From a distance Thelypodiopsis aurea might be taken for Stanleya pinnata but up-close the two are distinct.  Blooming time also helps to separate the two: T. aurea blooms in March and April, S. pinnata in May, June, and later.  Both plants like growing in selenium rich soils; T. aurea is especially pungent from the selenium. 

T. aurea grows to three feet tall, its leaves are sage green with basal leaves in a large mound, and its bright yellow tubular flowers with four flared petals are subtended by four bright yellow sepals (the narrow yellow structures below the floral tube in the photograph immediately below).

This species was first collected by Alice Eastwood in Mancos, Colorado in 1891. Eastwood named the new species Thelypodium aureum. 

Per Axel Rydberg named the Thelypodiopsis genus in 1907 putting in it several species that had previously been incorrectly placed in the Thelypodium genus.  "Thelypodiopsis" means "resembling a small Thelypodium". "Aurea" is Latin for "golden".

I do not know why the word "Durango" is used as one of the common names ("Durango Tumble Mustard"), since there are no records of it occuring in Durango, Colorado or in La Plata County. As mentioned above, the plant was discovered in Mancos, Colorado (Montezuma County).

As the map below indicates, Thelypodiopsis aurea is a Four Corners endemic.

Semi-desert. Openings. Spring.
McElmo Canyon, Canyon of the Ancients National Monument, March 24, 2016.

Lowest leaves (left corner arrow) wither as the flower stem elongates.

Basal leaves (left corner arrow and second arrow from bottom) have a petiole and are coarsely toothed. 

Upper leaves (top two arrows) are sessile and auriculate, i.e., they have ear-like lobes that clasp the stem.

Leaves are reduced in size upward and leaves of new plants are also quite reduced in size.

Flower stems elongate quickly and can rise to several feet. Notice the tiny siliques (the seed pods) beginning to extend themselves from the lower flowers and one long, arching pod in the lower left of the top photograph.

Eventually all flowers fade and long, wavy siliques on short pedicels end the growing season.

Silique length, shape (long and narrow or round and flattened), and curvature are key diagnostic characteristics for Brassicaceae.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Thelypodiopsis aurea