Pseudognaphalium leucocephalum |
Pseudognaphalium arizonicum |
|
---|---|---|
white cudweed, white rabbit-tobacco |
Arizona cudweed, Arizona rabbit-tobacco |
|
Habit | Biennials or short-lived perennials, 30–60 cm; taprooted. | Annuals or perennials, 20–50 cm; taprooted. |
Stems | densely and persistently white-tomentose, usually with stipitate-glandular hairs protruding through tomentum. |
loosely and densely woolly-tomentose (hairs usually with reddish or purplish cross walls), not glandular. |
Leaf | blades (crowded, internodes mostly 1–3, sometimes to 10 mm) linear-lanceolate, 3–7 cm × 1–5(–6) mm, bases subclasping, not decurrent, margins strongly revolute, faces bicolor, abaxial densely white-tomentose, adaxial green, densely stipitate-glandular. |
blades linear-oblanceolate to linear-lanceolate, 2–6 cm × 2–7 mm, bases not clasping, decurrent 3–15(–20) mm, margins weakly and narrowly revolute, faces concolor to weakly bicolor, tomentose (hairs commonly with reddish or purplish cross walls), not glandular. |
Involucres | broadly campanulate, 5–6 mm. |
turbinate-campanulate, 5–6 mm. |
Pistillate florets | 66–85. |
(25–)30–49. |
Bisexual florets | (6–14, California)29–44. |
(1–)3–6. |
Phyllaries | in 5–7 series, bright white (opaque, dull), oblong to oblong-ovate, glabrous. |
in 4–5 series, usually brownish to tawny, rarely slightly rosy (opaque, shiny), ovate-lanceolate to lanceolate, glabrous. |
Heads | in corymbiform arrays. |
borne singly or in terminal glomerules or corymbiform arrays. |
Cypselae | ridged, smooth. |
ridged, papillate-roughened. |
2n | = 28. |
|
Pseudognaphalium leucocephalum |
Pseudognaphalium arizonicum |
|
Phenology | Flowering (Jul–)Aug–Nov(–Dec). | Flowering Aug–Sep. |
Habitat | Sandy or gravelly slopes, stream bottoms, arroyos, areas of oak-sycamore, oak-pine, to pine woodlands, commonly in riparian vegetation | Open woodlands and chaparral [wide ranging habitats in Mexico, agricultural land to oak and pine woodlands] |
Elevation | 50–2100 m (200–6900 ft) | 1600–2300 m (5200–7500 ft) |
Distribution |
AZ; CA; NM; Mexico (Baja California, Baja California Sur, Chihuahua, Durango, Sinaloa, Sonora)
|
AZ; TX; w Mexico |
Discussion | Pseudognaphalium leucocephalum is similar to P. viscosum, which has shiny, hyaline, ovate-lanceolate phyllaries, 200–250 pistillate florets, (13–)16–29 bisexual florets, and papillate-roughened cypselae. Some plants of P. leucocephalum also appear to approach P. biolettii in general appearance, and it is possible that some of them may represent hybrids. Plants of P. biolettii differ from P. leucocephalum in their typically eglandular stems, broader, basally ampliate, clasping, more widely spaced, and less densely glandular leaves, and thinner, shiny phyllaries. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Pseudognaphalium arizonicum is superficially similar to P. stramineum in its narrow, concolor leaves; P. stramineum has non-decurrent leaves, light yellowish phyllaries, and more pistillate and bisexual florets. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 19, p. 423. | FNA vol. 19, p. 424. |
Parent taxa | Asteraceae > tribe Gnaphalieae > Pseudognaphalium | Asteraceae > tribe Gnaphalieae > Pseudognaphalium |
Sibling taxa | ||
Synonyms | Gnaphalium leucocephalum | Gnaphalium arizonicum |
Name authority | (A. Gray) Anderberg: Opera Bot. 104: 147. (1991) | (A. Gray) Anderberg: Opera Bot. 104: 147. (1991) |
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