Lobelia aquaemontis E.Wimm.
Common names: Waterberg lobelia
Flowering with masses of sky-blue flowers, this delicate little lobelia gives a lovely display for many months in summer.
Lobelias are easily identified by their flowers with the two-lipped corolla and the tube split on the upper side. The upper lip consists of two often smaller and erect lobes and the lower lip of three spreading lobes. Most lobelias are blue but there are some species with mauve, white or pink flowers.
Lobelia aquaemontis is a small perennial, and it forms soft, bushy mounds, about 150 mm high and wide. The thin stems and divided leaves give the plants a delicate, lacy feel. Overall, the plants are pale green but close up one notices that the undersides of the leaves and many of the stems have a deep red tinge. It grows fast during the warm summer months and flowers continuously from spring, through summer to autumn. The single, pale blue flowers are proudly displayed at the tips of the thin stems.
Lobelia aquaemontis is not regarded as threatened.
Distribution and habitat
Lobelia aquaemontis occurs naturally in the northern part South Africa, known as the Limpopo Province.
Quite rare, it grows on the upper mountain slopes in the shade of sandstone rocks where the plants root in crevices and ledges. On the cool south-facing cliffs of the Waterberg, Ernst van Jaarsveld (pers. comm.) noted the following plants growing with Lobelia aquaemontis, Aeollanthus parviflorus, Agapanthus coddii, Aloe arborescens, Bulbine natalensis, Crassula cymbiformis, C. sarcocaulis, C. setulosa, and C. swaziensis. In the summer rainfall region, the average rainfall for the Waterberg is between 700-800 mm per year. Summer temperatures are moderate, with an average daily maximum of about 27°C and an average daily minimum for the region of about 12°C. The winters are cooler and frost is absent or light.
Derivation of name and historical aspects
The genus Lobelia was described in 1753 by Linnaeus who named it in honour of a Flemish nobleman, Matthias de L'Obel (1538-1616), a botanist and physician to King James 1. The species name aquaemontis is the combination of the Latin words, aquae, meaning waters/mineral springs, and montis, meaning mountain, a reference to the Waterberg.
Lobelia is a cosmopolitan genus of more than 360 species that are mostly found in the warmer tropical and subtropical regions of the world. The 69 indigenous species occur throughout most of South Africa as annuals, perennial herbs and small shrubs.
Lobelias are pollinated by a variety of bees and butterflies.
Lobelias are popular garden plants because of their blue flowers. The most popular species is Lobelia erinus which is used in planters, hanging baskets and edging plants in many countries. This dainty little lobelia produces a mass of blue flowers for many months of the year. Many of the other lobelias such as Lobelia comosa, L. coronopifolia and L. valida have much bigger and bluer flowers but they are not as vigorous and popular as garden plants. Lobelia aquaemontis shows promise as a new colourful perennial for display in pots.
Growing Lobelia aquaemontis
It thrives in full sun to semi-shade with regular watering, especially during the warm summer months when it is actively growing and flowering. At Kirstenbosch we have only grown this lobelia in pots and it has done particularly well in the large display planters in the Visitors Centre courtyard. Young flowering plants are planted in the display pots in November and within a month they cascade over the edges of the pot. The plants are removed in March to make place for the display of winter-growing spring bulbs. In summer the plants are fed once a month with an organic fertilizer.
The easiest way to propagate this lobelia is by division and removing the stems that root on the surface as they spread.
- Cupido, C.N. & Conrad, F. 2001. Lobelias in South Africa. Veld & Flora 87: 118, 119.
- Leistner, O.A. (ed.). 2000. Seeds plants of southern Africa : families and genera. Strelitzia 10. National Botanical Institute, Pretoria.
- Pooley, E. 1998. A field guide to wild flowers of KwaZulu-Natal and the Eastern Region. Natal Flora Publications Trust, Durban.
- Retief, E. & Herman, P.P.J. 1997. Plants of the northern provinces of South Africa. Strelitzia 6. National Botanical Institute, Pretoria.
- Smith , C.A. 1966. Common names of South African plants. Memoirs of the Botanical Survey of South Africa No. 35.
Liesl van der Walt
Plant Type: Ground Cover, Perennial
SA Distribution: Limpopo
Soil type: Sandy
Flowering season: Spring, Early Summer, Late Summer, Autumn
Flower colour: Blue, White
Aspect: Full Sun, Morning Sun (Semi Shade), Afternoon Sun (Semi Shade)
Gardening skill: Average