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Dense Spike Blackroot

Pterocaulon pycnostachyum (Michx.) Ell.

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Differences between Pterocaulon pycnostachyum and P. alopecuroides (Lamarck) de Candolle, which is widespread in the West Indies and South America, are these: plants 50–70 cm high in P. pycnostachyum (versus 70–150 cm in P. alopecuroides), arrays of heads 4–8 cm (versus 3–17 cm) long, involucres 3.5–4 mm (versus 4.5–5 mm) high, and 6–15 (versus 1–3) functionally staminate florets (A. L. Cabrera and A. M. Ragonese 1978). In P. alopecuroides, the arrays of heads are almost always interrupted proximally, commonly producing sessile to subsessile branches. A count of functionally staminate florets provides a clear determinant for plants that might appear ambiguous in other features.
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Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 19: 476 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
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Flora of North America @ eFloras.org
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Description

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Plants 2–8 dm. Leaf blades lance-olate to obovate-lanceolate, oblong, or elliptic, 3–11 × 1–3(–3.5) cm, lengths mostly 2–7 times widths, margins usually dentate or denticulate, slightly repand, sometimes nearly entire. Heads in dense, usually contin­uous, rarely interrupted (then near bases), narrow, ± ovoid arrays (2–)3–8(–10) cm (usually single, sometimes with 1–2 basal branches). Involucres campanulate, 4–5 mm. Pistillate florets 23–44. Functionally staminate florets 6–10(–15). Cypselae 1–1.3 mm. 2n = 20.
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cc-by-nc-sa-3.0
copyright
Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 19: 476 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of North America @ eFloras.org
editor
Flora of North America Editorial Committee
project
eFloras.org
original
visit source
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eFloras

Synonym

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Conyza pycnostachya Michaux, Fl. Bor.-Amer. 2: 126. 1803; Pterocaulon undulatum C. Mohr
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cc-by-nc-sa-3.0
copyright
Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 19: 476 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of North America @ eFloras.org
editor
Flora of North America Editorial Committee
project
eFloras.org
original
visit source
partner site
eFloras

Pterocaulon pycnostachyum

provided by wikipedia EN

Pterocaulon pycnostachyum, with the common names dense-spike blackroot,[3] fox-tail blackroot or coastal blackroot, is a plant species native to Alabama, Mississippi, North Carolina, Florida, Georgia, and South Carolina. It can be found in pinelands, ditches, depressions, and fields.[4][5]

Pterocaulon pycnostachyum is a perennial herb up to 80 cm (31 inches) tall. Stems and the underside of leaves are covered with a thick, white layer of woolly hairs. Flower heads are crowded into a densely packed spike at the tips of the branches. Each head has as many as 50 small yellowish flowers. The plant is monoecious, meaning that some of the flowers have male stamens, while female pistils are in separate flowers in the same head.[4][6][7][8][9]

References

  1. ^ Tropicos
  2. ^ The Plant List
  3. ^ "Pterocaulon pycnostachyum". Natural Resources Conservation Service PLANTS Database. USDA. Retrieved 15 October 2015.
  4. ^ a b Flora of North America v 19 p 476.
  5. ^ Discover Life
  6. ^ Cabrera, A. L. and A. M. Ragonese. 1978. Revisión del género Pterocaulon (Compositae). Darwiniana 21: 185–257.
  7. ^ Elliott, Stephen. Sketch of the Botany of South-Carolina and Georgia 2(4): 324. 1824.
  8. ^ Michaux, André. Flora Boreali-Americana 2: 126. 1803.
  9. ^ Southeastern Flora
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Pterocaulon pycnostachyum: Brief Summary

provided by wikipedia EN

Pterocaulon pycnostachyum, with the common names dense-spike blackroot, fox-tail blackroot or coastal blackroot, is a plant species native to Alabama, Mississippi, North Carolina, Florida, Georgia, and South Carolina. It can be found in pinelands, ditches, depressions, and fields.

Pterocaulon pycnostachyum is a perennial herb up to 80 cm (31 inches) tall. Stems and the underside of leaves are covered with a thick, white layer of woolly hairs. Flower heads are crowded into a densely packed spike at the tips of the branches. Each head has as many as 50 small yellowish flowers. The plant is monoecious, meaning that some of the flowers have male stamens, while female pistils are in separate flowers in the same head.

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