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

170. Erigeron strigosus Muhlenberg ex Willdenow, Sp. Pl. 3: 1956. 1803.

Common eastern fleabane, vergerette rude

Erigeron annuus (Linnaeus) Persoon subsp. strigosus (Muhlenberg ex Willdenow) Wagenitz

Annuals, biennials, or short-lived perennials, 30–70 cm; fibrous-rooted, caudices simple, sometimes lignescent, sometimes producing rhizomes that bear leaf tufts at upturned ends. Stems erect or ascending, sparsely to moderately strigose to strigillose or hirsuto-strigillose (hairs usually ascending, rarely spreading, 0.1–1.2 mm), eglandular. Leaves basal (usually persistent through flowering) and cauline; basal blades spatulate to broadly or narrowly oblanceolate to linear, (10–)30–150(–170) × 5–15(–21) mm, cauline usually gradually reduced distally, continuing to near heads, margins entire or shallowly to deeply serrate or crenate, faces glabrous or glabrate to sparsely strigose or strigoso-hirsute, eglandular. Heads 10–200+ in loosely corymbiform to paniculiform-corymbiform arrays (on distal branches). Involucres (2–)3–4 × 5–12 mm. Phyllaries in 2–4 series, glabrous, strigose, or sparsely hirsute, sometimes minutely glandular. Ray florets 50–100; corollas white, less commonly pinkish or bluish, 4–6 mm, laminae coiling. Disc corollas 1.5–2.5 mm (throats sometimes slightly indurate and inflated). Cypselae (0.5–)0.9–1.2 mm, 2-nerved, faces sparsely strigose; pappi: outer crowns of setae or scales, inner 0 (rays) or of 8–15 bristles (disc).

Varieties 4 (4 in the flora): North America; introduced in Europe, Pacific Islands (Hawaii).

1 Phyllary hairs flattened, 0.5–1.2 mm; stem hairs appressed to spreading, 0.5–1 mm   170c Erigeron strigosus var. septentrionalis
+ Phyllary hairs terete, mostly 0.1–0.5 mm; stem hairs appressed to ascending, 0.1–0.4(–0.8) mm   (2)
2 (1) Annual or rarely biennial, without rhizomes; various habitats, often ruderal   170d Erigeron strigosus var. strigosus
+ Plants usually perennial (sometimes killed prematurely by severe drought), with rhizomes that bear overwintering leaf tufts at upturned ends; shallow soils over calcareous rock   (3)
3 (2) Basal leaves linear to linear-oblanceolate, 1–3.5(–6) mm wide; cauline leaf faces sparsely to moderately strigillose   170b Erigeron strigosus var. dolomiticola
+ Basal leaves oblanceolate to narrowly obovate or spatulate, (3.2–)3.8–15(–21) mm wide; cauline leaf faces glabrous, margins and midveins ciliate   170a Erigeron strigosus var. calcicola


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