Senna roemeriana
two-leaved senna
South-central US and northern Mexico
Attracts PollinatorsAttracts ButterfliesDeer ResistantDrought TolerantContainer Friendly
Native to North America
Overview
Senna roemeriana is a clump-forming herbaceous perennial reaching 1-2 feet (30-60 cm) tall and about as wide, growing from a woody root crown. The slender green stems carry compound leaves each divided into a single pair of narrow, pointed leaflets 1-2 inches (2.5-5 cm) long, a feature that gives the plant its common name. Bright yellow five-petaled flowers about 1 inch (2.5 cm) across open in loose clusters at the stem tips, with brown anthers at the center. Flowering runs from April to October, heaviest after rain. Flat, curved seedpods 1-2 inches (2.5-5 cm) long follow, green ripening to brown and splitting to release flat seeds. The species grows on dry limestone soils and rocky slopes and tolerates heat and drought once established. The foliage contains compounds that can poison livestock if grazed heavily. Plants are short-lived, often persisting three to five years, but self-sow where soil stays open. It serves as a larval host for several sulphur butterflies.
Native Range
Senna roemeriana is native to the south-central United States and northern Mexico, from Texas and Oklahoma west to New Mexico. It grows on dry limestone hills, rocky prairies, and roadsides, mostly on alkaline soils.Suggested Uses
Used in xeriscape and rock gardens, native plantings, and pollinator borders on alkaline soils, spaced 18-24 inches (45-60 cm) apart. It supports sulphur butterfly larvae and native bees through a long bloom season. Suited to dry slopes where richer plantings fail.How to Identify
Appearance
Size & Dimensions
Height1' - 2'
Width/Spread1' - 2'
Reaches mature size in approximately 1 years
Bloom Information
Detailed Descriptions
Foliage Description
Green to 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
Grow Senna roemeriana in full sun on dry, well-drained alkaline soils, where it withstands heat, drought, and rocky ground. It needs little water once established and declines in wet or heavy clay soils. Plants reach full size in a single season and reseed readily where bare soil is available. A pH from 7.0 to 8.5 suits it, matching its limestone habitat. Cutting plants back after the first bloom flush encourages a second round of flowers. Overwatering and shade produce weak, sprawling growth.Pruning
Shearing plants by about one-third after the first heavy bloom prompts rebloom and keeps the form compact. Spent stems are removed in late fall or early spring. No other pruning is needed for this short-lived perennial.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
fallearly spring
Container Growing
✓ Suitable for container growing
Minimum container size: 3 gallons