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Rhamnus
BUCKTHORN

Higher Taxonomy
Family: RhamnaceaeView DescriptionDichotomous Key

Common Name: BUCKTHORN FAMILY
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.

Rhamnus
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.
eFlora Treatment Author: John O. Sawyer, Jr.
Jepson Online Interchange
Key to Rhamnus

Previous taxon: Frangula rubra subsp. yosemitana
Next taxon: Rhamnus alaternus

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Citation for this treatment: John O. Sawyer, Jr. 2016. Rhamnus, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=8844, accessed on July 23, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on July 23, 2016.


Rhamnus crocea
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© 2007 Neal Kramer
Rhamnus cathartica
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© 2016 Keir Morse
Rhamnus cathartica
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© 2016 Keir Morse
Rhamnus ilicifolia
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© 2014 Keir Morse
Rhamnus ilicifolia
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© 2014 Keir Morse
Rhamnus pirifolia
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© 2014 Steve Matson

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