Whiteweed flower floret pistils. Coloured scanning electron micrograph (SEM) of the pistils (red, the female reproductive organs) emerging from the true flowers or florets (yellow) of a whiteweed plant. The whiteweed plant (Ageratum sp.) is a member of the Asteraceae family of flowering plants, and so its flower head (capitula) consists of numerous florets. Ageratum flowers only have these tubular florets, and do not have the disc florets (petal- like structures) found in daisies, the best-known member of Asteraceae. Whiteweed flowers are widely grown as ornamental garden plants. Magnification unknown.