North America Native Plant

Tucson Mountain Spiderling

Botanical name: Boerhavia megaptera

USDA symbol: BOME

Life cycle: annual

Habit: forb

Native status: Native to the lower 48 states  

Tucson Mountain Spiderling: A Rare Desert Gem Worth Protecting Meet the Tucson Mountain spiderling (Boerhavia megaptera), a charming little annual that’s as rare as it is resilient. This petite desert wildflower might not win any size contests, but what it lacks in stature, it makes up for in ecological importance ...

Rare plant alert!

Region: Conservation status by state

Status: S3: Status is uncertain but is somewhere between the following rankings: Vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals ⚘

Tucson Mountain Spiderling: A Rare Desert Gem Worth Protecting

Meet the Tucson Mountain spiderling (Boerhavia megaptera), a charming little annual that’s as rare as it is resilient. This petite desert wildflower might not win any size contests, but what it lacks in stature, it makes up for in ecological importance and quiet beauty.

What Makes This Plant Special?

The Tucson Mountain spiderling is a true Arizona native, calling the Sonoran Desert home. As an annual plant, it completes its entire life cycle in just one growing season, making the most of favorable conditions when they arrive. Don’t let its delicate appearance fool you – this little survivor has adapted perfectly to one of North America’s most challenging environments.

Where You’ll Find It Growing Wild

This desert specialist is found exclusively in Arizona, where it has carved out its niche in the rugged landscapes around Tucson and the surrounding mountain ranges. It’s perfectly adapted to the unique conditions of the Sonoran Desert region.

A Conservation Concern

Here’s where things get serious: the Tucson Mountain spiderling has a Global Conservation Status of S3, meaning it’s considered vulnerable. With only 21 to 100 known occurrences and an estimated 3,000 to 10,000 individuals in the wild, this little plant needs our help. Its rarity makes it vulnerable to habitat loss and other environmental pressures.

Should You Grow Tucson Mountain Spiderling?

If you’re passionate about desert gardening and native plant conservation, this species could be a meaningful addition to your landscape – but only if you can source it responsibly. Given its vulnerable status, it’s crucial that any plants or seeds come from ethical suppliers who don’t collect from wild populations.

Garden Role and Design Uses

In the right setting, Tucson Mountain spiderling can serve as:

  • A delicate ground cover in desert wildflower gardens
  • An educational specimen in native plant collections
  • A conversation starter about desert plant conservation
  • Part of a authentic Sonoran Desert landscape

Growing Conditions and Care

This desert native thrives in conditions that would challenge many other plants:

  • Sunlight: Full sun exposure
  • Soil: Well-draining, sandy or rocky desert soil
  • Water: Minimal irrigation; relies primarily on natural rainfall
  • Climate: USDA hardiness zones 9b-11

Planting and Care Tips

Growing Tucson Mountain spiderling successfully means mimicking its natural desert habitat:

  • Direct seed in fall when temperatures begin to cool
  • Ensure excellent drainage to prevent root rot
  • Avoid overwatering – this plant is built for drought
  • Allow natural rainfall to provide most moisture needs
  • Be patient – germination occurs when conditions are just right

Benefits for Pollinators and Wildlife

While small, the tiny pink to white flowers of Tucson Mountain spiderling provide nectar for small native bees and other beneficial insects. Every native plant, no matter how modest, plays a role in supporting local ecosystems.

The Bottom Line

Tucson Mountain spiderling represents both an opportunity and a responsibility. If you have the right growing conditions and can source plants or seeds ethically, growing this rare native can be a meaningful way to support desert plant conservation. However, its vulnerable status means we must be thoughtful gardeners, ensuring our enthusiasm for native plants doesn’t inadvertently harm wild populations.

Consider this charming desert annual not just as a garden plant, but as a living reminder of the precious biodiversity that makes the American Southwest so unique. With careful cultivation and responsible sourcing, we can help ensure that future generations will be able to appreciate the quiet beauty of the Tucson Mountain spiderling.

Tucson Mountain Spiderling

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Caryophyllidae

Order

Caryophyllales

Family

Nyctaginaceae Juss. - Four o'clock family

Genus

Boerhavia L. - spiderling

Species

Boerhavia megaptera Standl. - Tucson Mountain spiderling

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