Spotted spurge: A common weed of container production in nurseries and greenhouses
Euphorbia
maculata (or Chamaesyce maculata) also known as spotted spurge or
spotted sandmat, is a common broadleaf weed in container production in
nurseries and greenhouses. It is an herbaceous, summer annual, low-growing,
weed in the plant family Euphorbiaceae, having spotted leaves. It has small (less than 0.5 inches
long) linear or egg-shaped leaves arranged in opposite pairs. It has a
prostrate growth habit with stems growing up to 2 feet and not more than a few
inches high. There is often a dark spot in the center of leaf. Individual
plants tend to form a mat, along the soil surface, with branches growing
outwards from a central growth point in roughly radial patterns.
Spotted spurge has reddish-colored
branched stems that have fine hairs (Fig 1). Broken or punctured stems secrete
a milky-white, sticky sap that is poisonous and can irritate skin and eyes.
Leaves have a short petiole, are arranged in opposite pairs, and are unequal. Leaves
are small, oblong, dark green with purple spots in the center (on more than 95%
of leaves), hairy, smooth, or finely toothed, mostly rounded at tips, and
measure about one inch. Under ideal conditions, plants begin to flower just one
month after germination. Plants are monoecious, producing tiny, white, and pink
flowers in the leaf axils. Flowers consist of only stamens and hairy pistils,
having white to pink petaloid (Petal like) appendages, and are grouped in
cup-like structures, known as cyathia. The flowers may start producing fruits
and seeds one month after flowering under ideal conditions. Reproduction of
spotted spurge occurs via seeds. Under ideal conditions, plants can produce
seeds prolifically with approximately 500 seeds per square foot. Generally,
plants produce thousands of seeds that may germinate immediately (for seeds
produced in summer) or remain dormant in the soil during winter in order to give
rise to plants in the following spring or summer (for seeds produced in late
summer or fall). Seeds buried deeper
than ½ inch do not germinate due to the absence of light.
Debalina Saha
Assistant Professor, Michigan State UniversityDebalina Saha is an Assistant Professor of ornamental weed management in the Department of Horticulture at Michigan State University. She has an appointment in research, teaching, and extension. Debalina provides statewide weed identification and management recommendations for ornamental plant production in greenhouses, nurseries, landscapes, and Christmas tree production. The primary goal of her research program is to improve upon current weed control practices and develop new effective methods of weed control using an integrated approach that involves both chemical and non-chemical strategies.