Howellia aquatilis
Water howellia
Family: Campanulaceae · Type: Herb · Native
Conservation status: CNPS 2B.2 · Delisted
Howellia aquatilis (Water howellia) is a native California herb in the Campanulaceae family, recognized by Monotypic genus with disjunct populations from Pacific Northwest to northern California; federally threatened.
Water howellia is a rare (CNPS 2B.2) California native annual found in northern coastal ranges of California in seasonal ponds at elevations of 1,100 to 1,500 meters. Flowering from June to August, this aquatic plant produces delicate white flowers in solitary axillary arrangements with a distinctive split corolla tube. Growing with submersed or floating stems 10 to 60 centimeters long, it has an ascending to erect growth habit characteristic of aquatic environments. Its alternate leaves are linear, entire or minutely toothed, sessile along the stem and well-adapted to underwater conditions. The fruit is an ellipsoid structure 5 to 13 millimeters long that opens irregularly on its sides, containing 2 to 4 shiny, chestnut-brown seeds.
Identification and appearance
Key characters: Monotypic genus with disjunct populations from Pacific Northwest to northern California; federally threatened
Habitat and range
Habitat: Seasonal ponds
Elevation: 1100-1500 m
California counties: Mendocino
Outside California: to Washington, Montana
Bloom period
Howellia aquatilis blooms Jun-Aug.
Conservation status
CNPS 2B.2 · Delisted
How to tell it apart
vs Nemacladus: Howellia has 5 separate petals on short stalks; Nemacladus has threadlike tubular flowers on long stalks.; vs Legenere: Howellia has alternate linear leaves; Legenere has whorled leaves in rosettes.; vs Porterella: Howellia has plain white flowers with separate petals; Porterella has blue flowers with yellow ridges.; vs Lobelia: Howellia is aquatic annual with ellipsoid pods; Lobelia is perennial with spherical pods.; vs Downingia: Howellia flowers have short visible stalks 1-8mm; Downingia flowers sit directly on stem with no stalk.
Frequently asked questions
Is Howellia aquatilis native to California?
Yes. Howellia aquatilis is native to California (recorded as native).
When does Howellia aquatilis bloom?
Howellia aquatilis blooms Jun-Aug.
Where in California does Howellia aquatilis grow?
Howellia aquatilis occurs in Mendocino, at elevations of 1100-1500 m.
What plant family does Howellia aquatilis belong to?
Howellia aquatilis is in the Campanulaceae family, genus Howellia.
Is Howellia aquatilis rare or endangered?
Howellia aquatilis carries California Rare Plant Rank 2B.2, state rank S2.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · 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.