Learn all about the different types of Thunbergia flowers and discover how these pretty small flowers with their signature black ‘eye’ in the middle can be grown even when you don't have enough space for a garden.
Thunbergia flowers are one of the prettiest small flowers you will come across. The plant is a creeper, which means it doesn’t really require a lot of dedicated space to grow. It can easily climb up walls, spill out of hanging flower baskets and pots, and grow in raised flower beds, or even as a houseplant. Besides being so good-looking, with their signature black ‘eye’ in the middle surrounded by vibrant petals, Thunbergia flowers are also one of the easiest to plant, according to gardeners and botanists.
These three properties make Thunbergias one of the most preferred plants to grow in backyards and gardens. With only a little effort, your house and your garden can be dotted with these adorable, colorful flowers. They need regular maintenance, though; not to keep them growing but to keep them in control, as they are aggressive growers.
Table of Contents
Etymology and History
Thunbergia is an old Latin name. These pretty flowers are named after a Swedish botanist of the early 19th century, Carl Peter Thunberg. Because of his massive contributions to the world of botany, many species of plants have been named after him. Thunbergia flowers are just one example of a plant species which was named in reverence of the great botanist and naturalist. He brought back Thunbergias from his travels to Africa and Asia.
Some species of the plants are more commonly known as black-eyed Susan vines.
Most species of Thunbergias are native to the tropical regions of Africa and southern Asia. Belonging to the family Acanthaceae, Thunbergia is a genus of flowering plants. They are vigorous plants, which grow aggressively and bloom from summer to fall.
Thunbergias are a climbing plant and grow in a creeping fashion, twining up wall spaces, garden centers, railings, and fences. Their colorful flowers are abundant among the foliage.
They are fast growers, too, and quickly escape their initial growing spaces, invading surrounding spaces. If left unchecked, the Thunbergia plant might end up covering your entire wall in a thick covering of leaves and tiny flowers in a mere few months. Thunbergia’s growth rate is well-know; some species of the plant are considered weeds in some countries. Regular trimming of the plant helps keep the plant looking maintained and neat.
The leaves of the plant are middle-green to dark green. They are course, shiny, and heart-shaped. Among the thick foliage, colorful tubular flowers grow. These flowers are the main defining feature of the plant. The small, five-petaled flowers are often instantly recognizable because of their ‘eye.’ Some species of Thunbergias have a distinctive black round spot in the middle, with the solid colored petals surrounding it, while most exist as hanging or creeping clock vines.
The flowers come in dozens of colors, such as yellow, orange, violet, and red, all surrounding the inky dark center. The different colored flowers are sprouted by different species of Thunbergias. Growing a couple of the species together will give your garden a splattering of different colors. The flowers, though they do not emit a distinctive scent, do attract bees and other insects, encouraging pollination.
Thunbergia flowers are easy on the eye and easy to plant, making this plant a popular one to be grown inside and around homes. It can be the plant you keep on your kitchen’s windowsill or hanging in a garden basket on your door. It needs to be stemmed and cut regularly to maintain its appearance. The plant can be grown from its stems, too, so the trimmed stems can be used to grow the plant elsewhere.
Thunbergias bloom voraciously from summer through fall. No deadheading is necessary; the flowers grow on their own. If left unattended, the plant will climb onto anything and everything in its way, so it needs to be maintained.
Nurseries and markets don’t normally have to grow, potted Thunbergias in their gardens. That is because the plant is best grown from seeds. Plant a few seeds when there is no threat of frost left for the year. You can initially plant the seed indoors in a pot till the seed is ready to germinate, or you can plant it directly in an open space, press lightly and lightly cover it with rich, loamy soil. Make sure to soak the soil in water for a day before planting.
The plant grows easily in temperatures all year round, except when it’s frosty. The seed will start to grow within 7-10 days approximately, and it requires lots of sunshine. Planting it in places where it can bathe in the full sun all day is preferred, though a little afternoon shade could also be beneficial. Make sure to keep the soil moist; Thunbergia doesn’t like sitting in drenched soil, but they also can’t bear dry, hot soil, so make sure to strike a balance.
Once the seedling has emerged, the plant will grow and flower quickly. Make sure to provide them with a lattice or a circular rod nearby that they can climb while growing. Since they grow so vigorously, they tend to eat up the nutrients in the soil pretty fast. Add rich compost or fertilizer occasionally, or whenever you feel it’s necessary.
Types of Thunbergia Flowers
There are several species of the plant. They differ mostly in the color of their flowers, though some do have distinct leaves and a few other properties too. Listed below are 18 species of the 31 Thunbergia plants that the Plant List accepts.
- Thunbergia alata
- Thunbergia annua
- Thunbergia atriplicifolia
- Thunbergia battiscombei
- Thunbergia coccinea
- Thunbergia cordata
- Thunbergia elegans
- Thunbergia erecta
- Thunbergia fragrans
- Thunbergia gibsonii
- Thunbergia grandiflora
- Thunbergia gregorii
- Thunbergia ikbaliana
- Thunbergia laurifolia
- Thunbergia lutea
- Thunbergia mysorensis
- Thunbergia vogeliana
- Thunbergia wightiana
We’ll be exploring and diving into details of some of the most common species of Thunbergias that are available.
Perhaps the most common, and recognized species of the Thunbergia family is the Thunbergia alata. When someone says Thunbergia flowers, this is the one that most picture. Popularly called Black-Eyed Susan, because of its characteristic dark funnel in the center of the flower, it is the most sought-after and planted species in most households.
Native to South Africa, this perennial climber is a favorite among many because of its non-demanding growing requirements. It enjoys warm, humid weather but is hardy to colder climates, too. Grown mostly because of its visual appeal, the black-eyed Susan is the perfect choice for covering your fence or an ugly wall.
The species gained its name from the Latin word ‘alatus,’ which means winged. This, most likely, refers to the winged petioles of the Thunbergia alata, which is one of the most distinctive visual identities of the plant, besides its black eye. ‘Alata’ could, however, also refer to the seeds of the black-eyed Susan, which have a natural protective covering that gives off the appearance of wings.
While Thunbergia alata needs its fill of sunlight, it prefers some time away from the sun as well. In Africa, it usually grows on the edges of forests. The flowers themselves are a bright orange-yellow color, with the signature black-eye in the middle. The corolla is shaped like a trumpet’s horn, while the leaves are either heart-shaped or arrow-shaped, lightly haired and sometimes toothed.
Aboriginal to Africa, Thunbergia erecta is also known as bush clock vine, because it can be trained as either a bush or a vine. It is also known as “King’s Mantle,” perhaps because of the rich, royal shade of purple that the flower exhibits. Thunbergia erecta possibly earned the epithet of erecta (which means upright) because it is a straight standing plant. Though native to Africa, it is cultivated widely in the Indian subcontinent.
The flowers themselves are a sight to behold. Trumpet-shaped, like many of its relatives, the flower’s tube flares out to reveal 5 petals of deep purple and violet, with a pale yellow or creamy color at the base of the throat. The stem has long, ovate leaves, growing in opposing directions and the flowers are located between the axils in a pair or singly. The plant can reach up to 2 m in both height and width.
There is also a subspecies of Thunbergia erecta, which grows white flowers and smaller leaves, known as Alba. The King’s Mantle can be grown in pots as well as trained to grow over a trellis. It all depends on how you want the plant to grow.
Another Thunbergia species of Indian and Southeast Asian origin, the Thunbergia fragrans can grow pretty well in tropical areas of other parts of the world, too, like Hawaii, Florida, and the likes. The Thunbergia fragrans is also known as white lady, angel wings, or sweet clock vine. It is also known as fragrant Thunbergia, answering the question of the etymology of this specific species. However, some say that the flower of white lady is scentless, and it’s the plant that emits a certain fragrance, to which it owes its name.
Thunbergia fragrans is a perennial vine, with green, oblong leaves and white flowers, similar in shape to Thunbergia gregorii. The flowers are about 2 cm wide and have a subtle, cream-colored center instead of the black-eyed one of the Thunbergia alata. The petiole also includes beaked seed capsules.
It is a fast grower, which has earned it the title of an invasive weed. Though it prefers to grow in wild forests, wastelands, roadsides, and similar locations, it has now been naturalized and used as a decorative plant.
Another common species of Thunbergia is the Thunbergia Grandiflora. It has quite a few names that it is known by; blue skyflower, skyflower, Bengali clock vine, Bengali trumpet, blue trumpet vine, and sky vine. As the alternative names hint, this species births Thunbergia flowers whose soft-blue colors almost resemble that of the sky.
It is native to Southeast Asia, China, Nepal, and Burma, though it is naturalized almost all around the globe now. The Bengali clock vine grows in a hanging vine, with elliptic leaves growing in opposing directions, varying significantly in size.
Grandiflora literally means ‘large-flowered’ referring to the bigger flower size as compared to the flowers of its relatives. They bloom in subtropical environments year-round. Trumpet-shaped, with colors ranging from lavender-blue to bluish-white, the skyflower has a pale yellow or cream interior. The flowers have a flaring head and a width of 7.5 cm.
The plant has rope-like stems and long pointed leaves that can grow up to 5 cm in length. They are also often toothed. Though typically a wildflower, it is grown as a showy plant now.
The alternate names, laurel clock vine or blue trumpet vine, give away a clear picture of the appearance of this pretty flower. Native to the Indomalayan region, this clock vine is a pale lavender shade that makes for a gorgeous combination with its medium-green leaves.
Similar in appearance to the Bengal Clockvine, laurifolia is an evergreen vine, generally only differing in the size of the flowers. The flowers of the Thunbergia laurifolia are comparatively smaller than those of the Grandiflora, at about 5-7 cm in width. It earned the epithet of laurifolia because of its slightly serrated laurel-shaped leaves.
In Thailand, the leaves of the laurifolia are considered to have detoxifying effects and are popularly used in traditional medicine as an antidote to poison and drugs. While in Australia, this species has been declared as an invasive weed because of its vigorous growth and prolific blooming. In urban settings, it can be trained over a lattice for thick foliage and blossoms.
Thunbergia mysorensis is indigenous to southern India. Predictably enough, it is also known as the Mysore trumpet vine or Indian clock vine. The name Mysorensis refers to the exact place in India, Mysore, where it grows in abundance and from where it was discovered. It has now become naturalized everywhere because of its use in decorative planting.
The Indian clock vine is often referred to as ‘doll’s shoes’ and ‘lady’s slippers’ in the local tongue, because of the shape and size of its flowers. These bi-colored flowers have bright flower tips and yellow throats. They hang on long, trailing vines in tropical mountain areas, where they grow vigorously all year round because of the favorable conditions. They resemble the Grandiflora species more than the alata.
With long, green leaves, and large, bold flowers, these vines can grow up to 6 meters, and make for beautiful additions to garden and porches, hanging over other plants in the garden and providing shade. It is a sun-loving plant that requires plenty of water, as is typical of the tropical, monsoon climate of the Indian mountains. It is also attractive to sunbirds, hummingbirds, and bees, encouraging pollination.
Thunbergia gregorii is one of the better-known species of the Thunbergia plant. Known more commonly as the orange clock vine, it is a common sight in urban neighborhoods and gardens, especially in cities close to the sea – like California. It has no known uses or benefits and is simply planted as an ornamental plant. As the name suggests, it is a bright orange, a vibrant flower which blooms all year round. However, it is distinguishable from its relative, Thunbergia alata, easily by the absence of the dark center. It is native to tropical Africa and is tolerant of coastal conditions.
English botanist Spencer Moore named this flower after his friend and colleague, John Walter Gregory, a Scottish explorer, who had discovered the plant species and brought back samples from one of his travels to the Great Rift Valley in Africa. Another name of the species is Thunbergia gibsonii, though it remains unresolved on the Plant List.
While the orange clock vine is a creeper like most of its relatives, it only grows to a height of about 2-3 meters and often grows as a groundcover, too. If given the room to climb, it can quickly climb over a trellis and flower all year round in warmer climates. Stem-cuttings can be used for propagation.
Thunbergia flowers are beautiful, vibrant, colorful, and look great in just about any area where they’re planted. They not only look great on their own but the different varieties, when planted together, add a splash of color to any garden or backyard. People who want to plant this species just need to be careful about its growth habit. It is, after all, a fast grower, and will take over any space if it is given a chance to do so.
Home Stratosphere is an award-winning home and garden online publication that’s a result of our talented researchers and writers who work directly with hundreds of professional interior designers, furniture designers, landscape designers and architects from around the world to create helpful, informative, entertaining and inspiring articles and design galleries.