Compilation
Gamochaeta pensylvanica

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Name

Identification
Gamochaeta pensylvanica (Willd.) Cabrera [family ASTERACEAE ] (stored under name); Verified by Not on sheet, Gnaphalium spathulatum Lam. [family ASTERACEAE ] Verified by Not on sheet,
Related name
  • Gnaphalium spathulatum
  • Gamochaeta pensylvanica
Common name
  • Pennsylvania cudweed, Flora of North America Vol. 19

Flora

Entry for Gamochaeta pensylvanica (Willdenow) Cabrera [family COMPOSITAE]
Herbarium
Flora of North America (FNA)
Collection
Flora of North America
Resource Type
Reference Sources
Entry From
Flora of North America, Vol 19,
Names
Gamochaeta pensylvanica (Willdenow) Cabrera [family COMPOSITAE], Bol. Soc. Argent. Bot., 9: 375. 1961
Gnaphalium pensylvanicum Willdenow [family COMPOSITAE], Enum. Pl., 867. 1809,. based on G. spathulatum Lamarck in J. Lamarck et al., Encycl. 2: 758. 1788, not Burman f. 1768
Gnaphalium peregrinum Fernald [family COMPOSITAE]
Treatment Author(s)
Guy L. Nesom
Information
Annuals, 10–50 cm; taprooted. Stems erect to decumbent or procumbent, loosely arachnose-tomentose. Leaves basal and cauline, proximal usually present at flowering, blades spatulate to oblanceolate-obovate, 2–7 cm × 4–16 mm (becoming spatulate to oblanceolate bracts among proximal heads, surpassing glomerules, bases narrowed to petiolar regions, margins sinuate, apices often apiculate), faces concolor or weakly bicolor, loosely tomentose. Heads in glomerules in continuous or interrupted, spiciform arrays 1–12 cm × 10–15 mm (pressed). Involucres cupulate-campanulate, 3–3.5 mm, bases sparsely arachnose. Phyllaries in 3–4 series, outer ovate-triangular, lengths 1/2–2/3 inner, apices attenuate-apiculate, inner oblong, laminae often purple-tinged (at stereome), apices (transparent, sometimes golden) acute to obtuse. Florets: bisexual 3–4; all (or at least bisexual) corollas usually purplish distally. Cypselae (tan) 0.4–0.5 mm. 2n = 28.
Phenology
mar-may (spring), jun, aug (summer)
Altitude range
0–500 m;
Distribution
MexicoCentral AmericaSouth AmericaEuropeAsiaAfricaAustralia.USA Ala.USA Calif.USA Fla.USA Ga.USA La.USA Md.USA Mass.USA Miss.USA N.C.USA Okla.USA Pa.USA S.C.USA Tex.USA Va.
Discussion
Gamochaeta pensylvanica is recognized by its obovate-spatulate, loosely tomentose and concolor or weakly bicolor basal and proximal cauline leaves, and similarly shaped spreading bracts among the heads. Occasional plants appear intermediate between G. pensylvanica and G. antillana. The latter differs in its more erect stems, linear to oblanceolate basal and proximal cauline leaves, and more nearly continuous arrays of heads with linear to narrowly oblanceolate bracts.

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