Rhamnaceae

Rhamnaceae
Temporal range: Late Cretaceous–Recent
Rhamnus pumila Turra
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Rosales
Family: Rhamnaceae
Juss.
Type genus
Rhamnus
Genera

See text

The range of Rhamnaceae.
Synonyms

Frangulaceae DC.
Phylicaceae J.Agardh
Ziziphaceae Adans. ex Post & Kuntze[1]

The Rhamnaceae are a large family of flowering plants, mostly trees, shrubs, and some vines, commonly called the buckthorn family.[2] Rhamnaceae is included in the order Rosales.[3]

The family contains about 55 genera and 950 species.[4] The Rhamnaceae have a worldwide distribution, but are more common in the subtropical and tropical regions. The earliest fossil evidence of Rhamnaceae is from the Late Cretaceous. Fossil flowers have been collected from the Upper Cretaceous of Mexico and the Paleocene of Argentina.[5]

Leaves of family Rhamnaceae members are simple, i.e., the leaf blades are not divided into smaller leaflets.[2] Leaves can be either alternate or opposite. Stipules are present. These leaves are modified into spines in many genera, in some (e.g. Paliurus spina-christi and Colletia paradoxa) 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 Helinus, with five sepals and petals, and a yellow, annular nectary disk. The small, clawed petals embrace the stamens.
Flowers of Ziziphus mucronata
Flowers of Rhamnus saxatilis

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.[2] The ovary is mostly 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 jujuba) and is a major fruit in China.

The American genus Ceanothus, which has several showy ornamental species, has nitrogen-fixing root nodules.[6]

Economic uses of the 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.

  1. ^ "Family: Rhamnaceae Juss., nom. cons". Germplasm Resources Information Network. United States Department of Agriculture. 2003-01-17. Archived from the original on 2011-06-05. Retrieved 2011-01-29.
  2. ^ a b c Flowering Plants of the Santa Monica Mountains, Nancy Dale, 2nd Ed. 2000, p. 166
  3. ^ 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.
  4. ^ Christenhusz MJ, Byng JW (2016). "The number of known plants species in the world and its annual increase". Phytotaxa. 261 (3): 201–217. doi:10.11646/phytotaxa.261.3.1.
  5. ^ Jud NA, Gandolfo MA, Iglesias A, Wilf P (2017-05-10). "Flowering after disaster: Early Danian buckthorn (Rhamnaceae) flowers and leaves from Patagonia". PLOS ONE. 12 (5): e0176164. Bibcode:2017PLoSO..1276164J. doi:10.1371/journal.pone.0176164. ISSN 1932-6203. PMC 5425202. PMID 28489895.
  6. ^ Kummerow J, Alexander JV, Neel JW, Fishbeck K (January 1978). "Symbiotic Nitrogen Fixation in Ceanothus Roots". American Journal of Botany. 65 (1): 63–69. doi:10.1002/j.1537-2197.1978.tb10836.x. JSTOR 2442555.