Asteraceae >
Flowers grouped into heads Asteraceae
Involucral bracts of the female heads or of the outer florets enclosing the fruit(s) at maturity and forming a burr (Fig. 42)
Burrs without hooked appendages, each burr containing 1 fruit (Fig. 41) Ambrosia
Fruiting head without spines but with teeth, hairy. Perennials
Leaves 2–4-pinnate, linear to oblong, mostly up to 10 cm long. Perennial herb with long suckering roots. Widespread. Weed of roadsides and waste places. Introd. from America. Fl. spring–summer Ambrosia tenuifolia