Dieteria canescens

(Pursh) Nuttall

Trans. Amer. Philos. Soc., n. s. 7: 300. 1840

Common names: Hoary-aster
Synonyms: Machaeranthera canescens (Pursh) A. Gray
Basionyms: Aster canescens Pursh
Treatment appears in FNA Volume 20. Treatment on page 398. Mentioned on page 396.
Annuals, biennials, or short-lived perennials, (subshrubs in var. ziegleri). Stems, branches, and peduncles glabrous, puberulent, or canescent, sometimes also stipitate-glandular or gland-dotted. Leaf blades linear-lanceolate to linear or linear-oblanceolate (ovate to obovate in var. leucanthemifolia), mid 10–60 × 1.5–6(–8) mm, margins entire to irregularly dentate or serrate, faces glabrous, puberulent, or canescent, sometimes sparsely stipitate-glandular; distal bases not clasping or slightly clasping (clasping in var. leucanthemifolia). Involucres campanulate or turbinate. Phyllaries in 3–10 series, appressed, spreading, or reflexed, indurate bases usually glabrous, apices acute to acuminate, 1–3 mm, herbaceous, faces glabrous (indurate bases, sometimes foliaceous parts) or hairy (only foliaceous parts), sometimes stipitate-glandular. Receptacles 2.5–5 mm diam. Ray florets pistillate and fertile, or sterile or 0 (in var. shastensis); laminae white, blue, or purple, 6–12 × 1–3 mm. Disc florets: corollas 4–6(–7) mm. Cypselae glabrous or moderately appressed-hairy.

Distribution

V20-909-distribution-map.gif

w North America, nw Mexico.

Discussion

Varieties 10 (10 in the flora).

References

None.

Key

1 Phyllaries usually appressed, sometimes spreading, rarely reflexed > 2
1 Phyllaries spreading to reflexed, rarely appressed > 5
2 Ray florets sterile or 0 Dieteria canescens var. shastensis
2 Ray florets pistillate and fertile > 3
3 Phyllaries densely appressed-hairy, usually eglandular, sometimes sparsely stipitate-glandular, then obscured by appressed hairs Dieteria canescens var. ambigua
3 Phyllaries glabrous or stipitate-glandular, rarely appressed-hairy or canescent > 4
4 Stems stipitate-glandular, sometimes also canescent, rarely glabrous Dieteria canescens var. aristata
4 Stems glabrous, puberulent, or canescent, sometimes sparsely stipitate-glandular Dieteria canescens var. glabra
5 Involucres (9–)10–16 mm > 6
5 Involucres 6–10(–12) mm > 7
6 Subshrubs; involucres (10–)12–16 mm; phyllary apices densely stipitate-glandular Dieteria canescens var. ziegleri
6 Biennials or short-lived perennials; involucres (9–)10–15 mm; phyllary apices densely appressed-hairy, sometimes stipitate-glandular, then obscured by hairs Dieteria canescens var. nebraskana
7 Stems canescent, sometimes sparsely stipitate-glandular > 8
7 Stems stipitate-glandular, usually also puberulent or canescent, sometimes glabrous > 10
8 Stem usually 1, stiffly erect, branches widely divaricate, straight, stiff Dieteria canescens var. incana
8 Stems 1+, usually ascending, branches loosely spreading to ascending, not widely divaricate, curved, flexible > 9
9 Phyllaries in 5–10 series; ray florets pistillate and fertile Dieteria canescens var. canescens
9 Phyllaries in 3–5(–7) series; ray florets sterile or 0 Dieteria canescens var. shastensis
10 Stems canescent, usually gland-dotted; most peduncles 0 (heads sessile) or shorter than involucres Dieteria canescens var. sessiliflora
10 Stems stipitate-glandular, also sometimes puberulent or canescent; peduncles equaling or longer than involucres > 11
11 Mid and distal leaf blades ovate, oblong, or obovate, lengths 1.5–4 times widths Dieteria canescens var. leucanthemifolia
11 Mid and distal leaf blades linear-lanceolate to linear, lengths 4+ times widths Dieteria canescens var. aristata