Date: XXXXXXXX 2010. Location: XXXXXXXXX(map)
| Classification Hierarchy | |
| Kingdom | Plantae |
| Subkingdom | Tracheophyta |
| Superdivision | Spermatophyta |
| Division | Magnoliophyta |
| Subclass | Asteridae |
| Order | Asterales |
| Family | Asteraceae |
| Genus | Cirsium |
| Species | Cirsium discolor |
Date: XXXXXXXX 2010. Location: XXXXXXXXX(map)
Scientific Name: Cirsium discolor
Common Name: Field thistle
Origin: Native
Notes: Designated a "Primary Noxious Weed" by Iowa weed law.
A biennial (sometimes perennial) plant with a strong taproot system.
Additional references: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
Flowers: purplish-pink to white; heads 1-many; involucres 2.5-3 cm high, thinly arachnoid; phyllaries spines abruptly spreading to deflexed, spines slender 3 to 9 mm long; cypselae tan to brownish, 4-5 mm long, pappi 18 to 25 mm.
Stems: erect with few to many branches ascending; strongly furrowed, greenish, villous with septate trichomes, sometimes smooth or tomentose; 2 to 6 feet high.
Leaves: prickly and numerous, cauline and basel leaves deeply pinnatifid; above—green and glabrous or with short stiff hairs, below—blanketed with dense white hair; uppermost sessile leaves form a false involucre.
Glossaries of botanical terms: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
