Arrowroot
Thalia geniculata
Last reviewed: August 2026
Toxicity unknown
Arrowroot (Thalia geniculata) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.
Light
part sun
Water
high
Size
36"–96" H × 24"–48" W
Bloom
Jun, Jul, Aug, Sep, Oct
Native to
FL, LA
Pollinators
bees, butterflies
Before you buy
Your city may pay you to plant this
Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 437 programs across 44 states, each with a link to the provider and the date we last checked it.
Find rebates in your areaBrowse plants for this ecoregion
Thalia geniculata is a tall, striking aquatic perennial with large arrow-shaped leaves and purple flower spikes that bloom from summer through fall. This moisture-loving plant grows 3-8 feet tall and thrives in wet soils, making it ideal for rain gardens or pond edges. Its bold architectural form adds tropical flair to water features and boggy areas.
In an HOA neighborhood
Arrowroot takes more care to keep looking intentional in a front yard. Maintenance level: moderate. Consider it for backyard or mid-zone beds rather than the street edge.
Works well in: backyard only.
- Very tall growth may appear overgrown
- Requires consistently wet conditions
- Tropical appearance may seem too informal for front yards
Wildlife value
The long-blooming purple flowers attract bees and butterflies throughout the growing season. The dense growth provides shelter for wildlife in wetland garden settings.
Common questions
- How much sun does Arrowroot need?
- Arrowroot grows best in part sun conditions.
- When does Arrowroot bloom?
- Arrowroot blooms in June, July, August, September, and October.
- Where is Arrowroot native?
- Arrowroot (Thalia geniculata) is native to FL, LA, per vouchered herbarium specimen records and regional native plant society lists.
- What pollinators does Arrowroot attract?
- Arrowroot draws bees and butterflies.
- Is Arrowroot HOA-friendly?
- Arrowroot takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.
Native range data from vouchered herbarium specimen records and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
Ready to grow Arrowroot? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.
Not sure where to start? Take the 2-minute yard quiz