Caltha-Leaf Phacelia

phacelia calthifolia

The Caltha-Leaf Phacelia (Phacelia calthifolia) is a striking annual wildflower native to the arid desert regions of the southwestern United States, most famously coloring the gravelly washes and slopes of Death Valley and the Mojave Desert. Rising up in the wake of winter rains, this resilient plant plays a vital role in the brief spring ecology of the desert, providing abundant nectar for specialized native pollinators. It is particularly known for its intense violet-purple blooms and sticky, rounded leaves that heavily resemble marsh marigolds. However, despite its beauty, travelers must admire it from a distance, as the plant can cause severe skin irritation similar to poison oak.

Habitat: Found in dry, sandy or gravelly washes, canyon bottoms, and alluvial flats within Mojave Desert ecosystems below 1,500 meters.

Appearance

This erect, sticky-haired annual typically reaches heights of 10 to 30 centimeters. It features thick, rounded to heart-shaped dark green leaves with scalloped margins that grow along the reddish, glandular stems. The flowers are arranged in characteristic curled, scorpion-tail-like clusters (scorpioid cymes) that uncoil as they bloom. Each bell-shaped blossom is a deep, vivid royal purple to indigo, highlighted by bright, golden-yellow stamens protruding conspicuously from the center.

KingdomPlantaePhylumTracheophytaClassMagnoliopsidaOrderBoraginalesFamilyBoraginaceaeGenusPhacelia

Caltha-Leaf Phacelia

Interesting facts

During rare 'superbloom' events in Death Valley National Park, this species covers miles of dry, rocky ground in a sea of vibrant indigo.

Like poison oak, contact with this plant can cause a severe blistering skin rash on humans, earning it the colloquial nickname 'scorpion weed'.

The plant's scientific species name, calthifolia, literally translates to 'Caltha-leaved' due to the uncanny resemblance of its foliage to marsh marigolds.

Special abilities

The plant is covered in glandular hairs that exude sticky, oily secretions containing heptadecylcatechol, which causes a severe, itchy rash on herbivores and humans.

Its seeds possess a dormant protective coating that only breaks down after significant winter rainfall, ensuring the plant only grows when water is available.

Its flowering stalks slowly uncurl over several weeks, presenting a continuous sequence of fresh blooms to maximize pollination chances over a longer period.