent forms. Many frequently encountered species are low-growing, forming dense, spreading mats across the ground surface. These types typically radiate outward from a central taproot. Stems in the weed-like species are often slender and may display a reddish or purplish hue near the base. The leaves are generally simple and their arrangement varies by species. Leaves can be either opposite (growing directly across from each other) or alternate (staggered along the stem). They are generally small and oval to oblong in shape, sometimes appearing pale green or bluish-green.
Key Identifying Features
The most definitive characteristic shared across nearly all Spurge species is the presence of a milky, white latex sap. This viscous fluid immediately oozes out when any part of the plant is broken or damaged. The sap contains latex and can be an irritant to skin and eyes, functioning as a defense mechanism.
Another unique marker is the plant’s specialized flowering structure, known as a cyathium. A cyathium is not a true flower but an inconspicuous, cup-shaped cluster of greatly reduced male and female flowers. This structure is often surrounded by showy, leaf-like structures called bracts, which are commonly mistaken for petals and can be white, yellow, or greenish-yellow. Following pollination, the fruit develops into a small, three-lobed capsule that often splits open to disperse the seeds.
Common Varieties and Their Appearance
Among the most common species is Spotted Spurge (Euphorbia maculata), recognized by its prostrate, mat-forming growth and small, oval leaves. The stems are typically reddish and hairy. The dark green leaves frequently feature a distinctive maroon or purplish spot in the center of the blade. Its stems do not typically root where they touch the soil.
Prostrate Spurge (Euphorbia prostrata) is a close relative that also forms a flat, spreading mat with reddish stems. The primary visual difference is that its leaves are generally smaller and lack the dark central spot characteristic of Spotted Spurge. Leafy Spurge (Euphorbia esula) looks markedly different; it is a perennial that grows upright, reaching heights of up to three feet. Its leaves are long, narrow, and lance-shaped, and it produces clusters of bright, yellow-green bracts, contrasting sharply with the low-growing annual weeds.
Habitat and Growth Patterns
Spurge is a highly adaptable genus, but the common weedy types tend to thrive in dry, nutrient-poor, and compacted soils. They are frequently found in disturbed areas, such as sidewalk cracks, gravel driveways, thin lawns, and garden beds.
Many weedy species, like Spotted Spurge, are summer annuals, meaning they germinate in warm soil during the spring and summer and complete their life cycle by fall frost. These annuals grow rapidly, forming dense mats and producing numerous seeds throughout the season. Other species, such as Leafy Spurge, are deep-rooted perennials that establish extensive root systems, making them difficult to remove and allowing them to aggressively spread and return year after year.