Pterocaulon pycnostachyum

(Michaux) Elliott

Sketch Bot. S. Carolina 2: 324. 1823.

Common names: Fox-tail or coastal blackroot
Endemic
Basionym: Conyza pycnostachya Michaux Fl. Bor.-Amer. 2: 126. 1803
Synonyms: Pterocaulon undulatum C. Mohr
Treatment appears in FNA Volume 19. Treatment on page 476.

Plants 2–8 dm. Leaf-blades lanceolate 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.


Phenology: Flowering May–Jun.
Habitat: Sandy pinelands, sandy fields, depressions, ditches
Elevation: 0–20 m

Distribution

V19-799-distribution-map.gif

Ala., Fla., Ga., Miss., N.C., S.C.

Discussion

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.

Selected References

None.

Lower Taxa

None.
... more about "Pterocaulon pycnostachyum"
whitish-tomentose +
glabrescent +  and glabrous +
obtuse;rounded +
scarious +
ovate +  and lanceovate or linear +
indeterminate +  and determinate +
Guy L. Nesom +
(Michaux) Elliott +
decurrent +
Conyza pycnostachya +
compound +  and simple +
obovate;elliptic +
ribbed;smooth +
Fox-tail or coastal blackroot +
cylindric +  and fusiform angled or slightly compressed +
Ala. +, Fla. +, Ga. +, Miss. +, N.C. +  and S.C. +
0–20 m +
sessile-glandular +  and stipitate +
usually sparsely strigose +  and hispidulous +
staminate +  and pistillate +
winged +  and beaked +
dispersed +
Sandy pinelands, sandy fields, depressions, ditches +
8 cm80 mm <br />0.08 m <br /> (10 cm100 mm <br />0.1 m <br />) +
indeterminate +
heterogamous +
3 cm30 mm <br />0.03 m <br /> (8 cm80 mm <br />0.08 m <br />) +
each +  and sessile +
glandular +  and lanate-tomentose +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
campanulate +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
3 cm30 mm <br />0.03 m <br /> (3.5 cm35 mm <br />0.035 m <br />) +
3 cm30 mm <br />0.03 m <br /> (11 cm110 mm <br />0.11 m <br />) +
lanceolate;obovate-lanceolate oblong or elliptic +
deltate +
repand +, denticulate +  and dentate +
2-carpellate +
persistent +
Flowering May–Jun. +
Sketch Bot. S. Carolina +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
6 +  and 9 +
setiform +
exalbuminous +
appendaged +  and truncate +
papillate +
Pterocaulon undulatum +
Pterocaulon pycnostachyum +
Pterocaulon +
species +
lignescent-tuberous-rooted +  and rhizomatous +
20 cm200 mm <br />0.2 m <br /> (150 cm1,500 mm <br />1.5 m <br />) +