Willow hakea is a shrub or small tree adapted to a Mediterranean climate. It is capable of surviving hot, dry summers but not restricted to these conditions. It flowers in spring and early summer (September to January) in South Africa. Infestations of this plant replace indigenous vegetation and prevent the regeneration of indigenous species.
The wintergreen barberry is a dense evergreen shrub that can grow up to about 4 m tall. It has very characteristic three-branched thorns occurring at the nodes. The leaves are clustered, shiny dark green above, leathery and have a heavily spine margin. They develop a red colour in the winter months. The flowers are small, yellow and occur in clusters throughout the plant. The fruits are bluish-black berries that are toxic if ingested.
Ornamental, densely leafy evergreen shrub or small tree up to 4m high. Leaves are bright green above, paler below, with sharply toothed margins. Bright yellow, showy, trumpet-shaped flowers in terminal sprays from October to May. Brown, shiny fruit capsules 12-20cm long that split open to release papery winged seeds.
Pyracantha angustifolia (Rosaceae)
Evergreen shrub 2-4m high with stiff, spiny branches. Young shoots are covered in thick, yellowish down and woody spines which bear leaves. Dull, dark-green leaves above and grey-downy beneath. White flowers from October to December. Orange-red or orange-yellow berries. Fruits are poisonous.
Yellow Flag Iris
Yellow flag iris forms dense growth along riverbanks and the fringes of ponds, competing with indigenous species and altering water flow. It is a perennial moisture-loving plant with yellow flowers and long, strap-like leaves. It reaches a height of 100-150cm.
Yellow ginger lily
Vigorous plant up to 2m high. Broad, bright green leaves which sheath the stems. Fragrant flowers in spikes up to 30cm long from January to April. Each flower has a slender tube with three narrow and three broad, petal-like lobes. Flowers are yellow, sometimes reddish-yellow at the base.
Densely leafy, evergreen shrub or small tree up to 6m high with milky sap. Leaves are narrow, lance-shaped, bright green, glossy above and paler below. Flowers are yellow-orange, sometimes fragrant, trumpet-shaped, twisted in the bud. Fruits are drupe-like, slightly fleshy, green turning yellow, and finally hard turning black, broad triangular in outline with a raised ridge across the middle. Poisonous.
Yellow water lily
An aquatic plant with bright yellow flowers. Leaf blades and flowers appear above the water level. Leaves with wavy margins spread on the water surface. The yellow flowers open during the day and close at night. It grows in marshes and readily invades canals and other shallow waterways, sometimes becoming a nuisance.
Yellow water snowflake
A pond plant that produces star-shaped, yellow flowers throughout the season. The reddish brown and green lily-like leaves are decorative and make a pleasing background for the five-petalled, fringed yellow blossoms on the water's surface. Best grown in full sun to partial shade. Flowers in May to September.
Yellow-flowered Mexican poppy
Argemone Mexicana (Papaveraceae)
Very spiny annual herb growing up to 90cm high with stems that exude a yellow sap when cut. Grey or bluish-green spiny leaves with prominent white veins. Bright yellow flowers appear from September to January. Spiny, egg-shaped green fruit capsules turn brown and release numerous small black seeds. Poisonous, sap and spines cause skin irritation.