[Rockcresses: The Genera Arabis, Boechera and Turritis East of the Cascade Mountains of Oregon and Washington]
Holboell's Rockcress, Reflexed Rockcress, Secund Rockcress
Boechera retrofracta
Synonyms: Arabis holboellii, Arabis holboellii var. retrofracta, Arabis holboellii var. secunda, Arabis retrofracta, Arabis secunda, Boechera holbellii, Bochera hoboellii var. secunda
The photo above shows a close-up view of the flowers
of Holboell's rockcress (variety retrofracta) as seen along FS Rd 4650
to the east of Table Rock in the northern Wallowa-Whitman NF.........June 26, 2008. Note the numerous starlike hairs (many held aloft by short hairs) on the calyx lobes.
The
photo at right shows the leaves and stems of Holboell's rockcress (variety
retrofracta)
as seen along FS Rd 21 above Murderers Creek, Malheur NF........5/24/2003.
Characteristics:
Holboell's rockcress is a biennial or short-lived perennial
wildflower. One to several simple (to branched above) stems arise to a height
of 100 cm. The lower part of the plant is strongly haired with simple or radially
branched hairs, while the herbage is smooth to uniformly hairy above. The basal
leaves are typically arranged in a basal rosette of linear-oblanceolate to broad,
oblanceolate-spatulate leaves which are 1-5.5 cm long and 2-7 mm wide. The
blades range from entire to toothed and are typically covered with fine felt-like
hairs or longer, coarse or fine hairs. The numerous stem leaves often overlap
each other and are often petiolate, although the upper leaves on some varieties
are clasping with heart-shaped bases. They range from lanceolate to narrowly
oblanceolate in shape and 1-5 cm long and 2-7 mm wide. Their blades are typically
pubescent although they may be glabrous on some varieties.
The inflorescence is a densely-flowered raceme of 20-100 white,
pink or most commonly, pinkish-purple flowers. The pedicels are 5-15 mm long
and either uniformly curved downwards or more commonly abruptly bent downwards
at the base. The pedicels vary from glabrous to hairy. Each of the 4 sepals
is glabrous to hairy and each is 2.5-5 mm long. Each of the 4 petals is 5-10
mm long. The fruits are glabrous siliques from 3-7 cm long and 1-2 mm wide.
Variety retrofracta has simple to branched stems above
measuring 20-90 cm high. They have woolly-haired stems below and range from
pubescent to nearly glabrous above. The basal leaves are greater than 3 mm wide
with entire to toothed margins. The leaf margins of the stem leaves are noticeably
rolled under. The pedicels are sharply bent downwards
at their bases.
Varieties:
Variety collinsii: Stem leaves with heart-shaped
bases that often clasp the stem. Petals less than 7 mm long. Pedicels bent sharply
downwards at their base. The siliques are more or less straight. Found from
Washington to Alberta, Wyoming and east through he Dakotas and Manitoba to Quebec.
Variety pendulocarpa:
Stem leaves lack heart-shaped bases. Found from British
Columbia south to California and east to Montana and Colorado.
Variety pinetorum: Stem
leaves with heart-shaped bases that often clasp the stem. Basal leaves are coarsely
hairy. Pedicels uniformly curved outwards and downwards, not sharply reflexed
downwards at the base. The siliques are thus spreading-drooping with the tip
often incurved. Found from British Columbia south to California and east to
Saskatchewan and Colorado.
Variety retrofracta: Stem
leaves with heart-shaped bases that often clasp the stem. Leaves with margins
rolled under, the upper ones pubescent. The basal leaves are covered in short,
dense, felt-like hairs. Pedicels bent sharply downwards at their base. Petals
over 7 mm long. Siliques 1.5-2 mm wide and more or less straight. Found from
the Yukon and British Columbia south to California and east to Alberta (and
occasionally to Quebec) and Colorado.
Habitat:
Hairy rockcress is found in forests and forest openings at all
elevations.
Range:
Hairy rockcress is found from the Arctic south through much
of North America to California, Arizona, and New Mexico, and as far east as
the mid-Atlantic states.
Secund rockcress observed on the hilltop above the Pine Mountain Observatory, Deschutes National Forest......May 12, 2018.
This possibly may be Boechera puberula with its numerous, overlapping stem leaves?.
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Secund rockcress observed
observed along
the Fremont National Recreation Trail #160 on the west side of Twelvemile Peak, Fremont-Winema National Forest......July 16, 2022.
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Secund rockcress as seen along the Sprague Highway about one mile west of the junction with Miller Ranch Road, eastern Washington...........April 28, 2014.
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Secund rockcress blooming atop Bickleton Ridge in the Bickleton Ridge Unit of the Klickitat Wildlife Area.........May 7, 2017.
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What appears to be Boechera retrofracta in bloom along Forest Service Road 35 on Table Mountain, Wenatchee National Forest........June 4, 2013.
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The photo above shows a close-up view of the inflorescence and upper stem leaves
of Holboell's rockcress (variety retrofracta) as seen along FS Rd 4650
to the east of Table Rock in the northern Wallowa-Whitman NF.......June 26, 2008.
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Close-ups of the inflorescence of Holboell's rock cress (var. retrofracta). Note the glabrous, spreading to reflexed pedicels and the numerous star-shaped hairs on the calyces. Photographed on Wedge Mt., Wenatchee National Forest.......June 8, 2009.
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Additional close-up views of Holboell's rockcress as seen at the Lawrence Memorial Grasslands several miles south of Shaniko, OR.........May 15, 2010.
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Holboell's rockcress (var. retrofracta) as seen in scablands at the northeast corner of the junction of FS Roads #42 and #3010, southeast corner of Big Summit Prairie, Ochoco National Forest..........April 29, 2016.
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Holboell's rockcress (var. retrofracta) as seen in scablands near the junction of FS Roads #42 and #300, Ochoco National Forest and adjacent BLM lands..........April 30, 2016.
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Holboell's rockcress (var. retrofracta) as seen on Bald Butte which is located about 8-10 miles north of Gearhart Mountain, Fremont-Winema National Forest........June 19, 2020.
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Reflexed rockcress as seen along the Wapaloosie Mountain Trail #15 in the Kettle Range, Colville National Forest.........June 23, 2016.
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Close-up images of the rolled stem leaf margins and sharply reflexed flowers of reflexed rockcress as seen in scablands along Forest Road 30 at the east side of Big Summit Prairie, Ochoco National Forest.........May 19, 2017.
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Reflexed rockcress observed along the Fremont National Recreation Trail on the northwestern slopes of Hager Mountain, Fremont-Winema National Forest.......June 18, 2020.
The photo above shows the basal leaves and lower stem leaves
of Holboell's rockcress (variety retrofracta) as seen along FS Rd 21
above Murderers Creek, Malheur NF........5/24/2003.
Paul Slichter