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    The Gayophytum genus consists of about 9 species, one (G. micranthum) is found only in South America and seven only in in North America. The first species in the genus, G. humile, discovered by Claude Gay in Argentina around 1830, is found on both continents.

    Click for the 1964 Lewis and Szweykowski thorough study and revision of the Gayophytum genus. The study indicates, "Gayophytum presents a baffling array of morphological variation which does not seem to fall into clearly distinct units...." In particular, G. diffusum (shown below) has a "complexity and diversity of the pattern of morphological variation...." Lewis and Szweykowski concluded that the genus has few morphological traits that help separate one species from another. The branching pattern and the characteristics of the capsule are best for distinguishing species.

    All floras now base their treatment of Gayophytum on Lewis and Szweykowski's superb work, but all still recognize the difficulty of the Gayophytum genus:

"Most of the specific boundaries are obscure." "The genus does not lend itself to the preparation of a practical and easy key for identification." (Cronquist).

"A difficult genus... [with] overlapping morphology.... The following arbitrary key is tentative at best". (Welsh)

"Good luck!" (Weber)

Gayophytum diffusum

Gayophytum diffusum

Gayophytum diffusum

Gayophytum diffusum subspecies parviflorum (Spreading Groundsmoke)
Onagraceae (Evening Primrose Family)

Foothills, montane, sub-alpine. Openings, woodlands, shrublands. Summer, fall.
Prater Ridge Trail, Mesa Verde National Park, July 1, 2016.

As the photographs indicate, Gayophytum diffusum is a wisp of a plant that blends in with the greenery around it. It has several attributes that do make it attract your attention: 1) A dozen or more plants often grow quite close to each other. 2) Stems are red. The arrows in the photograph above point to just four of the dozen or so plants in the same area.

Plants grow to nearly two feet and branch often.

Adrien Jussieu, botanist and son of the great Antoine Jussieu, named this genus in 1832 to honor fellow botanist and countryman, Claude Gay, who discovered in the mountains of St. Jago, Chile, the species that Jussieu named Gayophytum humile.

Torrey and Gray named and described G. diffusum in 1840 from a specimen collected by Nuttall in Oregon in 1834. Lewis & Szweykowski named the subspecies. (Click for more biographical information about Gay.)

"Phytum" is Greek for "plant" and "diffusum" is Latin for "diffuse, spreading".

Gayophytum diffusum

Gayophytum diffusum

Gayophytum diffusum subspecies parviflorum (Spreading Groundsmoke)
Onagraceae (Evening Primrose Family)

Foothills, montane, sub-alpine. Openings, woodlands, shrublands. Summer, fall.
Prater Ridge Trail, Mesa Verde National Park, July 1, 2016.

Plants branch freely and this plus the maroon/red stems attract attention.

Leaves are linear, up to 6 cm long, but just 5 mm wide. Leaves are alternate and often single but they also occur in bundles.

At first glance some leaves appear to be opposite, but a second look shows that some nodes produce several leaves with some wrapping to one side of the stem and some to the other side. That first glance may also convince you that instead of the normal alternate leaf arrangement (a leaf on one side of the stem, then another leaf higher up on the other side of the stem), this plant has a leaf on one side of the stem and then the next leaf higher up is on the same side of the stem. Again, if you take another look you will see that some leaves wrap around the stem so that often the alternate leaves appear to be secund.

                                 Gayophytum diffusum

Gayophytum diffusum

Gayophytum diffusum

Gayophytum diffusum

Gayophytum diffusum subspecies parviflorum (Spreading Groundsmoke)
Onagraceae (Evening Primrose Family)

Foothills, montane, sub-alpine. Openings, woodlands, shrublands. Summer, fall.
Prater Ridge Trail, Mesa Verde National Park, July 1, 2016.

Flowers open in the morning and are withered by noon or, on cloudy days, may close by mid-afternoon. Flowers are minute, with petals just 1.5 to 6 mm long. Petals shown are 4 mm long.

Sepals are slightly smaller than petals and they are strongly reflexed, as shown in the upper right of the third photograph at left.

The position of the flowers is one helpful characteristic in distinguishing Gayophytum species. Some species begin flowering in the lower nodes; some not until the tenth node. Some populations of G. diffusum subspecies parviflorum, however, can flower at any node position.

The manner in which the capsule opens, the length of the pedicels, the number of seeds, and the position of the seeds is key to identifying the different species of Gayophytum. Again, however, G. diffusum has a wide range in all these characteristics. Seed capsules range from 5-15 mm and seeds range from just 3 to 18 in number. See the tan mature 15 mm capsule in the lower photograph at left. The arrow points to the pedicel, which in this species of Gayophytum, is much shorter than the capsule but can range from 2 to 15 mm.

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

Gayophytum diffusum subspecies parviflorum

Range map for Gayophytum diffusum subspecies parviflorum