Alder-leaved Buckthorn (RWMWD Plant Guide)

Alder-leaved Buckthorn

Rhamnus alnifolia

Summary ³

Rhamnus alnifolia is a species of flowering plant in the buckthorn family known by the common names alderleaf buckthorn, or alder buckthorn. It is native to North America, where it is known mainly from the southern half of Canada and the northern half of the United States and California. It can be found in forested habitat.

Description ⁴

Family:
Rhamnaceae (Buckthorn)

Height:
2 to 3 feet

Habit:
Shrub; Branches up to 1½” in diameter; Spreads by layering

Leaves:
Leaves (up to 4½” long and 2½” wide) are alternately attached and ovate in shape, with blunt-toothed edges, pointed tips, and 5-8 lateral veins per side that curve toward the leaf tip. Leaf stalks are typically red.

Bark:
Young bark is typically thin, smooth, and gray to gray-brown in color. Mature bark is thin, rough-textured, and grayish to reddish brown in color.

Flower:
Flowers (up to ¼” across) grow in clusters of 1-3 from leaf axils. Individual flowers are yellow-green in color, petalless, and star-shaped, characterized by 5 triangular sepals with pointed tips.

Fruit:
Fruit (up to ⅓” across) is berry-like, shiny, and nearly black in color, often with a lightly grooved surface. It is similar in appearance to the fruit of Common Buckthorn (Rhamnus cathartica), but is generally somewhat larger in size.

Bloom time:
May-June

Fall color:
Yellow-orange, often with some green

Nicknames:
Dwarf Alder, American Alder Buckthorn

Habitat:
Alder-leaved buckthorn prefers full to partial shade, and wet to well-drained, loamy soils. It tolerates most soil types, including calcareous soils. It is commonly found growing in bogs, fens, swamps, marshes, shorelines, and moist woodlands.

Wildlife Benefits:
Fruit is a food source for many species of birds. Flowers are attractive to bees and butterflies.

Notes:
This species is distinguishable from non-native, invasive species of buckthorn by its 5-petaled flowers and short stature. Both Common Buckthorn (Rhamnus cathartica) and Glossy Buckthorn (Frangula alnus) have 4-petaled flowers and typically grow taller than Alder-leaved Buckthorn.

Do not consume the fruit of this species - it is mildly poisonous and has a natural laxative effect on humans.

References:
https://www.minnesotawildflowers.info/shrub/alder-leaved-buckthorn
https://www.nrs.fs.fed.us/data/il/ilpin/local-resources/includes/2491.txt
https://www.wildflower.org/plants/result.php?id_plant=RHAL
http://fieldguide.mt.gov/speciesDetail.aspx?elcode=PDRHA0C010

Range ⁴

Sources and Credits

(c) mhays, some rights reserved (CC BY-NC), uploaded by mhays
Adapted by Ramsey-Washington Metro Watershed District from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Rhamnus_alnifolia
(c) Ramsey-Washington Metro Watershed District, some rights reserved (CC BY-SA)

More Info

iNat Map

Family	Rhamnaceae
Habit	Shrub
Life cycle	perennial
Origin	native
Bloom time	(5) May, (6) June
*sites	Snail Lake

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