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FNA | Family List | FNA Vol. 20 | Asteraceae | Dieteria

3. Dieteria canescens (Pursh) Nuttall, Trans. Amer. Philos. Soc., n. s. 7: 300. 1840.


Aster canescens Pursh, Fl. Amer. Sept. 2: 547. 1813; Machaeranthera canescens (Pursh) A. Gray

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.

Varieties 10 (10 in the flora): w North America, nw Mexico.

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


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