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Crotolaria

Crotalaria (kroh-tah-LAR-ee-ah)

Family: Fabaceae Native Herbaceous

Over 700 species of the genus Crotalaria or rattlebox exist worldwide, with the majority of them native to Africa, though there are some native to the United States. In their native habitat, they can be found in damp grasslands, floodplains, and along the edges of rivers, swamps, and other wet locations. Dry locations include roadsides and open fields. The common names all refer to the rattling sound made by the seeds inside the pod-like fruit when shaken. It was first introduced into the US as a soil builder, its nitrogen-fixing bacteria will improve the quality of the soil. Its botanical name comes from an Ancient Greek word that translates to castanet, again referring to the sound the dried seeds make. Depending on its location, it grows as an annual or perennial herb. It has alternate, simple, or divided leaves and yellow flowers on long terminal or axillary clusters, each being 5-parted and pea-like. The fruit is an inflated, subcylindric pod with many seeds. Native species include Crotalaria pumila and Crotalaria rotundifolia. This plant serves as a host to the Swallowtail butterfly ( Papilio glaucus ) , which is also referred to as a Tiger Butterfly. Insects, Diseases, and Other Plant Problems: The seeds from this plant are toxic to livestock. The self seeding by this plant can be weedy and aggressive in the surrounding locations.

Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 54 attributes.

How it fits the guild

Guild layer 4 - Herbaceous Optimal soil pH Acid (<6.0); Neutral (6.0-8.0)
See companions & conflicts ↓

Companions & Conflicts

Curated pairwise relationships between this plant and others in the library — who feeds whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.

No curated interactions recorded for this species yet.

Also noted by NC State

Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.

Full plant profile

Growing Conditions
Plant type
Annual; Herbaceous Perennial; Native Plant; Poisonous; Weed
Life cycle
Annual; Perennial
Light
Full sun (6 or more hours of direct sunlight a day)
Soil texture
Clay; High Organic Matter
Soil pH
Acid (<6.0); Neutral (6.0-8.0)
Soil drainage
Good Drainage | Moist | Occasionally Dry
Growth rate
Rapid
Maintenance
High
Canopy layer
4 - Herbaceous
Form & Appearance
Habit / form
Erect
Leaf color
Green
Leaf type
Compound (Pinnately , Bipinnately, Palmately); Simple
Leaf arrangement
Alternate
Leaf shape
Elliptical; Oblong
Hairs present
Yes
Leaf detail
Alternate, simple, or divided leaves
Flower color
Gold/Yellow
Flower value
Showy
Flower shape
Lipped
Flower detail
Yellow on long terminal or axillary clusters, each 5-parted and pea-likefus
Fruit color
Black; Brown/Copper
Fruit type
Legume
Fruit size
< 1 inch long, < 1 inch wide
Fruit detail
The fruits are an inflated, subcylindric pod with up to 20 seeds that rattle hence the common name.
Stem color
Green
Wildlife & Ecology
Native status
Native
Origin
Asia: Bangladesh; Bhutan; India; Tropics & Subtropics
Distribution
Tropical America and US
Wildlife value
Serves as a host plant for the larvae of several moths and butterflies.
Attracts
Butterflies; Moths
Play value
Attractive Flowers; Attracts Pollinators; Wildlife Larval Host
Food & Medicine
Fruit type
Legume

Uses (ethnobotany)

Weed

Landscape Use
Landscape theme
Native Garden
Garden tags
#poisonous #NC native #flowering #high maintenance #larval host plant #self-seeding #aggressive #fast growing #butterfly caterpillar host #moth caterpillar host #weedy
Problems & Resistance
Problems
Poisonous to Humans; Problem for Horses; Weedy
Resistant to
Drought; Heat; Poor Soil; Salt; Wet Soil
Propagation
Seed
Poison severity
Low
Poison parts
Leaves; Seeds
Poison symptoms
Toxic only if large quantities are eaten. Lower blood pressure and heart beat, stomach irritation.
Toxic principle
Alkaloids
Contact dermatitis
No
Toxicity summary
Low severity poison; parts: Leaves; Seeds

Planted at Hunnicutt

Nobody’s planted this one yet.