Rhamnaceae

Buckthorn family
Rhamnus pumila Turra
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Rosales
Family:	Rhamnaceae Juss.
Type genus
Rhamnus L.
Genera
See text.
The range of Rhamnaceae.
Synonyms
Frangulaceae DC. Phylicaceae J.Agardh Ziziphaceae Adans. ex Post & Kuntze

The Rhamnaceae are a large family of flowering plants, mostly trees, shrubs, and some vines, commonly called the buckthorn family.

The family contains about 55 genera and 950 species. 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.

Leaves of Rhamnaceae family members are simple, i.e., the leaf blades are not divided into smaller leaflets. 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 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. 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 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.

Genera

Tribe Ampelozizipheae Ampelozizyphus Ducke Tribe Bathiorhamneae Bathiorhamnus Capuron Tribe Colletieae Adolphia Meisn. Colletia Comm. ex Juss. Discaria Hook. Kentrothamnus Suess. & Overkott Ochetophila Poepp. ex Reissek Retanilla (DC.) Brongn. Trevoa Miers ex Hook. Tribe Doerpfeldieae Doerpfeldia Urb. Tribe Gouanieae Alvimiantha Grey-Wilson Crumenaria Mart. Gouania Jacq. Helinus E.Mey. ex Endl. Johnstonalia Tortosa (originally named Johnstonia; by some treated as Gouania) Pleuranthodes Weberb. Reissekia Endl. Tribe Maesopsideae Maesopsis Engl. Tribe Paliureae Hovenia Thunb. Paliurus Mill. Ziziphus Mill. Sarcomphalus P.Browne emend. Hauenschild Tribe Phyliceae Nesiota† Hook.f. Noltea Rchb. Phylica L. Trichocephalus Brogn. Tribe Pomaderreae Blackallia C.A.Gardner Cryptandra Sm. Papistylus Kellermann, Rye & K.R.Thiele Polianthon K.R.Thiele Pomaderris Labill. Serichonus K.R.Thiele Siegfriedia C.A.Gardner Spyridium Fenzl Stenanthemum Reissek Trymalium Fenzl

Tribe Rhamneae Auerodendron Urb. Berchemia Neck. ex DC. Berchemiella Nakai Condalia Cav. Frangula Mill. Karwinskia Zucc. Krugiodendron Urb. Reynosia Griseb. Rhamnella Miq. Rhamnidium Reissek Rhamnus L. Sageretia Brongn. Scutia (Comm. ex DC.) Brongn. Tribe Ventilagineae Smythea Seem. Ventilago Gaertn. Incertae sedis Alphitonia Endl. (close to Colubrina) Araracuara Fern.Alonso Ceanothus L. (close to Pomaderreae) Chaydaia Pit. (by some treated as Rhamnella) Colubrina Rich. ex Brongn. Emmenosperma F.Muell. (close to Colubrina) Granitites Rye (close to Alphitonia) Hybosperma Urb. (by some treated as Colubrina) Jaffrea H.C.Hopkins & Pillon Lasiodiscus Hook.f. Schistocarpaea F.Muell. (maybe belonging to Colletieae) Talguenea Miers ex Endl. (by some treated as Trevoa)

Systematics

Modern molecular phylogenetics recommend the following clade-based classification of Rhamnaceae:

Elaeagnaceae (outgroup) Rhamnaceae Ampeloziziphoids Ventilago Bathiorhamnus Ampelozizyphus Doerpfeldia Rhamnoids Maesopsis Scutia Rhamnus Frangula Sageretia Berchemia Rhamnidium Rhamnella Reynosia Krugiodendron Karwinskia Condalia Ziziphoids Schistocarpeia Hovenia Ziziphus Paliurus Gouania Helinus Pleuranthodes Crumenaria Reissekia Lasiodiscus Colubrina Emmenosperma Noltea Trichocephalus Nesiota Phylica Granitites Alphitonia Colletieae Adolphia Trevoa Talguenea Discaria Kentrothamnus Colletia Retanilla Ceanothus Pomaderreae Siegfriedia Cryptandra Stenanthemum Trymalium Pomaderris Spyridium

External links

• Rhamnaceae of Mongolia in FloraGREIF