[Onions: The Genus Allium East of the Cascade Mts. of Oregon and Washington]

Rock Onion

Allium macrum

Synonym: Allium equicaeleste

Rock Onion: Allium macrum (Synonym: Allium equicaeleste)

The photo above shows the form of rock onion, with a pair of basal leaves (which are beginning to whither by bloom time). Note that the leaves are u-shaped in cross-section, and that they are about equal in length to the scape, or slightly longer. Photographed on basalt outcrops near milepost 80 along Oregon Highway 19 east of Service Creek, OR..........April 8, 2007.

Close-up of a flower of Rock Onion: Allium macrum (Synonym: Allium equicaeleste) - Close-up of the inflorescence of Rock Onion: Allium macrum (Synonym: Allium equicaeleste)

The photo at left shows a fully opened flower of rock onion as photographed on basalt outcrops near milepost 80 along Oregon Highway 19 east of Service Creek, OR...........April 8, 2007. The stamens are about equal in length to the petals. The photo at right shows the orbicualr inflorescence of rock onion from the same location. Small rounded crests can be seen along the outer edge of the ovary.

Close-up of the tepals of Rock Onion: Allium macrum (Synonym: Allium equicaeleste) - Rock Onion: Allium macrum (Synonym: Allium equicaeleste)

The photo at left shows a close-up of the outer surface of a tepal of rock onion. Note the green stripe running the length of the tepal. Photographed on basalt outcrops near milepost 80 along Oregon Highway 19 east of Service Creek, OR...........April 8, 2007. The photo at right shows rock onion as seen with scalepod (Idahoa scapigera) on scablands near the old Cold Springs Guard Station to the east of Big Summit Prairie, Ochoco National Forest.

Rock Onion: Allium macrum (Synonym: Allium equicaeleste) - Rock Onion: Allium macrum (Synonym: Allium equicaeleste)

Rock onion blooming (left) at the Lawrence Memorial Grasslands several miles southwest of Shaniko, OR...........May 15, 2010. The photo at right shows rock onion at the beginning of its bloom period along Oregon Highway 206 several miles northwest of Condon, OR..........April 8, 2007.

Rock Onion: Allium macrum (Synonym: Allium equicaeleste) - Rock Onion: Allium macrum (Synonym: Allium equicaeleste) - Rock Onion: Allium macrum (Synonym: Allium equicaeleste)

Rock onion blooming on a vernally moist bald just north of the junction of Forest Roads 22 and 4210, Ochoco National Forest..........May 10, 2017.

Close-up of a flower of Rock Onion: Allium macrum (Synonym: Allium equicaeleste) - Close-up of the inflorescence of Rock Onion: Allium macrum (Synonym: Allium equicaeleste)

Photographed along Road K6000 near an elevation of 2780' on the southeast side of Mt. Adams..........May 22, 2005. Plants were just beginning to bloom on this date, and the outer surface of the tepals bears a central, greenish stripe. The scape is not flattened, and is about equal to or shorter than the two, channeled leaves. The stamnes are about equal to slightly longer than the tepals.

Inflorescence of Rock Onion: Allium macrum (Synonym: Allium equicaeleste) - Rock Onion: Allium macrum (Synonym: Allium equicaeleste)

Rock onion blooming amongst Sandberg's bluegrass along the Bickleton Highway at a pass near milepost 18 between Bickleton, WA and Mabton, WA...........April 23, 2013.

Rock Onion: Allium macrum (Synonym: Allium equicaeleste) - A close-up image of the inflorescence of Rock Onion: Allium macrum (Synonym: Allium equicaeleste)

Rock onions blooming on vernally moist scablands near the end of Forest Road 4240, Ochoco National Forest........April 26, 2018.

Rock Onion: Allium macrum (Synonym: Allium equicaeleste) - Rock Onion: Allium macrum (Synonym: Allium equicaeleste)

Rock Onion: Allium macrum (Synonym: Allium equicaeleste) - Rock Onion: Allium macrum (Synonym: Allium equicaeleste)

Rock onion fading out of bloom on scablands between Long Prairie and FS Road 4230-050, Ochoco National Forest........April 30, 2016.

Paul Slichter