Cirsium altissimum (L.) Spreng.

Cirsium altissimum plant

Family - Asteraceae

Stems - To +3m tall, branching, herbaceous, erect, striate, pubescent.

Cirsium altissimum stemStem.

Leaves - Alternate, typically glabrous above, densely pubescent to lanate below, mostly entire with spined margins, sometimes lobed, to +30cm long, +10cm wide, sessile or short-petiolate, typically lanceolate, oblong, or elliptic, reduced towards apex.

Cirsium altissimum leafAbaxial surface of leaf.

Cirsium altissimum basalsBasal rosette.

Inflorescence - Single flower heads terminating stems.

Involucre - To 3.5cm tall, +3cm wide, subglobose to vase-shaped. Phyllaries imbricate, appressed, spine (bristle) tipped, typically with a lighter midrib.

Cirsium altissimum involucreInvolucre with the subtending bracts.

Cirsium altissimum involucreInvolucre with the subtending bracts removed.

Ray flowers - Absent.

Disc flowers - Corolla pink to rose, to +30mm long, tubular, 5-lobed. Style well exserted. Achenes to 6mm long, 2mm wide. Pappus of numerous plumose bristles.

Cirsium altissimum flowers

Cirsium altissimum flowerIndividual floret.

Flowering - July - October.

Habitat - Dry woodlands, slopes, thickets, disturbed sites, waste ground, roadsides, railroads.

Origin - Native to U.S.

Other info. - This is the tallest of the plants in this genus in Missouri (altissimum means "the tallest"). It is very common throughout the state except for the extreme southeastern corner. It is a common roadside plant in the Ozarks.
Steyermark lists a couple of forms for the species. The plant pictured above is form altissimum. This plant has the typical rose-pink corolla. Form moorei has a white corolla and is listed in the "White flowers alternate" section of this website. The latter is much less common.

Photographs taken in the Ozark Scenic Riverways, Shannon County, MO., 8-9-03.