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FNA | Family List | FNA Vol. 19, 20 and 21 | Asteraceae | Pseudognaphalium

8. Pseudognaphalium saxicola (Fassett) H. E. Ballard & Feller, Sida. 21: 777. 2004.

Cliff cudweed

Gnaphalium saxicola Fassett, Rhodora 33: 75. 1931; G. obtusifolium Linnaeus var. saxicola (Fassett) Cronquist; Pseudognaphalium obtusifolium (Linnaeus) Hilliard & B. L. Burtt var. saxicola (Fassett) Kartesz

Annuals, 4–15(–30) cm; tap­rooted. Stems (filiform) persistently tomentose (indument a loose, envelope-like, transparent haze of extremely thin hairs, doubling apparent stem width), not glandular. Leaf blades elliptic-oblanceolate to oblanceolate, 0.5–3 cm × 2–6 mm (largest at midstem), bases not clasping, not decurrent, margins flat, faces concolor, green, thinly arachnoid-tomentose to glabrate, not glandular (veiny reticulum evident). Heads (2–4) in terminal, capitate clusters (usually immediately subtended by distalmost cauline leaf, clusters sometimes in subcorymbiform arrays). Involucres turbinate, 4–5 mm. Phyllaries in 3(–4) series, whitish to slightly tawny (hyaline, shiny), narrowly triangular to narrowly oblong-triangular, glabrous. Pistillate florets 25–28. Bisexual florets 6–7. Cypselae not ridged, smooth.

Flowering (Jul–)Aug–Sep. Mostly bare sandstone cliff faces, ledges, and cracks, s- to e-facing, commonly shaded; 200–300 m; Wis.

Pseudognaphalium saxicola probably is an evolutionary derivative of P. obtusifolium. Plants of P. saxicola are relatively small and have relatively few, relatively small heads and occur in a specialized habitat; they constitute the only narrowly endemic species of Pseudognaphalium in the United States. Depauperate individuals of P. obtusifolium from localities over its whole geographic range may sometimes be as short as 5–10 cm and similar in habit to P. saxicola; such plants differ from P. saxicola in their close and denser stem vestiture, bicolor and relatively narrow leaves, larger heads with greater numbers of pistillate florets, and broader phyllaries with rounded apices.


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