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John O. Sawyer, Jr., except as noted

[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.
50–52 genera, 950 species: especially tropics, subtropics some cultivated (Ceanothus; Frangula; Rhamnus; Ziziphus). [Richardson et al. 2000 Amer J Bot 87:1309–1324] —Scientific Editors: Steve Boyd, Thomas J. Rosatti.
Unabridged references: [Brizicky 1965 J Arnold Arbor 45:439–463; Richardson et al. 2000 Kew Bull 55:311–341]

Key to Rhamnaceae

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 plants, 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.
110 species: temperate, few tropics; some of value in medicine or as dyes. (Greek: name for plants of this genus) [Bolmgren & Oxelman 2004 Taxon 53:383–390] 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.
Unabridged references: [Wolf 1938 Rancho Santa Ana Bot Gard Monogr 1]

Key to Rhamnus

R. pirifolia Greene ISLAND REDBERRY
Small tree, < 10 m. Stem: bark gray; branches ascending; twigs purple. Leaf: evergreen; petiole 5–10 mm; blade 20–50 mm, elliptic, thick, glabrous, abaxially concave, base rounded, tip acute to rounded, mucronate, margin entire to toothed, veins prominent. Inflorescence: 1–6-flowered, glabrous; pedicels 3–6 mm. Flower: generally unisexual; hypanthium ± 2 mm wide; sepals 4; petals 0. Fruit: 2-stoned, 6–8 mm, red.
Coastal-sage scrub, chaparral; 10–520 m. Channel Islands; Mexico (Guadalupe Island). [Rhamnus catalinae Davidson; Rhamnus crocea Nutt. var. insularis Sargent; Rhamnus crocea subsp. pirifolia (Greene) C.B. Wolf; Rhamnus crocea var. pirifolia (Greene) Little] Jan–Apr [Online Interchange] {CNPS list}

Previous taxon: Rhamnus pilosa
Next taxon: Ziziphus


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Citation for the whole project: Jepson Flora Project (eds.) 2013. Jepson eFlora,, accessed on Nov 29 2015
Citation for this treatment: [Author of taxon treatment] 2013. Rhamnus, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on Nov 29 2015

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Geographic subdivisions indicated for the distribution of Rhamnus pirifolia Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
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).

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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.