# mat rock spiraea (*Petrophytum caespitosum*)

Mat rock spiraea is a small, beautiful shrub that grows in rocky places. Its tiny flowers bloom in clusters, making it a lovely sight in nature.

- **Category:** [Plants](https://www.snappit.app/explore/categories/plant)
- **Rarity:** Common
- **Danger:** 1/5 · Very low
- **Snaps:** 2
- **Habitat:** Mountain regions

![mat rock spiraea](https://commons.wikimedia.org/w/index.php?title=Special:Redirect/file/Petrophyton_caespitosum_ssp_caespitosum_4.jpg&width=800)

Photo: Stan Shebs, CC BY-SA 3.0 · [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Petrophyton_caespitosum_ssp_caespitosum_4.jpg)

## Appearance

The mat rock spiraea is a low-growing subshrub, forming dense, compact mats with small, oval, sage-green leaves. It produces abundant clusters of tiny, five-petaled white or pale pink flowers, which create a delicate contrast against its harsh, rocky habitat.

## Taxonomy

- **Kingdom:** Plantae
- **Phylum:** Tracheophyta
- **Class:** Magnoliopsida
- **Order:** Rosales
- **Family:** Rosaceae
- **Genus:** Petrophytum

## Interesting facts

- Despite its small size, some mat rock spiraea plants can live for over 100 years.
- Its scientific name, \*Petrophytum\*, actually means 'rock plant' in Greek!
- This amazing plant can grow directly out of cracks in solid rock with almost no soil!
- Tiny bees and butterflies visit these tough plants, even on windy mountain cliffs.

## Special abilities

- **Rock Anchor:** Mat rock spiraea has an extensive, deep root system that can penetrate tiny rock crevices, anchoring it securely against strong winds and erosion.
- **Extreme Shield:** This spiraea grows in a tight, cushion-like form, which helps it withstand severe temperatures and powerful winds on exposed mountain slopes.
- **Drought Fighter:** It has small, thick, often hairy leaves that are adapted to minimize water loss, allowing the plant to thrive in very dry, rocky environments.

## Measurements & details

- **Height:** 10-30 cm
- **Flower Size:** 0.3-0.5 cm
- **Bloom Season:** Summer
- **Edible:** No
- **Toxicity:** None
- **Lifecycle:** Perennial
- **Pollination Method:** Insect
- **Cmc:** 30-60 C

## Ecological connections

- **Pollinates:** European honey bee (*Apis mellifera*) — Visits flowers for nectar.
- **Pollinates:** Two-form bumble bee (*Bombus bifarius*) — Active pollinator in alpine areas.
- **Pollinates:** Painted Lady butterfly (*Vanessa cardui*) — Sips nectar from blossoms.

## Traits

- [Deciduous](https://www.snappit.app/explore/traits/deciduous): Deciduous plants periodically shed all their leaves, typically during autumn or dry seasons.
- [Flowering](https://www.snappit.app/explore/traits/flowering): Flowering plants are any plants that produce flowers as part of their reproductive cycle.
- [Cluster Flower](https://www.snappit.app/explore/traits/cluster-flower): Cluster flowers are inflorescences where individual flowers are arranged closely together on a common stem.
- [Shrub](https://www.snappit.app/explore/traits/shrub): A shrub is a woody plant smaller than a tree, typically with multiple stems branching from or near the ground.
- [Colorful](https://www.snappit.app/explore/traits/colorful): Colorful describes organisms or objects displaying a wide range of bright and distinct colors.
- [Pollinator Magnet](https://www.snappit.app/explore/traits/pollinator-magnet): Describes plants that are particularly attractive and beneficial to a wide range of pollinating organisms.
- [Mountain](https://www.snappit.app/explore/traits/mountain): This habitat trait identifies species found in mountainous regions, characterized by high elevation, steep slopes, and varying climate zones.

## Collections

- [Plants](https://www.snappit.app/explore/collections/plants)

## Safety

**Danger:** 1/5 · Very low

Always look but don't touch plants unless you know they are safe.

## Frequently Asked Questions

### How to identify mat rock spiraea?

Start with the whole plant, then compare leaf arrangement, leaf edges, stems and any flowers or fruit. Opposite leaves grow in pairs; alternate leaves come one at a time along the stem. These details tell you far more together than a single green leaf does. Plant Identifier: upload a photo and compare the visible details.

### How tall is mat rock spiraea?

10-30 cm

### How big are the flowers on mat rock spiraea?

0.3-0.5 cm

### When does mat rock spiraea bloom?

Summer

### Is mat rock spiraea edible?

No

### Is mat rock spiraea toxic?

None

### What is mat rock spiraea's lifecycle?

Perennial

### How is mat rock spiraea pollinated?

Insect

## Where to spot

- [Bighorn Canyon National Recreation Area](https://www.snappit.app/guides/places/bighorn-canyon-national-recreation-area) — Montana, US · National Park
- [Walnut Canyon National Monument](https://www.snappit.app/guides/places/walnut-canyon-national-monument) — Arizona, US · National Park
- [Zion Lodge–Birch Creek Historic District](https://www.snappit.app/guides/places/zion-lodge-birch-creek-historic-district) — Utah, US · Historic District

[View all places to see mat rock spiraea](https://www.snappit.app/guides/where-to-see/mat-rock-spiraea)

## More Plants

- [white snakeroot](https://www.snappit.app/explore/white-snakeroot) (*Ageratina altissima*)
- [tree-of-heaven](https://www.snappit.app/explore/tree-of-heaven) (*Ailanthus altissima*)
- [western sword fern](https://www.snappit.app/explore/western-sword-fern) (*Polystichum munitum*)
- [common milkweed](https://www.snappit.app/explore/common-milkweed) (*Asclepias syriaca*)

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Source: [Mat Rock Spiraea: Facts & Places to See — Snappit](https://www.snappit.app/explore/mat-rock-spiraea)