2. Heterotheca canescens (DC.) Shinners

Chrysopsis villosa (Pursh) Nutt. ex DC. var. canescens (DC.) A. Gray

C. canescens (DC.) Torr. & A. Gray

Pl. 236 c–e; Map 987

Plants perennial herbs, often with taproots and usually also rhizomes, the rootstock often somewhat woody. Stems 15–60 cm long, relatively slender, moderately to densely pubescent with appressed or curved, silvery hairs, not glandular. Stem leaves 1–3 cm long, linear to narrowly oblanceolate or oblanceolate, mostly short-tapered to a sharply pointed tip, the margins entire and hairy, the surfaces appearing gray, not roughened, densely pubescent with appressed or less commonly also curled, silvery hairs, these all or nearly all lacking an expanded, bulbous base, not glandular. Involucre 5–7 mm long, the bracts in 4–6 unequal, overlapping series, narrowly triangular-lanceolate to nearly linear, often purplish-tinged at the tip, the green central stripe often difficult to observe, hidden by the relatively dense, appressed, silvery hairs, not glandular. Ray florets 10–22, the corollas 4–10 mm long. Disc florets 15–45, the corollas 4.5–6.5 mm long, often sparsely and minutely hairy on the outer surface toward the tip. Pappus of the ray and disc florets similar, consisting of an outer series of relatively few bristlelike scales 0.2–0.5 mm long and an inner series of 25–40 bristles 5.0–7.5 mm long. Fruits of the ray and disc florets similar, 1.2–3.0 mm long, somewhat flattened, 3- or 4-nerved on each face, the surface moderately hairy. 2n=18, 36. August–October.

Uncommon, known only from historical collections from Holt County (Missouri, Kansas, Oklahoma, Texas, and New Mexico). Loess hill prairies.

The Missouri occurrence of this species is unusual. Not only does it represent an eastern disjunction from the main range of the species in the southern Great Plains, but H. canescens has not been reported from elsewhere in the loess hills along the Missouri River or from hill prairies (Semple, 1996). This might lead the reader to believe that the taxon is nonnative in the state, but the brief labels on the more than ample series of specimens examined by Steyermark (1963) and later botanists seem to indicate that it was part of the natural landscape when it was first discovered there by John Kellogg and B. F. Bush in 1931. The species has not been rediscovered in Missouri since that time and has probably become extirpated from the state.

Steyermark (1963) reported Chrysopsis villosa var. angustifolia (Rydb.) Cronquist as a member of the Missouri flora and cited a single historical specimen accessioned in the herbarium of the New York Botanical Garden from Greene County (Springfield, July 1905, P.C. Standley s.n.). He apparently did not personally examine the specimen, stating that the report was based on information provided to him by William J. Dress, who was completing a doctoral dissertation on the group (Dress, 1954). Vernon L. Harms (1963, 1968), who also completed doctoral studies on the group, transferred the taxon into Heterotheca (H. villosa (Pursh) Shinners var. angustifolia (Rydb.) V.L. Harms) but did not cite the specimen or include Missouri in the range of this mostly Great Plains species. Following the systematic studies of John C. Semple (1996), the taxon currently is known as H. stenophylla (A. Gray) Shinners var. angustifolia (Rydb.) Semple, but Semple also did not include Missouri in its range. Attempts to locate the original voucher specimen during the present work were unsuccessful, leading to the conclusion that this specimen either was miscited by Dress or misdetermined. H. stenophylla var. angustifolia is similar to H. canescens, but it differs in its somewhat larger leaves with less dense, more spreading hairs and heads with slightly larger involucres, among other characters (Pl. 236 i–k). It is not very likely to be found in southwestern Missouri.