Non-native Plants

Branched Porterweed

Stachytarpheta australis

USDA symbol: STAU

annual subshrub

Hawaii: non-native, naturalized

If you’ve been wandering around Hawaiian gardens and spotted a small flowering herb that seems to pop up in various spots, you might have encountered branched porterweed (Stachytarpheta australis). This unassuming little plant has quietly made itself at home in the islands, though it’s not originally from there. Branched porterweed ...

Branched Porterweed: A Lesser-Known Hawaiian Garden Resident

If you’ve been wandering around Hawaiian gardens and spotted a small flowering herb that seems to pop up in various spots, you might have encountered branched porterweed (Stachytarpheta australis). This unassuming little plant has quietly made itself at home in the islands, though it’s not originally from there.

What Exactly Is Branched Porterweed?

Branched porterweed is a non-native herb that belongs to the verbena family. Unlike its more famous cousin, blue porterweed, this species tends to fly under the radar. It’s what botanists call a forb – essentially a flowering plant that doesn’t develop woody stems like shrubs or trees. Think of it as nature’s version of a perennial flower that keeps things simple.

This adaptable little plant can behave as either an annual or perennial, depending on growing conditions. It produces small flowers and has a branching growth pattern that gives it its common name.

Where You’ll Find It

Currently, branched porterweed has established itself in Hawaii, where it reproduces on its own without human intervention. It’s managed to adapt well to island life, though we don’t have detailed information about exactly which Hawaiian islands it calls home.

  • Species observed
  • No observations

The Garden Reality Check

Here’s where things get a bit tricky for gardeners. While branched porterweed isn’t currently listed as invasive or noxious, we simply don’t have enough research about its long-term impact on Hawaiian ecosystems. It’s one of those plants that exists in a gray area – not necessarily harmful, but not necessarily beneficial either.

The plant does have some interesting characteristics that might appeal to gardeners:

  • It’s adaptable to both wet and dry conditions (facultative wetland status)
  • It can handle various growing environments
  • It doesn’t require intensive maintenance

Growing Considerations

If you’re thinking about branched porterweed for your garden, here’s what we know: it’s fairly tolerant of different moisture levels, which makes it relatively low-maintenance. However, specific information about soil preferences, sunlight needs, and care requirements is limited for this particular species.

Since it can function in both wetland and non-wetland environments, it’s likely quite adaptable to various garden situations. But without detailed growing guides, you’d essentially be experimenting.

A Better Alternative: Go Native

Given the limited information about branched porterweed and its non-native status, Hawaiian gardeners might want to consider native alternatives that provide similar benefits with known ecological value. Native Hawaiian plants are adapted to local conditions, support native wildlife, and help preserve the islands’ unique ecosystem.

Some native options to explore include native Hawaiian sedges, grasses, or other herbaceous plants that naturally occur in similar habitats.

The Bottom Line

Branched porterweed represents one of those garden mysteries – a plant that’s present but not well-documented in terms of its garden potential or ecological impact. While it’s not flagged as problematic, the lack of detailed information makes it difficult to recommend confidently.

For Hawaiian gardeners, focusing on well-researched native plants or non-native species with known benefits might be a more reliable path to garden success. If you do encounter branched porterweed in your garden, it’s probably not cause for alarm, but it’s also not necessarily something to actively cultivate.

Sometimes the most interesting garden stories are about the plants we choose not to grow, leaving space instead for species that we know will thrive and contribute positively to our local environment.

Stachytarpheta australis is also known as...

Often we refer to plants by their common names. When shopping for plants the scientific name is the best way to positively identify the plant species you desire. But some plants have more than one name! While it doesn't happen often, nurseries might display one name while you're searching for another. Stachytarpheta australis is also known as:

Stachytarpheta dichotoma auct. non | USDA symbol: STDI13

Why do some plants have more than one name? Over time plant species may be renamed for a few reasons:

  1. Botanists in different regions named the same plant without knowing it had already been classified.
  2. A species was reclassified after scientific advances in, for example, DNA analysis.
  3. Slight variations within a species are sometimes mistakenly identified as entirely new species.

Wetland Status

The rule of seasoned gardeners and landscapers is to choose the "right plant for the right place" — matching plants to their ideal growing conditions, so they'll thrive with less care and fewer inputs. But the simplicity of this catchphrase conceals how tricky plant selection can be if you don't have the right information. While tags on nursery plants list watering requirements, there's more to the story.

Knowing a plant's wetland status can simplify the process by revealing the interaction between plants, water, and soil. You might be surprised to learn that popular landscape plants are wetland species! And what may be a wetland plant in one area, in another it might thrive in drier conditions. The table below gives insight into the preferred growing conditions of this plant throughout its geographical distribution.

Region
Preferred Habitat

Hawaii ()

Facultative
Wetland Glossary
Obligate Wetland
Facultative Wetland
Facultative
Facultative Upland
Obligate Upland
Almost always occurs in wetlands
Usually occurs in wetlands but may occur in non-wetlands
Can occur in wetlands and non-wetlands
Usually occurs in non-wetlands but may occur in wetlands
Almost never occurs in wetlands

Classification

Group: Dicot
Kingdom: Plantae - Plants
Subkingdom: Tracheobionta - Vascular plants
Superdivision: Spermatophyta - Seed plants
Division: Magnoliophyta - Flowering plants
Class: Magnoliopsida - Dicotyledons
Subclass: Asteridae
Order: Lamiales
Family: Verbenaceae J. St.-Hil. - Verbena family
Genus: Stachytarpheta Vahl - porterweed

Species: Stachytarpheta australis Moldenke - branched porterweed

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