Nabalus altissimus (L.) Hook.
Rough White Lettuce, Rattlesnake Root
Family - Asteraceae
Stem - Erect, to 2 m, usually glabrous, often with purple coloration, sometimes glaucous.
Leaves - Variable. Springtime emergent leaves often deeply lobed or with indistinct hastate lobes at bases. Lower cauline leaves petiolate, usually lobed, usually with a few broad, shallow teeth. Upper cauline leaves progressively smaller, with shorter petioles, less often lobed.
Lower stem leaf.
Upper stem leaf.
Inflorescence - Typically broad panicles, with heads tending to cluster. Heads nodding.
Involucre - 9-14 mm long, cylindrical, with short outer bracts and 4-6 longer, pale greenish inner bracts.
Flower - Ligulate florets 4-6, cream to yellow, with 5-6 mm orange-brown pappus.
Fruit - 4-5 mm long, light brown or yellowish brown.
Flowering - July - October.
Habitat - Streambanks, mesic and bottomland forests, bluffs.
Origin - Native to North America.
Other info - This is the species of Nabalus most often encountered in Missouri. It is easily recognized
by its open inflorescences and narrow heads with smooth involucres. It is most commonly found in moist areas with light to moderate shade.
It seems to be a favorite of deer, which will often browse it preferentially over other vegetation.
Photographs taken at Taum Sauk State Park, Iron County, MO, 9-27-2010, Young Conservation Area, Jefferson County, MO, 9-24-2014, Valley View Glade Natural Area, Jefferson County, MO, 9-28-2014, and Glassberg Conservation Area, Jefferson County, MO, 9-25-2015 (SRTurner).