Jepson eFlora: Taxon page
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Rhamnus alnifolia

Higher Taxonomy
Family: RhamnaceaeView DescriptionDichotomous Key

Habit: [Perennial herb] shrub, tree, generally erect, often thorny. Leaf: simple, generally alternate, often clustered on short-shoots; stipules generally present, occasionally modified into spines; generally petioled; blade pinnate-veined or 1--5-ribbed from base. Inflorescence: cyme, panicle, umbel, or flowers 1 or clustered in axils or on short-shoots. Flower: generally bisexual, radial; hypanthium subtending, surrounding, or partly fused to ovary; sepals 4--5; petals 0, 4--5, generally clawed; stamens 0, 4--5, alternate sepals, attached to hypanthium top, each generally fitting into a petal concavity; disk (0 or) between stamens, ovary, thin to fleshy, entire or lobed, free from ovary, adherent or fused to hypanthium; ovary superior or +- inferior, chambers [1]2--4, 1--2-ovuled, style 1, stigma entire or 2--3-lobed. Fruit: capsule, drupe.
Genera In Family: 50--52 genera, 950 species: especially tropics, subtropics some cultivated (Ceanothus; Frangula; Rhamnus; Ziziphus).
eFlora Treatment Author: John O. Sawyer, Jr., except as noted
Scientific Editor: Steve Boyd, Thomas J. Rosatti.
Genus: RhamnusView DescriptionDichotomous Key

Common Name: BUCKTHORN
Habit: Shrub, small tree, < 10 m. Stem: branches alternate, stiff or flexible; twigs generally not thorn-tipped; winter bud scales present, generally +- 3 mm. Leaf: scattered along branches or clustered on short-shoots, deciduous or evergreen; stipules generally deciduous; petioles generally glabrous; blade veins prominent or not. Inflorescence: flowers 1 or in cyme-like clusters in axils. Flower: unisexual (bisexual), generally on separate pls, generally < 3 mm; hypanthium bell-shaped to cup-like, 2--3 mm wide; sepals 4--5, thin, spreading, not keeled adaxially; petals 0 or 4--5; disk thin, adhering to hypanthium; ovary appearing superior or partly inferior, chambers 2--4, each 1-ovuled, style 1, stigma 2--4-lobed. Fruit: drupe, 2--3[4]-stoned.
Species In Genus: 110 species: temperate, few tropics; some of value in medicine or as dyes. Etymology: (Greek: name for plants of this genus) Note: W.H. Brewer collected Rhamnus cathartica L., considered invasive in parts of United States, in 1861, but it apparently never naturalized. Other taxa in TJM (1993) moved to Frangula.

Rhamnus alnifolia L'Hér.
Habit: Shrub, < 2 m. Stem: bark gray; branches puberulent to glabrous; twigs brown; winter bud scales +- 5 mm. Leaf: deciduous; petiole 4--15 mm; blade 45--110 mm, elliptic to ovate, thin enough to transmit light, glabrous to puberulent, base acute to obtuse, tip acute, margin irregularly toothed, veins prominent, arched. Inflorescence: 1--3-flowered; pedicels 2--10 mm. Flower: unisexual; hypanthium +- 1 mm wide; sepals 5; petals 0, 4, 5. Fruit: 3-stoned, +- 8 mm, black.
Ecology: Wet meadow edges, seeps, stream sides; Elevation: 1450--2020 m. Bioregional Distribution: n SNH; Distribution Outside California: to Canada, northern Rocky Mountains, northern United States. Flowering Time: May--Jul
Synonyms: Apetlorhamnus alnifolia (L'Hér.) Nieuwl.
eFlora Treatment Author: John O. Sawyer, Jr.
Jepson Online Interchange
Listed on CNPS Rare Plant Inventory

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Citation for this treatment: John O. Sawyer, Jr. 2016. Rhamnus alnifolia, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on May 24, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora,, accessed on May 24, 2016.

Rhamnus alnifolia
click for enlargement
© 2015 Steve Matson
Rhamnus alnifolia
click for enlargement
© 2015 Steve Matson
Rhamnus alnifolia
click for enlargement
© 2015 Steve Matson
Rhamnus alnifolia
click for enlargement
© 2015 Steve Matson
Rhamnus alnifolia
click for enlargement
© 2015 Steve Matson
Rhamnus alnifolia
click for enlargement
© 2015 Steve Matson

More photos of Rhamnus alnifolia in CalPhotos

Geographic subdivisions for Rhamnus alnifolia:
n SNH;
Markers link to CCH specimen records. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

View elevation by latitude chart
Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.