Bloomipedia
Lewis' mock orange (Philadelphus lewisii)
Photo: Daughter Dad via iNaturalist · CC BY 4.0 · resized

Flower profile

Lewis' mock orange

Philadelphus lewisii

Lewis' mock orange (Philadelphus lewisii) is a shrub in the Hydrangeaceae family, native in the lower 48 states, blooming mostly May–July across the U.S.

★ Official state flower of Idaho (1931)Native in the lower 48

Lewis' mock orange is a flowering plant that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 2 states, and across the U.S. it's most often seen in bloom in May–July.

5states where USDA records it
2Bloomipedia state lists include it
4,445U.S. sightings*

*iNaturalist research-grade observations, as of October 17, 2026.

On our lists for: Idaho, Montana

🏅
Idaho's official state flower since 1931. Visit the Idaho page → Idaho Code § 67-4502

Quick look

Philadelphus lewisii, the Lewis' mock-orange, mock-orange, Gordon's mockorange, wild mockorange, Indian arrowwood, or syringa, is a deciduous shrub native to western North America, and is the state flower of Idaho.

  • It belongs to the Hydrangeaceae family. iNaturalist
  • USDA PLANTS describes it as a shrub with a perennial life cycle. USDA PLANTS
  • USDA PLANTS lists it as native in the lower 48 states and records it in 5 states. USDA PLANTS
  • NatureServe lists it as native to Montana and Idaho. NatureServe
  • USDA PLANTS lists its flower color as white. USDA PLANTS
  • USDA PLANTS gives its bloom period as late spring. USDA PLANTS
  • USDA PLANTS lists a mature height of about 12 ft. USDA PLANTS
  • iNaturalist has 522 research-grade sightings of it in Montana, ranking #87 among the 128 flowers on our Montana list. iNaturalist
  • iNaturalist has 496 research-grade sightings of it in Idaho, ranking #69 among the 143 flowers on our Idaho list. iNaturalist

When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (370 records)
Bloom time in the 2 states whose Bloomipedia list includes it
StateTypePeak bloomSightings*
MontanaNativefew records (31)522
IdahoNativefew records (11)496

Conservation status

Federal (U.S. ESA)
Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. USFWS ECOS
NatureServe global
G5 Secure worldwide. NatureServe
Montana
No list Montana has no state law listing endangered or threatened plants, so we show NatureServe's Montana ranks instead. NatureServe: S5, secure in Montana.
Idaho
No list Idaho has no state law listing endangered or threatened plants, so we show NatureServe's Idaho ranks instead. NatureServe: SNR, not yet ranked in Idaho.
Rare elsewhere
No other U.S. state ranks it S1, S2, SH or SX.

Checked October 17, 2026. Rankings and lists can change, so follow the links for the latest.

Can you eat it?

For peopleNot well documented

None of the sources we checked (NC State Extension (no page for this plant), USDA PLANTS) say whether it's edible or poisonous for people.

For petsNot well documented

It isn't on the ASPCA plant list.

🌿 Never eat a wild plant unless you're certain of its ID; this isn't medical advice. Worried about a person? Call Poison Control at 1-800-222-1222. Worried about a pet? Call your vet.

Where does it grow?

USDA PLANTS records lewis' mock orange in 5 states.

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

California, Idaho, Montana, Oregon, Washington.

Idaho counties with USDA records: Ada, Adams, Blaine, Boise, Bonner, Boundary, Butte, Clearwater, Custer, Elmore, Gem, Gooding, Idaho, Kootenai, Latah, Lemhi, Lewis, Nez Perce, Owyhee, Shoshone, Valley, Washington.

Growing conditions

USDA PLANTS gives Lewis' mock orange a high shade tolerance, medium drought tolerance and low moisture use. It is rated for soil pH 7.0 to 8.0 and winter lows down to 7 °F.

Shade tolerance
High
Drought tolerance
Medium
Moisture use
Low
Soil textures it is adapted to
coarse, medium
Soil pH range
7.0 to 8.0
Minimum temperature tolerated
7 °F
Frost-free days needed (minimum)
140
Annual precipitation range
19 to 69 inches
Minimum root depth
6 inches
Salinity tolerance
None
Fertility requirement
Low
Growth rate
Moderate
Lifespan
Moderate
Active growth period
Spring and Summer
Fruit or seed
Brown · Summer to Fall
Can be propagated by
bare root, container, cuttings, seed
Commercial availability
Contracting Only

From the USDA PLANTS characteristics data for PHLE4. USDA ratings are general guidance for the species, not a guarantee for your garden.

Names, range and relatives

Native status by region (USDA PLANTS): Canada: Native; Lower 48 states: Native.

Other scientific names (synonyms in USDA PLANTS): Philadelphus gordonianus.

County records: USDA PLANTS lists it in 114 counties across 4 states; the most are in Washington (36), Oregon (34), California (22).

Other Philadelphus on Bloomipedia (1): Sweet mock orange.

More from the Hydrangeaceae family (9 on Bloomipedia; most observed first): Wild hydrangea, Oakleaf hydrangea, Cliff fendlerbush, Kanawao, Bigleaf hydrangea, Panicle hydrangea, Mountain hydrangea, Slender deutzia.

More Montana flowers

Sweet mock orange (Philadelphus coronarius)

Sweet mock orange

Philadelphus coronarius

🌷 Flowering shrub

🌷 Grown in Montana gardens
Panicle hydrangea (Hydrangea paniculata)

Panicle hydrangea

Hydrangea paniculata

🌷 Flowering shrub

🌷 Grown in Montana gardens
Fireweed (Chamaenerion angustifolium)

Fireweed

Chamaenerion angustifolium

Native

🌼 Blooms in MT: July–August

Sources