Native Plants

Merckia

Wilhelmsia physodes

USDA symbol: WIPH

perennial forb

Alaska: native
Canada: native

If you’re looking for a truly unique native plant that can handle the harshest conditions North America has to offer, let me introduce you to merckia (Wilhelmsia physodes). This little-known perennial forb might just be the conversation starter your specialized garden needs – though it’s definitely not for every gardener ...

Merckia: A Hardy Arctic Native for Specialized Gardens

If you’re looking for a truly unique native plant that can handle the harshest conditions North America has to offer, let me introduce you to merckia (Wilhelmsia physodes). This little-known perennial forb might just be the conversation starter your specialized garden needs – though it’s definitely not for every gardener or every climate!

What is Merckia?

Merckia is a perennial forb, which simply means it’s an herbaceous plant that comes back year after year without developing woody stems like shrubs or trees. You might also see this plant referred to by its synonyms Arenaria physodes or Merckia physodes in older botanical references, but Wilhelmsia physodes is the current accepted name.

As a forb, merckia produces its growing buds at or below ground level, helping it survive in some pretty tough conditions. This survival strategy makes perfect sense when you learn where this hardy little plant calls home.

Where Does Merckia Grow Naturally?

Merckia is a true North American native with an impressively cold-hardy range. You’ll find this species growing naturally in Alaska, Yukon, and the Northwest Territories of Canada. This is definitely a plant that has evolved to handle serious winter conditions!

  • Species observed
  • No observations

Should You Plant Merckia in Your Garden?

Here’s where things get interesting – and a bit challenging. Merckia is classified as a facultative wetland plant in Alaska, meaning it can grow in both wet and drier conditions. However, there are several factors to consider before adding this plant to your garden:

The Good News:

  • It’s a native species, so you’re supporting local ecosystems
  • Extremely cold hardy – perfect for northern gardeners
  • Flexible about moisture conditions
  • Unique conversation piece for specialized native plant gardens

The Challenges:

  • Very limited availability in the nursery trade
  • Specific climate requirements (likely USDA zones 1-3)
  • Little information available about cultivation practices
  • May not thrive in warmer climates

Who Should Consider Growing Merckia?

This plant is best suited for dedicated native plant enthusiasts in very cold climates who are interested in preserving and showcasing rare native species. If you’re gardening in Alaska, northern Canada, or similar extreme northern climates, and you have access to responsibly sourced plants or seeds, merckia could be a fascinating addition to a specialized native plant collection.

However, if you’re in more temperate zones or looking for easy-care garden plants, you might want to explore other native options that are better suited to cultivation and more readily available.

Growing Conditions and Care

Given merckia’s natural habitat, this plant likely prefers:

  • Cold climates with long, harsh winters
  • Well-draining to occasionally moist soils
  • Full sun to partial shade conditions
  • Minimal summer heat

Unfortunately, detailed cultivation information for merckia is quite limited, which reflects how rarely this species is grown in gardens. If you’re determined to try growing it, your best bet would be to mimic its natural growing conditions as closely as possible.

The Bottom Line

Merckia is a fascinating native plant that showcases the incredible adaptability of North American flora to extreme conditions. While it’s not a plant for every garden or every gardener, it represents an important part of our northern ecosystems and could be a rewarding challenge for specialized native plant enthusiasts in appropriate climates.

If you’re in a warmer climate or looking for more readily available native plants, consider exploring other native forbs and wildflowers that are better suited to cultivation and more widely available through native plant nurseries in your region.

Wilhelmsia physodes 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. Wilhelmsia physodes is also known as:

Arenaria physodes ex | USDA symbol: ARPH
Merckia physodes & | USDA symbol: MEPH

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

Alaska ()

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: Caryophyllidae
Order: Caryophyllales
Family: Caryophyllaceae Juss. - Pink family
Genus: Wilhelmsia Rchb. - wilhelmsia

Species: Wilhelmsia physodes (Fisch. ex Ser.) McNeill - merckia

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