Common Names: Mat Rock Spiraea, Mat Rockspirea, Rocky Mountain Rockmat, Dwarf Spiraea, Petrophytum, Tufted Rockmat
Synonyms: Petrophytum caespitosum, orth. var. Petrophyton caespitosum
Taxonomy: Rose (Rosaceae)
Habit: Perennial Forb, Herb
Size: up to 8”
Flowers: White
Bloom: May, Jun, Jul, Aug, Sep, Oct
Leaves:
Fruit: Aggregated follicles
Description:
The plant often grows on vertical surfaces and hangs by its roots, which cling to cracks in rock. The stems are thick and very short, covered densely in rosettes of oval leaves. Both surfaces of the leaves are lightly covered in short fine hairs, which may not be obvious without close inspection. It produces many inflorescences which are spikelike clusters of flowers arising on erect peduncles up to 4” (10 cm) tall. Each inflorescence is packed with flowers, each with five tiny white petals, many whiskery stamens, and usually 5 hairy pistils. The flower parts dry and may fall away, leaving a cluster of developing fruits, follicles containing the seeds.
Distribution: AZ, CA, CO, ID, MT, NM, NV, OR, SD, TX, UT, WY
Seen: Las Vegas
Habitat: Granite or limestone rock crevices from foothills to alpine summits
