Rhamnaceae

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Buckthorn family
Tree986.JPG
Rhamnus cathartica L.
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Rosales[1]
Family: Rhamnaceae
Juss.
Type genus
Rhamnus
L.
Genera

See text.

Rhamnaceae Distribution.svg
The range of Rhamnaceae.
Synonyms

Frangulaceae DC.
Phylicaceae J.Agardh
Ziziphaceae Adans. ex Post & Kuntze[2]

Rhamnaceae is a large family of flowering plants, mostly trees, shrubs, and some vines, commonly called the Buckthorn Family.[3]

The family contains 50-60 genera and approximately 870-900 species. Rhamnaceae have a worldwide distribution, but are more common in the subtropical and tropical regions. The earliest fossil evidence of Rhamnaceae is from the Eocene.

Leaves of Rhamnaceae family members are simple, i.e., the leaf blades are not divided into smaller leaflets.[3] Leaves can be either alternate and spiraling, or opposite. Stipules are present. These leaves are modified into spines in many genera, in some (e.g. Paliurus spina-christi and Colletia cruciata) spectacularly so. Colletia stands out by having two axillary buds instead of one, one developing into a thorn, the other one into a shoot.

Flowers of Ceanothus cuneatus
Bisexual flower of a Helinus species, with 5 sepals and 5 petals, and a yellow, annular nectary disk. The small, clawed petals embrace the stamens.

The flowers are radially symmetrical. There are 5 (sometimes 4) separate sepals and 5 (sometimes 4 or none) separate petals. The petals may be white, yellowish, greenish, pink or blue, and are small and inconspicuous in most genera, though in some (e.g. Ceanothus) the dense clusters of flowers are conspicuous. The 5 or 4 stamens are opposite the petals.[3] The ovary is superior, with 2 or 3 ovules (or one by abortion).

The fruits are mostly berries, fleshy drupes or nuts. Some are adapted to wind carriage, but most are dispersed by mammals and birds. Chinese jujube is the fruit of the jujube tree (Ziziphus zizyphus) and is a major fruit in China.

The American genus Ceanothus, which has several showy ornamental species, has nitrogen-fixing root nodules.

Economic uses of Rhamnaceae are chiefly as ornamental plants and as the source of many brilliant green and yellow dyes. The wood of Rhamnus was also the most favoured species to make charcoal for use in gunpowder before the development of modern propellants.

Genera[edit]

Tribe Ampelozizipheae
Tribe Bathiorhamneae
Tribe Colletieae
Tribe Doerpfeldieae
Tribe Gouanieae
Tribe Maesopsideae
Tribe Paliurieae
Tribe Phyliceae
Tribe Pomaderreae
Tribe Rhamneae
Tribe Ventilagineae
Incertae sedis

References[edit]

  1. ^ Walter S. Judd and Richard G. Olmstead (2004). "A survey of tricolpate (eudicot) phylogenetic relationships". American Journal of Botany 91 (10): 1627–1644. doi:10.3732/ajb.91.10.1627. PMID 21652313.  (full text )
  2. ^ "Family: Rhamnaceae Juss., nom. cons.". Germplasm Resources Information Network. United States Department of Agriculture. 2003-01-17. Retrieved 2011-01-29. 
  3. ^ a b c Flowering Plants of the Santa Monica Mountains, Nancy Dale, 2nd Ed. 2000, p. 166
  4. ^ "Granitites". FloraBase. Department of Environment and Conservation, Government of Western Australia. 
  5. ^ "GRIN Genera of Rhamnaceae". Germplasm Resources Information Network. United. Retrieved 2011-01-29. 

External links[edit]