Rhamnaceae
Rhamnaceae Juss. comprises approximately 55–60 genera and 900–1,000 species, distributed worldwide, especially in tropical, subtropical, and temperate regions. Molecular phylogenetic studies support the monophyly of the family and have clarified relationships among its major genera, including Ziziphus, Rhamnus, Ceanothus, Berchemia, and Paliurus. Members are characterized by woody growth forms, simple leaves with characteristic arcuate venation, small greenish flowers, superior ovaries, and drupaceous or capsular fruits.
Key characteristics
- Trees, shrubs, or woody climbers
- Branches often thorny
- Leaves simple with arcuate venation
- Stipules small, sometimes modified into spines
- Flowers small, greenish, and actinomorphic
- Nectar disc conspicuous
- Ovary superior or partly inferior
- Fruit a drupe, capsule, or schizocarp
Distribution
Rhamnaceae has a nearly cosmopolitan distribution, with greatest diversity in Mediterranean regions, tropical America, Africa, Australia, and temperate Asia. Members occur in woodlands, dry forests, scrublands, deserts, riverbanks, coastal habitats, grasslands, and mountain slopes, ranging from sea level to alpine regions. In Pakistan, Rhamnaceae is widely distributed throughout, the Salt Range, Potohar Plateau, Thal Desert, Cholistan Desert, Sulaiman Range, and Himalayan foothills. Species are common in thorn forests, dry scrublands, riverine forests, rocky slopes, cultivated lands, and mountain valleys.