Mentzelia laevicaulis
giant blazingstar
Overview
Mentzelia laevicaulis is a biennial to short-lived perennial 1-3.5 feet (30-105 cm) tall, with stout, smooth, whitish stems branching toward the top. Leaves are lance-shaped, 2-6 inches (5-15 cm) long, with coarsely toothed margins and a rough, sandpapery surface from barbed hairs that cling to clothing and fur. Star-shaped yellow flowers 2-5 inches (5-13 cm) across carry five pointed petals and a dense central tuft of many long stamens. The flowers open in late afternoon and close by the following midday, blooming from June to September. After flowering, cylindrical capsules form and release flat seeds. The plant grows from a deep taproot and tolerates dry, disturbed ground. Stems and leaves are pale gray-green. In its first year it forms a low rosette, flowering in later years before dying. Plants appear scattered rather than in dense stands.
Native Range
Native to western North America from British Columbia south to California and east to the Rocky Mountains. Grows in dry, open, disturbed ground, gravelly washes, roadsides, and rocky slopes in well-drained soils from low elevations to about 9,000 feet (2,700 m).Suggested Uses
Grown in desert, gravel, and dryland native plantings and on dry banks, spaced 12-24 inches (30-60 cm) apart. The large evening flowers are visited by native bees. The barbed, clinging foliage and biennial habit make it unsuited to high-traffic borders.How to Identify
Appearance
Size & Dimensions
Height1' - 3'6"
Width/Spread1' - 2'
Reaches mature size in approximately 3 years
Bloom Information
Flowers from June to September, opening in late afternoon and closing by the next midday. Each flower lasts about one day, and a plant produces new flowers in succession over 6-10 weeks. Bloom is heaviest in mid to late summer and depends on spring and early-summer moisture.
Detailed Descriptions
Foliage Description
gray-greenGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Grows in full sun in sandy, gravelly, or rocky, sharply drained soil of low fertility. Water sparingly; established plants draw on a deep taproot and tolerate drought, declining in rich or wet ground. Alkaline and neutral soils both suit it. The deep taproot makes transplanting difficult, so plants are usually grown from seed sown in place. Rich or irrigated soil shortens the plant''s life. Few pests affect it in dry conditions.Pruning
Cut the dead flowering stem to the ground after seed drop. Removing capsules before they open limits self-seeding. No other pruning is needed during the plant''s short life.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
fall