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Pacific Waterleaf (Hydrophyllum tenuipes)
Global: G4G5 Provincial: S2S3 COSEWIC: n/a BC List: Blue
Documented South Coast Occurrence
Distribution: Pacific waterleaf is native to southwestern British Columbia west of
the Cascades, south to northern California. In British Columbia this species is
extremely rare, found only in the lower Fraser Valley and southeastern Vancouver
Island. There are only four confirmed populations in the Fraser Valley, with three
populations on Sumas Mountain and one in the Cultus Lake/Vedder Mountain area.
Population sizes range from small clonal patches of approximately nine square feet
to an extensive colony. Since no comprehensive inventory has been conducted for
this species in BC, it may occur in other locations in the Fraser Valley.
Description: Blooming in early spring, Pacific waterleaf is a deciduous perennial
with solitary flowering stems that are 20-80 cm tall. Plants spread vegetatively by
above-ground rhizomes to form clonal colonies, but this species also spreads by
seed. The leaves are the most distinctive feature. They are mostly basal and hairy
with long stalks. The leaf blade is divided into 5 (rarely up to 9) toothed leaflets,
with all but the lowermost pair joined together. Flowering occurs from May to July
when plants display compact clusters of tiny funnel-shaped flowers (5-7 mm long)
that range in colour from greenish-white to blue or purple. The stamens are very
noticeable and extend past the petals. After flowering, tiny round capsules develop,
each containing one to three seeds that are dispersed in the fall.
Look’s Like?
Pacific waterleaf resembles Fendlers’ waterleaf (Hydrophyllum fendleri var.
albifrons), which overlaps in range but is much more common. Comparing the
leaves is the easiest way to tell these two apart. Fendlers’ waterleaf has 7 to 15
leaflets in opposite pairs, while Pacific waterleaf typically has 5 leaflets with all but
the lowermost pair joined together.
Habitat: Pacific waterleaf is a shade-loving species that requires high spring light
levels with deep summer shade. It is found in riparian zones of rivers and creeks
and on seepage slopes and floodplains, within deciduous and mixed woodlands. In
BC it is often found beneath bigleaf maple canopies. South of the border, this
species is commonly associated with Oregon ash (Fraxinus latifolia). Pacific
waterleaf prefers soil with a well-developed, deep, organic layer. It occurs at low to
middle elevations below 1500 m.
Critical Features
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Pacific waterleaf is particularly susceptible to catastrophic loss. Almost half
of the known populations occur on Sumas Mountain where they are threatened
by intensive subdivision development.
Because this species is restricted to riparian habitats, it is especially vulnerable
to activities that alter site hydrology.
Seasonal Life Cycle
Jan Feb Mar Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Flowering
Capsule production and seed
dispersal
Threats
 In the lower Fraser Valley subdivision development and logging operations are
the main threats to Pacific waterleaf.
 Harvesting of plants and seeds also poses a threat. This species is used for
native plant gardening and in landscaping for erosion control.
Conservation Objectives
 Conduct a regional survey of Pacific waterleaf and prepare a species status
report in order to assess population numbers and threat levels.
 This species’ is presently blue-listed but the few populations combined with
the vulnerability of this species to catastrophic loss indicates that the species
status should be upgraded to red-listed. This species should be assessed by
COSEWIC and added to the species covered by the federal Species At Risk
Act.
Management Practices Check List
 Promote habitat connectivity by retaining old growth and mature forest stands
where possible.
 Retain a deciduous component where it occurs naturally in mixed forest sites.
 Protect local hydrological conditions, particularly where subdivision
development is ongoing.
 Maintain site microclimate and moisture conditions within core areas by
implementing a management zone large enough to buffer populations.
 Minimize the introduction of invasive species by minimizing disturbance and
edge effects.
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Protect populations from herbicide spray drift from adjacent logging
operations. Do not use fertilizers, herbicides or pesticides near populations.
Avoid trampling and soil compaction as this species is very sensitive to soil
conditions.
Within sites maintain the canopy and percent cover for populations in order to
retain necessary light levels in spring and shade in summer. Do not remove
canopy trees that provide critical shade. Avoid selective logging which
changes the forest composition.
Avoid tree harvesting and salvaging in the vicinity of populations.
Minimize the construction of roads, trails or stream crossings, especially uphill
from populations.
Minimize recreational activities, especially intensive activities such as
mountain biking, near known populations. Minimize development of
recreational trails or facilities.
Restrict harvesting of the plant, including seeds or capsules by collectors.
Main References/Literature Cited
British Columbia Conservation Data Centre. 2008. BC Species and Ecosystems Explorer
[http://a100.gov.bc.ca/pub/eswp/]. B.C. Ministry of Environment, Victoria, B.C.
Accessed June, 2008.
Douglas, G.W., D.V. Meidinger, and J. Pojar (editors). 1999. Illustrated Flora of British
Columbia. Volume 3: Dicotyledons (Diapensiaceae Through Onagraceae). British
Columbia Ministry of Environment, Lands & Parks and B.C. Ministry of Forests.
Victoria. 423 p.
Halse, Richard. 2007. Hydrophyllum tenuipes treatment. Jepson Interchange, Jepson Flora
Project. Copyright Regents of the University of California. Web publication.
Available: http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?4518,4546,4550.
Accessed March 2007.
Jarvis, Cassy. (Editor) 2008. Burke Museum of Natural History and Culture
[www.washington.edu/burkemuseum/]. University of Washington, Seattle, Washington.
Accessed June 2008.
Klinkenberg, Brian. (Editor) 2006. E-Flora BC: Electronic Atlas of the Plants of British
Columbia [www.eflora.bc.ca]. Lab for Advanced Spatial Analysis, Department of
Geography, University of British Columbia, Vancouver.
NatureServe. 2008. NatureServe Explorer: An online encyclopedia of life
[http://www.natureserve.org/explorer/]. Version 7.0. NatureServe, Arlington, Virginia.
Accessed June, 2008 .
Pojar, Jim and Andy MacKinnon. (Editors) 1994. Plants of Coastal British Columbia,
Including Washington, Oregon & Alaska. B.C. Forest Service, Research Program. Lone
Pine Publishing, Vancouver.
SARA Public Registry Office. 2007. Species at Risk Public Registry
[http://www.sararegistry.gc.ca]. Environment Canada, Government of Canada, Ottawa,
Ontario. Accessed June, 2008.
Image credits: All photographs by Ryan Durand.