Hibbertia, also known as Guinea flower and climbing Guinea plant, is a genus of about 115 different species of perennial shrubs and trailing or climbing plants in the Dilleniaceae family. The vast majority of these plants are native to Australia, but some species are found in the Pacific Islands and Madagascar. These generally disease- and pest-resistant plants are a favorite of gardeners in warm climates. Plants in this genus produce flowers in only two colors: yellow and orange. One species in this genus is in jeopardy of becoming extinct.
A total of 111 species of Hibbertia are various shades of yellow. The remaining four species are various shades of orange. All species produce five-petaled flowers from early spring to late summer, depending on location. During flowering, the evergreen foliage is almost completely covered by the plant's abundant flowers. Plants typically grow from 18 to 36 inches (45-90 cm) tall and can be up to 138 inches (350 cm) across.
Hibbertia thrives in U.S. Department of Agriculture hardiness zones nine to 12. It prefers full overhead sun and partial shade in the afternoon. Plants in this genus are quite hardy and can tolerate high winds, mildly saline soil, salt winds and light frost. In addition, they can live in a variety of different soil conditions with pH levels ranging from mildly acidic to mildly alkaline. The plants are often found along coastal sand dunes, in woodlands, and in Eucalyptus forests. All species require soil that has good drainage and it should not be allowed to dry out between waterings. The soil should remain moist, but not muddy.
The plants can be propagated by taking stem cuttings during the winter. Sowing seeds does not generally yield good results. Plants grown from seed are reportedly shorter lived than those propagated by stem cuttings.
Most Hibbertia species are fairly resistant to disease. Plants living near the coast do tend to be susceptible to mites. These mites create silver scars on the leaves. Spraying with an insecticidal soap designed to be used on plants in this genus will take care of any mite problems.
Some gardeners use low-growing Hibbertia species as a perennial ground cover. The plants are also used to add a burst of yellow or orange color to flower gardens or shrub beds. Trailing species are often used in hanging baskets or on trellises.
One species of is in danger of extinction. Only two areas in Australia have populations of Hibbertia species nova sp. nov. 'Menai.' One population of this species is found near southern Sydney and the other grows along the southern coast of New South Wales. Hibbertia sp. nov. 'Menai' growing in New South Wales is on the endangered list. The overall national conservation status of this species in Australia is listed as critically endangered.
The government of Australia is taking a three-pronged approach to save the plants. Urban development is being limited in areas where it has been responsible for much of the species' loss. Weeds, which threaten to overtake the endangered plants, are being kept under control. The government is also trying to keep the remaining plant populations from being trampled by humans and animals. With so much of this species already destroyed, recovering enough of the plants to remove it from the critically endangered list may be a difficult, laborious task.