With its pure red flowers, Cardinalflower, Cardinal Flower, or Scarlet Lobelia (Lobelia cardinalis) is one of the most brightly colored wildflowers in North America. Cardinalflower is found growing in moist areas throughout much of the United States, including here in Arizona. With August thunderstorms rumbling nearby, I observed this blooming Cardinalflower in a riparian meadow along Arizona's Sycamore Canyon Trail near the Mexican border.
Cardinalflower is a perennial herb with alternate, toothed, oblong, green leaves and red (rarely white), tubular, 5-lobed (2 upper and 3 lower) flowers on upright stems up to 5 feet (1.5 m) tall, but usually much less. Here in southeastern Arizona, the flowers bloom with the summer monsoon rains.
Although it requires moist soil and is not drought tolerant, this native wildflower is cultivated as an ornamental plant, and it makes an especially nice addition to natural wildflower gardens because the red flowers attract hummingbirds. Cardinalflower is not a popular garden plant here in hot, arid Arizona, but it does quite well in areas with more rainfall in the eastern parts of North America.
Because it contains the alkaloid Lobeline, Cardinalflower is poisonous, but like many other poisonous plants, its toxins can have medicinal uses if carefully dosed and prepared (beware of using it as a home remedy). Lobeline is used to treat nicotine addiction in smoking cessation, and it may be useful for treating other forms of drug addiction as well.