noun
1. : a smartweed ( Polygonum hydropiper )
2. : any of several plant diseases characterized by reddening of the foliage: as
a. : a nonparasitic disease of oats of uncertain cause
b. : a disease of the pear and grape caused by nutritional disturbances producing dark red or purplish red discoloration of the leaves
3. : a high grade of Burley tobacco comprised of leaves from near the top of the stalk