107. Dittrichia Greuter, Exsicc. Genav. Conserv. Bot. Distrib. Fasc. 4: 71. 1973.
[For Manfred Dittrich, b. 1934, German botanist]
Robert E. Preston
Annuals [perennials], mostly 20–130 cm (glandular, viscid). Leaves mostly cauline (at flowering), alternate; sessile; blade margins entire or dentate [serrate]. Heads radiate, in racemiform or paniculiform arrays. Involucres ± campanulate, 3–8[–10+] mm diam. Phyllaries persistent (spreading to reflexed in fruit), in 3–4 series, unequal. Receptacles flat, smooth or alveolate, epaleate. Ray florets (6–)10–12(–16), pistillate, fertile; corollas yellow, aging reddish, laminae 2–7 mm. Disc florets 8–20+; corollas yellow, aging reddish, lobes 4–5. Cypselae ellipsoid to terete (abruptly constricted distally; usually glandular distally); pappi persistent (fragile), of basally connate, barbellate bristles in 1 series. x = 9, 10.
Species 2 (1 in the flora): introduced; Mediterranean; introduced also in Asia, Africa, Australia.
Dittrichia viscosa (Linnaeus) Greuter [Inula viscosa Linnaeus, Cupularia viscosa (Linnaeus) Godron & Grenier] was collected in the late 1800s as a ballast weed in Florida, New Jersey, and Pennsylvania. It does not appear to have become naturalized at any of those sites (A. Cronquist 1980; J. E. Arriagada 1998).