Chamaesyce maculata (L.) Small
Chamaesyce mathewsii Small
Chamaesyce supina (Raf.) H. Hara
Chamaesyce tracyi Small
Euphorbia maculata L.
Euphorbia supina Raf.
Prostrate Spurge, Spotted Sandmat, Spotted Spurge, Milk Purslane
These North American native plants are common weeds, found on roadsides, gravelly areas, atop mulch, and in other disturbed soils.
Identification: This common species apparently takes on multiple forms, judging from the surprisingly variable descriptions I have found so far. Some sources say it keeps a low profile, about 1" (2.5 cm) high, lying flat on the ground, hence the “prostrate” and “sandmat” in two of its common names. This is the only form I have so far noticed. Newcomb’s Wildflower Guide says it is “more or less erect with a stem up to 30" (76 cm) high.” The article at missouriplants.com describes it as up to 12" (30 cm) in height, “erect to ascending or reclining.” Wild Urban Plants of the Northeast describes it as 1¾-4" (5-10 cm) tall. Wildflowers in the Field and Forest says it is 4-36" (10-91 cm) in height.
Stems are green, often pale to strong red in sunlight, heavily branched, with sparse tomentoulose hairs. They produce a milky latex when cut. The leaves are also variable. They are opposite, oval to linear and somewhat asymmetric, with one edge flatter than the other and fine serrations, ⅛-1" (5-30 mm) long and about one third to one half as wide. Leaves often have an irregular dark reddish blotch near the center. Flowers are practically invisible at less than ⅛" (3.2 mm) in size. They are cyathia with four “petals” that are white or light pink. Fruits are about ¹/₃₂" (1 mm) in size.
Edibility: Poisonous The milky sap may cause a mild contact dermatitis. Gloves are advisable when handling this plant.
This species is similar to several others, some shown below:
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|Plant||Sometimes prostrate, only 1" (2.5 cm) high; sometimes up to 3' (91 cm) in height. Stems are green or pale to strong red in sunlight, heavily branched, with sparse tomentoulose hairs. They produce a milky latex when cut.||Sometimes prostrate, less than 1" (2.5 cm) high; or up to 16" (40 cm) high. Stems vary from green to reddish to dark red, and exude a milky sap when broken. They are hairy, with hairs that point out rather than being matted, ~¹/₃₂" (0.5-1.5 mm) long.|
|Flowers||Less than ⅛" (3.2 mm) in size. They are cyathia with four “petals” that are white or light pink.||Nearly imperceptible at less than ⅛" (3.2 mm) in size. They are cyathia with four “petals” that are white or light pink, appearing from July to October.|
|Leaves||Opposite, oval but somewhat asymmetric, with one edge flatter than the other and fine serrations, ⅛-1" (5-30 mm) long and about one third to one half as wide. Leaves often have a dark reddish blotch near the center.||Opposite, somewhat asymmetric, oval, ¼-¾" (6.3-19 mm) long and one half to two thirds as wide, with widely spaced serrations, often with an irregular dark reddish blotch in the middle.|
|Fruit||¹/₃₂" (1 mm) in size. Hairy.||¹/₃₂-¹/₁₆" (1.5-2 mm) in size, hairless, with three lobes.|
|Habitats||Disturbed soils, roadsides, gravelly areas, atop mulch, gardens, cracks in sidewalks||Meadows, fields, roadsides, disturbed soils|
Chamaesyce maculata on missouriplants.com
Chamaesyce maculata on luirig.altervista.org
Chamaesyce maculata at Illinois Wildflowers
Chamaesyce maculata and C. prostrata at North Carolina State University's Mycological Herbarium
Chamaesyce maculata on Delaware Wildflowers
Chamaesyce maculata on the New England Wildflower Society’s GoBotany site
Chamaesyce maculata at the Lady Bird Johnson Wildflower Center
Hains, Arthur; Farnsworth, Elizabeth & Morrison, Gordon (illus.), Flora Novae Angliae: a Manual for the Identification of Native and Naturalizaed Higher Vascular Plants of New England, Yale University Press, 2011, p. 568
Newcomb, Lawrence, Morrison, Gordon (Illus.), Newcomb’s Wildflower Guide, Little, Brown and Company, 1977, p. 432
del Tredici, Peter, Wild Urban Plants of the Northeast: a Field Guide, Comstock Publishing Associates, a division of Cornell Universty Press, 2010, p. 212
Clemants, Steven; Gracie, Carol, Wildflowers in the Field and Forest, Oxford University Press, 2006, p. 344
Chamaesyce maculata description by Thomas H. Kent, last updated 12 Oct 2018.