Blue Mustard flowers - Naturalist Perspective

Blue mustard plants are among the earliest blooms seen out in the Willow Spring Open Space, with blooms starting in April and continuing through June. They have tiny purple blooms with four petals that are each only 1/4-1/2″ long.

They are also sometimes called Crossflowers, as the petals form a perfect cross.

These plants are annual herbs, which means that the plant dies each winter and new plants are grown in the spring from seeds.

The entire plant ranges from only 4 – 12 inches tall. This is an abundant, common weed of dry roadsides and disturbed areas. It is not a native plant to Colorado; it originated in Southwest Asia.

Blue mustard blooms with ruler — Blue mustard blooms close-up

There are basal leaves (at the base of the plant) which are oblongs, 1-2″ long with wavy edges, and also leaves along the stem. The fruit, or seed pod, looks like a stem coming off of the plant, rising up to the right in the plant shown above.

Scientific Name and Plant Family Information

The Scientific name for the Blue Mustard plant is Chorispora tenella. Chorispora is from the Greek for chori – separated spora – seed, referring to how the seeds grow in the seed pods. Tenella is Latin for tender or delicate.

It is in the plant family Brassicaceae (Mustard or Cabbage), which also has radishes, wallflowers and alyssum.

Many plants in this family have a similar life cycle; they shoot up fast in the spring, bloom and then set seed and die while other plants are just getting going.

Most of the plants in the Brassicaceae family have yellow blooms, so the family name is easy to remember as it starts with Brass. These flowers all have four petals and set seed in seed pods.

Through the Seasons

The Blue Mustard plants start blooming in April and end in June when they set seed for the next year.

Native or Non-Native?

Blue Mustard plants are non-native to this area, coming from Southwest Asia. They are well adapted to colonizing bare ground, so spread easily here in Colorado and are found at elevations from 4,000 to 9,500 feet.

Where to find in Willow Spring Open Space

Blue mustard plants are along most of the paths in the Willow Spring Open Space, although after June they will all have stopped blooming and will be harder to spot.

Did You Know?

The mustard that we use for food comes from the ground seeds of a related plant in the Brassicaceae (Mustard) family. Many vegetables are also in this family, including cabbage, cauliflower, kohlrabi, Brussel sprouts, broccoli and kale.