North America Native Plant

Coamo

Botanical name: Oxalis rugeliana

USDA symbol: OXRU2

Life cycle: perennial

Habit: forb

Native status: Native to Puerto Rico  

Synonyms: Oxalis domingensis Urb. (OXDO)   

Coamo: A Lesser-Known Puerto Rican Native Worth Learning About Meet Coamo (Oxalis rugeliana), a native Puerto Rican plant that’s definitely flying under the radar in most gardening circles. If you’re scratching your head wondering why you’ve never heard of this one, you’re not alone – this little forb isn’t exactly ...

Coamo: A Lesser-Known Puerto Rican Native Worth Learning About

Meet Coamo (Oxalis rugeliana), a native Puerto Rican plant that’s definitely flying under the radar in most gardening circles. If you’re scratching your head wondering why you’ve never heard of this one, you’re not alone – this little forb isn’t exactly making headlines in the gardening world, but that doesn’t mean it’s not worth knowing about.

What Exactly Is Coamo?

Coamo belongs to the wood sorrel family and is scientifically known as Oxalis rugeliana. You might also see it referenced by its botanical synonym Oxalis domingensis. As a perennial forb, this plant lacks the woody stems you’d find on shrubs or trees, instead producing soft, herbaceous growth that emerges from buds at or below ground level each growing season.

Where Does Coamo Call Home?

This plant is a true Puerto Rican native – born and raised on the island, so to speak. Its natural range is limited to Puerto Rico, making it an endemic species that’s evolved specifically to thrive in the island’s unique climate and growing conditions.

The Reality Check: What We Don’t Know

Here’s where things get a bit tricky – and honestly, pretty frustrating for curious gardeners. Despite being a native species, there’s surprisingly little documented information about Coamo’s specific growing requirements, appearance, or garden potential. We don’t have clear details about:

  • Its exact size and growth habit
  • Preferred soil conditions and moisture requirements
  • Flowering characteristics or seasonal interest
  • Pollinator relationships or wildlife benefits
  • Propagation methods or cultivation techniques
  • Appropriate USDA hardiness zones for cultivation outside Puerto Rico

Should You Try Growing Coamo?

If you’re gardening in Puerto Rico, Coamo could potentially be a fantastic addition to a native plant garden – after all, it’s naturally adapted to your local conditions. However, the lack of cultivation information means you’d be somewhat pioneering in your gardening efforts.

For gardeners outside Puerto Rico, the limited information makes it difficult to recommend this plant with confidence. Without knowing its cold tolerance, soil preferences, or basic care requirements, successful cultivation would be quite challenging.

The Native Plant Advantage

What we do know is that native plants like Coamo offer inherent benefits when grown in their natural range. They’re typically:

  • Better adapted to local climate conditions
  • More resistant to regional pests and diseases
  • Supportive of local ecosystems and wildlife
  • Lower maintenance once established

Moving Forward with Coamo

If you’re intrigued by this Puerto Rican native, your best bet is to connect with local botanical gardens, native plant societies, or university extension services in Puerto Rico. They may have additional insights about this species that haven’t made it into widely available botanical literature.

For gardeners interested in wood sorrels but living outside Puerto Rico, consider researching Oxalis species native to your own region – you’ll likely find better-documented options that can provide similar ecological benefits in your local landscape.

Sometimes the most interesting plants are the ones we know the least about – they remind us that there’s still so much to discover in the plant world, even in our own backyards.

Coamo

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Rosidae

Order

Geraniales

Family

Oxalidaceae R. Br. - Wood-Sorrel family

Genus

Oxalis L. - woodsorrel

Species

Oxalis rugeliana Urb. - coamo

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA