Weed No. 5. Barnyard Grass (Echinochloa crus-galli)

Farmers detest this European grass for its ready invasion of most crops. The plant can also invade and destroy native grassland vegetation in areas disturbed by grazing livestock. Otherwise, Barnyard Grass serves as a colonizer and successional species that is steadily replaced by longer-lived species. In one research study, other species replaced it in about 10 years.

In the arid climate of central Arizona, the plant survives along moist stream banks and in bare spots in and beside watered lawns and gardens. The plant is easy to control by mowing or withholding water. However, if you allow a few clumps to grow, you will get to enjoy watching the acrobatics of Lesser Goldfinches that relish Barnyard Grass seeds. The small birds hang (often upside down) on drooping seed tops steadily removing mature seeds until all are gone. The birds must drop some seeds, however, as new plants appear in the same spots every spring.

Six-foot tall clump of Barnyard Grass

Lesser Goldfinch showing his tail feathers as he hangs beak down polishing off Barnyard Grass seeds.

Barnyard Grass (Echinochloa crus-galli). This strong summer annual matures at ½ to 6 feet tall and often spreads from its base to form large clumps. The leaves are 4 to 20 inches long and ¼ to ¾ inches wide. Flowering occurs along the top 3 to 10 inches of the stem. Flowering branches are 1 to 2 ¼ inches long with short green or purple spikelets 1/8 inch long with bristles up to 1 ½ inches long. A single plant can produce 40,000 of the pale yellow shiny seeds. A. Spikelet spread open. B. Two spikelets with short and long awns. C. Grain. Image used with permission of the University of Arizona Press.

Weed No. 4. Barestem Larkspur (Delphinium scaposum)

This is the most widespread of nine native Larkspur species in Arizona. Commercial seed packages often contain several of the species. Larkspur spreads across disturbed areas and flowers spring through summer. Plants are drought tolerant. New shoots from the plant’s root system form persistent colonies. My colonies have usually lasted only a year or two. I suspect that supplemental watering that benefits other flowers rotted the roots and prevented patch persistence and spread.

The plant’s foliage poisons cattle, but the flowers are fabulous insect magnets. Butterflies, bees, flies, and moths of many species like the nectar. Around my house, it’s the most popular flower for bumblebees including the big shiny black carpenters.

Larkspur (mostly at left) blends well with the Black-Oil Sunflowers that volunteer in places where I feed birds. (Photo: GR)

Barestem Larkspur (Delphinium scaposum). This gray-green perennial reproduces from seed and from clusters of dark woody roots. The stems reach ½ to 2 ½ feet high. Flowers are vivid royal blue with long basal spurs. A. Seed pod (3/8 to ¾ inches long). B. Seed (1/8 inch). (Drawing used with permission of the University of Arizona Press.)