Rhamnaceae
plants, mostly trees, shrubs and some vines.
The family contains 55 genera and approximately 900 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 Eocene.
The simple leaves are alternate and spiraling, or they may be opposite. Stipules are present. These leaves are modified into spines in certain genera, as Paliurus and Coletia, some (e.g. Paliurus spina-christi and Colletia cruciata) spectacularly so. Coletia stands out by having two axillary buds instead of one, one developing into a thorn , the other one into a shoot.
The inconspicuous flowers are small and radially symmetrical. There are 5 (seldom 4) seperate sepals and 5 (sometimes 4 or none) separate petals. The 5 or 4 stamens are isomerous with the petals (i.e. one stamen opposite each petal). 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 (Zizyphus jujube) 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.
Genera
- Adolphia
- Alphitonia
- Alvimiantha
- Ampelozizyphus
- Auerodendron
- Bathiorhamnus
- Berchemia
- Berchemiella
- Blackallia
- Ceanothus
- Chaydaia
- Colletia
- Colubrina
- Condalia
- Crumenaria
- Cryptandra
- Discaria
- Doerpfeldia
- Emmenosperma
- Gouania
- Helinus
- Hovenia
- Karwinskia
- Kentrothamnus
- Krugiodendron
- Lasiodiscus
- Maesopsis
- Nesiota
- Noltea
- Phylica
- Pomaderris
- Reissekia
- Retanilla
- Reynosia
- Rhamnella
- Sageretia
- Schistocarpaea
- Scutia
- Siegfriedia
- Smythea
- Spyridium
- Talguenea
- Trevoa
- Trymalium
- Ventilago
- Ziziphus : Jujube
