Coefficient of Conservatism:
Coefficient of Wetness:
CALTROP, PUNCTURE VINE
R. W. Smith
Originally native, apparently, to the Mediterranean area and now a noxious weed in warm climates. Rarely found as far north as Michigan, where it was first collected in 1930 along a roadside at Grand Rapids, Kent Co. It was collected in several other counties 1931–1937, so probably was dispersed before 1930. Still not common, but found also in poor lawns, gardens, parking lots, and such disturbed ground.
Easily recognized by its prostrate habit; hairy stems and leaves, the latter consisting usually of 6–7 pairs of small leaflets; and spiny nutlets, the two principal spines on each nutlet stouter than those of the equally unpleasant Cenchrus.