Several of these were scattered around, some of them in places where large grasses wouldn't be planted by reasonable gardeners, so I think at least some of these were wild.
observation for host plant: https://www.inaturalist.org/observations/141385925
By late summer, kochia becomes a tall broad tumbleweed often interconnecting with adjacent kochia plants. Long conspicuous hairs covering much of the plant and radially symmetric flowers distinguish Kochia from close relatives in the Amaranthaceae (Chenopodiaceae). This site lies near Graf Street, along the trail that follows Spring Creek, south Bozeman, Gallatin County, Montana.
just flowering; not yet set seed; there were others on campus, and they all appeared to be growing in landscaping that had received fresh wood mulch this year...wonder if seeds came in with the wood mulch...
2 styles, cespitose, stems and foliage lax, adventive in crack in concrete
Half mile from first site, literally thousands of plants from dime-sized, with flower(s), to large specimens 10” across
Escaped from plantings in adjacent park, coming up in riverbank thickets and trimmed back by beavers
The profuse golden or yellowish stems and twigs are conspicuous during non-summer months. This bark color or its intensity is lost during the summer. This site lies just to the north of Langhor Park, south of East Garfield Street, Bozeman, Montana.
The second and third photo of the leaves were taken at the end of the following September 2008.
Salix fragilis retains the bright yellow twig coloration throughout the winter until the following summer when leaves mature. This site lies at the mouth of Bear Trap Creek along the Madison River in Bear Trap Canyon, Madison County, Montana.
Salix fragilis along the Gallagator Linear trail, just south of the Peets Hill parking lot, Bozeman, Montana, remains common along Spring Creek riparian corridor. This exotic willow isn't replacing native diversity given that many other native species co-exist with fragile willow. Fragile willow is an apt common name given how winter storms often break branches of varying diameters.
Spreading slightly from cultivation
Residential roadside
Lotus corniculatus grows commonly along roadsides and trailsides in the Bozeman area and continues to grow, flower, and fruit into late summer and early fall. The umbellate inflorescence bearing flowers with bright yellow petals and the trifoliolate leaf with leaf-like stipules (superficially rendering a five-foliolate leaf) are diagnostic of this species. This site lies south of College Avenue between 11th and 12th Streets, Bozeman, Montana.
pricklets on the sepals and furry as leaves.
Three-lobed fruits emerge from flowering cups each rimmed with yellowish glands. Leafy spurge occurs along the edges of gravelly draws where they abut the sagebrush steppe, but does not occur in the Wyoming big sagebrush steppe of the Idaho National Laboratory where native plant abundance and diversity is high. This site lies just east of Lincoln Blvd along Seven Mile Road, Butte County, Idaho.
Young inflorescences. Very big rhizomatous grass. Wine-red lower internodes.
Phragmites australis in the area around Three Forks, Montana, belongs to the native subspecies, as indicated most conspicuously by its deciduous leaf sheaths that exposes reddish stems beneath.
Flickr album and species (variety) diagnosis at https://www.flickr.com/photos/plant_diversity/sets/72157687395478862/
A few plants self-sown, here and there, scattered along roadside for several miles
Perhaps a hybrid, Bidens connata x B. frondosa. Petioles generally not winged, 5 yellow rays 11-12 mm long, disk lobes orange, anthers blackish, heads 10 mm wide with 7-8 bracts
Known isolated population on lower slopes of Sumas Mtn. Inaccessible location on private property, but visible with a long lens (and a little imagination) from across the Sumas River near McDonald Park. Characteristic twisted branches visible, with a few light green leaves (of fresh summer second growth); Bigleaf Maple also visible below for comparison of scale. Can't distinguish from English Oak at this distance though of course.
A few plants in partial shade of Acer macrophyllum, stigmas 4-lobed, mixed with Epilobium ciliatum