Cirsium horridulum

Cirsium horridulum
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Asterales
Family:	Asteraceae
Subfamily:	Carduoideae
Tribe:	Cynareae
Genus:	Cirsium
Species:	C. horridulum
Binomial name
Cirsium horridulum Michx.
Synonyms[1]
Synonymy Carduus horridulus Pers. Carduus pinetorum Small Carduus spinosissimus Walter Carduus vittatus Small, syn of var. vittatum Cirsium chrismarii (Klatt) Petr. Cirsium pinetorum (Small) Small 1913 not Greenm. 1905 Cirsium vittatum (Small) Small, syn of var. vittatum Cnicus chrismarii Klatt Cnicus horridulus (Michx.) Pursh Cirsium megacanthum Nutt., syn of var. megacanthum Carduus smallii (Britton) H.E.Ahles, syn of var. vittatum Cirsium smallii Britton, syn of var. vittatum

Cirsium horridulum, called bristly thistle, horrid thistle, yellow thistle or bull thistle, is a North American species of plants in the thistle tribe within the sunflower family. The species is native to the eastern and southern United States from New England to Florida, Texas, and Oklahoma as well as to Mexico, Belize, Guatemala, Honduras, and the Bahamas.^{[2][3][4][5][6]}

Thomas Nuttall (1786-1859) described var. megacanthum as "one of the most terribly armed plants in the genus."^[7][8]

Cirsium horridulum is a biennial or perennial herb up to 250 cm (100 inches) tall, with a large taproot and fleshy side roots that sometimes sprout new shoots. Leaves are up to 40 cm (16 inches) long with thick, sharp spines along the edges. There are usually several flower heads, also with sharp spines, each head with disc florets but no ray florets. Flower color varies from one plant to the next: white, yellow, pink, red or purple.^[9]

Varieties^[1][9]

• Cirsium horridulum var. horridulum - from Maine to Guatemala
• Cirsium horridulum var. megacanthum (Nutt.) D.J.Keil - from the Florida Panhandle to Texas and Oklahoma
• Cirsium horridulum var. vittatum (Small) R.W.Long - from North Carolina to Louisiana

References

1. The Plant List, Cirsium horridulum Michx.
2. Biota of North America Program 2014 county distribution map
3. Davidse, G., M. Sousa-Peña, S. Knapp & F. Chiang Cabrera. 2015. Asteraceae. 5(2): ined. In G. Davidse, M. Sousa Sánchez, S. Knapp & F. Chiang Cabrera (eds.) Flora Mesoamericana Universidad Nacional Autónoma de México, México D.F..
4. Carnevali, G., J. L. Tapia-Muñoz, R. Duno de Stefano & I. M. Ramírez Morillo. 2010. Flora Ilustrada de la Peninsula Yucatán: Listado Florístico 1–326
5. Nelson, C. H. 2008. Cat. Pl. Vasc. Honduras 1–1576. Secretaria de Recursos Naturales y Ambiente, Tegucigalpa
6. Nash, D. L. 1976. Tribe IX, Cynareae. En: Nash, D.L. & Williams, L.O. (eds), Flora of Guatemala - Part XII. Fieldiana, Bot. 24(12): 423–428, 590
7. Nuttall quoted in Flora of North America, Bigspine thistle, Cirsium horridulum Michaux var. megacanthum (Nuttall) D. J. Keil
8. Nuttall, Thomas 1841. Transactions of the American Philosophical Society, new series 7: 421 as Cirsium megacanthum
9. Flora of North America, Bristly or horrid or yellow or bull thistle, Cirsium horridulum Michaux, Fl. Bor.-Amer. 2: 90. 1803.

External links