1. Pseudognaphalium helleri (Britton) Anderb. (rabbit tobacco)

Gnaphalium helleri Britton

Pl. 294 g, h; Map 1138

Plants usually strongly aromatic when bruised or crushed. Stems 25–75 cm long, sometimes somewhat woolly when young, but not appearing woolly below the inflorescence at maturity, instead moderately to densely glandular-hairy, the stalked glands variously 0.2–1.0 mm long on the same stem. Leaves 1–9 cm long, linear to narrowly lanceolate or narrowly oblong-lanceolate, the upper surface with moderate to dense, minute, stalked glands. August (July–November elsewhere).

Possibly introduced, known from a single historical collection from St. Louis County (southeastern U.S. west to Oklahoma and Texas). Habitat unknown.

Steyermark (1963) overlooked the single specimen from Missouri, and it remained hidden in the Missouri Botanical Garden herbarium under the name Gnaphalium polycephalum Michx. until its rediscovery in 2000 by Guy Nesom of the Botanical Research Institute of Texas. The closest known native populations in central Arkansas, northern Mississippi, and eastern Kentucky and Tennessee are not particularly close to the Missouri record from Allenton. Although it is plausible that the historical St. Louis County collection represents a native occurrence, it seems more likely that the plant originated from a disturbed habitat such as a railroad embankment.