Denver EcoFlora Project's Journal

One of the most speciose genera in the world is that of Astragalus, with an estimated 3000 species globally. Astragalus is also a common member of the western landscape, with an estimated 117 species present in Colorado alone – and within the greater Denver metro area, 28 different Astragalus species have been documented.

Astragalus is a member of the pea, or Fabaceae, family. It exhibits typical characteristics of this family such as bilaterally symmetrical flowers with the petals comprised of three parts – an erect banner, two lateral wings, and a keel (two petals fused together, resembling a keel boat). These plants often have pinnately compound leaves as well. Astragalus differs from the closely related genus Oxytropis by the shape of the keel petal – in Oxytropis, the keel petal is narrowed and beak-like at the tip, but only tapered to a point in Astragalus flowers. As with all members of the pea family, the fruit type for Astragalus is a legume.

Although 28 species of Astragalus have been documented from the greater metro area, some of our most common species found blooming in the spring are: (A.) A. agrestis, (B.) A. bisulcatus, (C.) A. crassicarpus, (D.) A. drummondii, (E.) A. missouriensis, (F.) A. parryi, (G.) A. shortianus, and (H.) A. tridactylicus. Astragalus bisculatus or two-grooved milkvetch (named for the two grooves on the top of each legume), can even hyperaccumulate selenium (a heavy metal found in the soil) in its tissues. Astragalus crassicarpus, or ground plum, gets its name from the plum-like legumes produced.

There is even one Astragalus that has not been seen in Colorado for over 100 years – A. americanus. This Astragalus is only known from two historical collections made in 1874 and 1892. It should be sought after in moist pine forests of the southwestern part of greater metro area, most likely in the Pike National Forest.

See if you can locate an Astragalus or two! Help Denver Botanic Gardens document the diversity of Astragalus in the metro area by photographing as many plants as possible in the month of May. Post your findings to iNaturalist so they will automatically be added to the Denver EcoFlora Project.

Astragalus bisulcatus:

WHAT IS AN ECOQUEST?
EcoQuests, part of the Denver EcoFlora project, challenge citizens to become citizen scientists and observe, study, and conserve the native plants of the City via iNaturalist, an easy-to-use mobile app.

HOW DO I GET STARTED?

1. Download the iNaturalist app or register online at iNaturalist.org
2. Take photos of the plants in bloom that you find on your daily neighborhood walk. It is ok if they are weeds! But avoid taking photos of cultivated plants in gardens or in your home.
3. If you are concerned about revealing the location of sensitive organisms or observations at your own house, you can hide the exact location from the public by changing the "geoprivacy" of the observation to "obscured."
4. Post your findings on iNaturalist via the app
5. Your observations will automatically be added to the Denver EcoFlora Project
6. You can add an identification to your photo when you post your findings on iNaturalist, or leave it blank for others to identify.

WHAT IS THE GOAL?
The EcoFlora project is designed to meaningfully connect citizens with biodiversity, and to assemble novel observations and data on the metro area’s flora to better inform policy decisions and conservation strategies.