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Rhamnus crocea

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 crocea Nutt.
Habit: Shrub, < 2 m. Stem: bark gray; branches many, spreading, stiff, rooting; twigs +- thorn-tipped, red or red-purple. Leaf: evergreen; petiole 1--4 mm; blade 10--15 mm, elliptic to obovate, thick, glabrous, abaxially flat, base acute to rounded, tip rounded, margin sharp-toothed or entire, veins not prominent. Inflorescence: 1--6-flowered, glabrous; pedicel 1--6 mm. Flower: generally unisexual; hypanthium +- 2 mm wide; sepals 4; petals 0. Fruit: 2-stoned, 6 mm, red.
Ecology: Coastal-sage scrub, chaparral, woodland; Elevation: < 1150 m. Bioregional Distribution: KR, NCoRO, SNH, CW, SW; Distribution Outside California: Baja California. Flowering Time: Jan--Apr
Unabridged Note: Rhamnus crocea and its closely related species were considered conspecific by C.B. Wolf (1938) (e.g., Rhamnus crocea subsp. crocea, Rhamnus crocea subsp. ilicifolia, Rhamnus crocea subsp. pilosa, Rhamnus crocea subsp. pirifolia). Another, Rhamnus insula Kellogg (Rhamnus insula subsp. insula (Kellogg) C.B. Wolf) is restricted to Mexico (Baja California). The species are distinctive but intermediates exist. C.B. Wolf (1938) identified Rhamnus crocea/ilicifolia intermediates from Marin Co. to the California/Mexicoico boundary; Rhamnus ilicifolia/insula, Rhamnus crocea/pilosa, and Rhamnus ilicifolia/pilosa intermediates occur in southern California, especially in San Diego Co. Clearly, the Rhamnus crocea complex in California needs studies using modern techniques.
eFlora Treatment Author: John O. Sawyer, Jr.
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botanical illustration including Rhamnus crocea


Citation for this treatment: John O. Sawyer, Jr. 2016. Rhamnus crocea, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on October 27, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora,, accessed on October 27, 2016.

Rhamnus crocea
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© 2016 Keir Morse
Rhamnus crocea
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© 2016 Keir Morse
Rhamnus crocea
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© 2008 Neal Kramer
Rhamnus crocea
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© 2016 Keir Morse
Rhamnus crocea
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© 2016 Keir Morse
Rhamnus crocea
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© 2016 Keir Morse

More photos of Rhamnus crocea in CalPhotos

Geographic subdivisions for Rhamnus crocea:
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.