Downy Brome: shoots and leaves often show a reddish-purple tinge over the winter months.

• A. Russian Thistle
• B. Downy Brome
• C. Prickly Pear
• D. Broom Snakeweed

Answer: (B)

Winter tissue color changes in grasses are often due to anthocyanin pigments that build up under cold stress, giving shoots and leaves a reddish-purple tint. Downy Brome, a winter annual grass, commonly shows this reddish-purple coloration on its new growth during colder months, making it a distinctive clue for identifying it in the field. The other plants listed—Russian Thistle, Prickly Pear, and Broom Snakeweed—do not typically display this characteristic winter color pattern on their shoots and leaves, so the reddish-purple tint specifically points to Downy Brome.