What does "bluestem" mean?

Any of various grasses having bluish stems, including little bluestem and big bluestem.

Bluestem

Common synonyms include: andropogon gerardii, andropogon furcatus, blue stem, prairie grass, schizachyrium scoparium, tallgrass prairie grass.

/ˈbluːstɛm/ noun

noun ·Rare ·Advanced level

Noun

1
Any of various grasses having bluish stems, including little bluestem and big bluestem. US, uncountable, usually
"Then we were going at a lope with the bluestem whipping our legs."
2
tall grass with smooth bluish leaf sheaths grown for hay in the United States wordnet

"Then we were going at a lope with the bluestem whipping our legs."

From blue + stem.