18. Eryngium L. (eryngo) (Mathias and Constance, 1941b)
Plants annual or
perennial. Stems erect, ascending, or prostrate. Leaves alternate (sometimes
also basal) or opposite to whorled, the sheathing bases relatively short, not
inflated. Leaf blades simple, entire or palmately lobed, the margins entire or
toothed, the teeth sometimes spiny. Inflorescences terminal or axillary, dense
cylindrical or globose heads of numerous flowers, these solitary or in small
panicles, short- to long-stalked. Involucre subtending each head of 4–10
bracts. Flowers each subtended by a bractlet. Sepals ovate or oblong, entire or
with deep, narrow, spiny teeth or lobes at the tip. Petals rounded at the tip,
white, purple, or blue. Ovaries with small scales or tubercles. Fruits oblong,
obovate, or nearly circular in outline, usually slightly flattened laterally,
brown, each mericarp with 5 angles, lacking ribs, variously with small scales
or tubercles. About 250 species, nearly worldwide.