E-Flora BC: Electronic Atlas of the Flora of British Columbia

Philadelphus lewisii Pursh
mock-orange (Lewis' mock orange)
Hydrangeaceae (Hydrangea family)

Introduction to Vascular Plants

© Bob Thacker  Email the photographer   (Photo ID #81114)

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Distribution of Philadelphus lewisii
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Species Information

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Deciduous shrub, erect, loosely branched, 1.5-3 m tall; bark reddish-brown, turning grey and flaking off in patches; twigs glabrous to hairy.
Opposite, short-stalked, widely egg-shaped to rounded, 3-5 cm long, margins entire to toothed, flat with 3 major veins from the leaf base, slightly sand-papery to touch.
Inflorescence of 3-15 flowers in a raceme; petals 4, white, 5-20 mm long, oblong; calyces top-shaped or bell-shaped, 4-6 mm long, 4-lobed, the lobes egg-shaped, 5-6 mm long; stamens yellow, numerous, unequal.
Capsules, 4-chambered, woody, 1 cm long; seeds many, spindle-shaped, brown, 2.5-3 mm long.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
Blooming Period:
Late Spring
Fruit/Seed characteristics:
Colour: Brown
Present from Summer to Fall
Source:  The USDA

Habitat / Range

Moist to dry talus slopes, shrublands, streamsides and open forests in the lowland, steppe and montane zones; frequent in S BC; E to SW AB and S to MT, ID and N CA.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Philadelphus lewisii

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres) 1 640 1540
Slope Gradient (%) 0 39 170
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
1 196 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
0 2 7
Modal Nutrient Regime
Number of field plots
 species was recorded in:
Modal BEC Zone Class
All BEC Zones (# of stations/zone) species was recorded in: BG(18), CDF(29), ESSF(1), ICH(123), IDF(156), MS(4), PP(73)

Ecological Indicator Information

A shade-intolerant. submontane to subalpine, North American deciduous shrub distributed more in the Cordilleran than the Pacific region. Occurs in continental cool temperate and cool semiarid climates on moderately dry to fresh, nitrogen-medium soils; its occurrence increases with increasing temperature and continentality and decreases with increasing elevation. Scattered in open-canopy Douglas-fir forests; in the coast-interior ecotone more frequent on water-shedding sites than water-receiving sites. Characteristic of dry continental forests.

SourceIndicator Plants of Coastal British Columbia (Information applies to coastal locations only)


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is cool temperate & cool semiarid.

Synonyms and Alternate Names

Philadelphus gordonianus Lindl.
Philadelphus lewisii subsp. gordonianus (Lindl.) Munz
Philadelphus lewisii var. angustifolius (Rydb.) Hu
Philadelphus lewisii var. ellipticus Hu
Philadelphus lewisii var. gordonianus (Lindl.) Jeps.
Philadelphus lewisii var. helleri (Rydb.) Hu
Philadelphus lewisii var. intermedius (A. Nelson) Hu
Philadelphus lewisii var. oblongifolius Hu
Philadelphus lewisii var. parvifolius Hu
Philadelphus lewisii var. platyphyllus (Rydb.) Hu

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References