Grewia occidentalis, more commonly known as the lavender star flower tree, is a small tree that originates from southern regions of Africa. It thrives in habitats that include evergreen forests, wooded grasslands, coastal dunes, and the arid lands of the Great Karoo. In the United States, this tree is grown in the southern states of Arizona, California, Florida, and Texas.
Lavender star flower is important to the wildlife in its native habit. Both livestock and wild animals alike graze on the leaves of this tree, as do several species of butterfly. Birds and mammals consume fruits. In some regions, the fruit is dried and later boiled in milk to create a beverage or make flavored yogurt. Ripe fruit may also be brewed into beer.
The wood is used for spear shafts and to fashion bows. Bark may be pounded and used for shampoo, or boiled and used to treat woods. Lavender star flower is also grown in some parts of the world as an attractive bonsai tree.
Known by the botanical name of Grewia occidentalis, the lavender star flower tree is a member of the genus Grewia that was named in honor of English botanist, Nehemiah Grew. Grew is often referred to as the father of plant anatomy.
Grewia occidentalis is sometimes sold under the name Grewia caffra.
The two most common names for this tree are crossberry and lavender star flower. It is also called the four-corner and buttonwood.
Preferred USDA Hardiness Zones
Lavender star flower thrives in warmer climates. Its preferred USDA zones are 9a to 11.
Size and Shape
A compact evergreen, the lavender star flower can be grown as a small tree, shrub, container plant, and even a bonsai tree. When allowed to grow as a standard tree it will reach a maximum size of about 9 to 10 feet in height and spread. Contrast that with the pruned bonsai form of no more than 10 inches, and you’ll appreciate the versatility of this small tree.
Lavender star flower prefers full sun, which promotes the best growth and more robust blooming. However, it will tolerate shade as well. Ideal planting locations are those with western or southern exposure.
Foliage, Flowers, and Fruit
The simple evergreen leaves of the lavender star flower are deep green, shiny and a bit hairy in texture. When flowers appear, it is obvious where this species derives its name. Appearing in the summer, the star-shaped flowers are beautiful lavender in color with yellow, filamentous stamens in the center of the blossom.
Following the blossoms, four-lobed berries are formed, which gives the tree its other common names of crossberry or four corners. The fruit is reddish brown to orange in color and remains on the tree for an extended period of time.
Lavender star does not have an aggressive root system that will cause problems with sidewalls, making it suitable for planting near walkways and buildings. It is also popular for butterfly gardens, where the foliage and nectar attract both butterflies and birds alike.
Due to its smaller size, it is also well suited to use as a container for patios or in small yards. It can also be trained to grow as an espalier, grown indoors as a small tree, or pruned to become a bonsai tree.
For optimal growth, fertilize three times per year with an acid-based fertilizer. An annual iron supplement is also recommended.
Keep moist and do not allow the soil to completely dry out. Provide plenty of direct sunlight. Placing them in a southern exposure is preferred, or use grow lights if placed indoors at a location with less than four to six hours of bright sunlight per day.
Lavender stars can be propagated from cuttings in the spring or from seed. Seeds will germinate in two to three weeks at 70° F.
Maintenance and Pruning
This species can be pruned heavily, as needed at any time of year. To promote flowering, cut back immediately after blossoms have dropped. This will also maintain a good overall shape.
Repotting of container trees is best done in mid-summer. Water heavily after repotting, but provide drainage so it does not stand in water.
Pests and Diseases
This species is susceptible to very few diseases and pests. Butterfly larvae enjoy the foliage and may cause some leaf damage.