The African tulip tree is an evergreen species indigenous to western Africa. It has been introduced throughout the tropics and is threatening biodiversity in many parts of the Pacific islands. It favours moist habitats and will grow best in sheltered tropical areas. The tree invades both abandoned agricultural land and closed forest. This species loves rich soil, but puts up with just about any type of soil.
A coniferous tree growing up to 15m high, conical in shape with a short trunk when young and rounded to oblong with a crooked trunk when older. Crown open with silvery-grey bark becoming darker. Grey-green to yellow-green leaf needles in bundles of two 4-8cm long. It invades grasslands and fynbos, particularly on dry soils
The Algerian ash is a medium-sized, deciduous tree growing to 20–30m tall with a trunk up to 1.5m in diameter. It is not commonly planted anymore, however large numbers of adult trees can still be seen growing in suburban areas. The flowers are produced in inflorescences, which can be male, hermaphrodite or mixed male and hermaphrodite. Flowering occurs in early spring.
This tree grows 8-10m high with a straight, smooth, grey trunk with pyramidal crown. Leaves are bright green and smooth, or brownish-velvety beneath along the midrib and veins. Small male and female flowers on separate trees from April to May in large clusters, along densely greyish-yellow, light brown hairy axes. Female flowers red. Shiny brown fruits. Poisonous leaves.
Deciduous tree 10 to 20 m high with a spreading crown and often more than one trunk; bark is greenish smooth at first, aging to brown and rough. Leaves bright green, paler and sometimes densely hairy beneath, turning yellow in autumn; 3 – 9 pinnate, but mostly with 5 leaflets; leaflets coarsely toothed, 50 – 100 mm long.
This fast-growing species is particularly invasive along waterways (i.e. in riparian areas) and in sheltered forests in temperate zones, but it has the potential to invade other habitats.