Aphyllon validum subsp. howellii
Howell's broomrape, Howell's Broomrape, Howell's broomrape
Photo: parent species Aphyllon validum · Photo by Chez Brungraber
Family: Orobanchaceae · Type: Herb · Native
Conservation status: CNPS 4.3
Aphyllon validum subsp. howellii (Howell's broomrape) is a native California herb in the Orobanchaceae family, recognized by slender stem enlarged at base, volcanic/serpentine soils, 6-20 cm.
Howell's broomrape is a rare (CNPS 4.3) California native perennial found in volcanic and serpentine landscapes of California in open chaparral at elevations of 200 to 1,700 meters. Flowering from June to September, this plant produces flowers with delicate, dense external hairs at the corolla sinuses. Growing as a slender plant 6 to 20 centimeters tall with a distinctively enlarged base, it emerges with fine glandular hairs on thin stalks. Its small stems feature short, generally three-celled glandular hairs that contribute to its subtle, intricate structure. As a root parasite, Howell's broomrape lacks typical leaves and instead attaches to host plant roots, drawing nutrients through specialized connections.
Identification and appearance
Key characters: Geographically isolated; slender stem enlarged at base, volcanic/serpentine soils, 6-20 cm
Habitat and range
Habitat: Volcanic and serpentine slopes, open chaparral, on
Elevation: 200-1700 m
Bloom period
Aphyllon validum subsp. howellii blooms Jun-Sep.
Conservation status
CNPS 4.3
How to tell it apart
vs Orobanche: Aphyllon and Orobanche are now considered the same genus; check current taxonomy.; vs Oenothera: Aphyllon is parasitic without green leaves; Oenothera has normal green leaves and grows independently.; vs Kopsiopsis: Aphyllon is hairy with separated bracts; Kopsiopsis is hairless with tightly overlapping bracts.; vs Pholisma: Aphyllon has upright purple flower spikes; Pholisma has round white flower heads at ground level.; vs Diplacus: Aphyllon is parasitic without green leaves; Diplacus has normal green leaves and colorful snapdragon flowers.
Frequently asked questions
Is Aphyllon validum subsp. howellii native to California?
Yes. Aphyllon validum subsp. howellii is native to California (recorded as native).
When does Aphyllon validum subsp. howellii bloom?
Aphyllon validum subsp. howellii blooms Jun-Sep.
What plant family does Aphyllon validum subsp. howellii belong to?
Aphyllon validum subsp. howellii is in the Orobanchaceae family, genus Aphyllon.
Is Aphyllon validum subsp. howellii rare or endangered?
Aphyllon validum subsp. howellii carries California Rare Plant Rank 4.3, state rank S3.
What habitat does Aphyllon validum subsp. howellii grow in?
Aphyllon validum subsp. howellii grows in Volcanic and serpentine slopes, open chaparral, on.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CalPhotos · CDFW CNDDB
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.