Family : Lobeliaceae
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A large cosmopolitan genus of
many garden ornamentals of which the popular Lobelia
erinus, one of sixty-nine species, is native to South
Africa.
Description
Species in this genus are
blue, purple, white or pink flowering annuals, perennial herbs, and small
shrubs. The leaves are alternate, simple, and without stipules, often
containing a watery or milky sap.
The flowers are irregular and
bisexual, and are borne singly or in racemes, umbles or spikes. Petals, sepals
and stamens are in fives. The petals are fused forming a two-lipped corolla,
which consists of spreading lobes and a split tube.
The upper lip consists of two
often smaller and erect lobes and the lower lip of three spreading lobes. The
petals are inserted on a two-chambered inferior ovary and the stamens are
attached to the base of the corolla.
Filaments are fused at least
half of their length and anthers are fused into a tube around the style.
Anthers are often tipped with a tuft of short hair. The style is simple with as
many stigmatic lobes as carpels. The fruit is a dehiscent capsule.
Distribution
Lobelia, comprising
more than 360 species, has a cosmopolitan distribution, although especially
rich in the tropical and subtropical regions. Only sixty-nine species occur in
South Africa. The genus is found throughout the country and grows in a variety
of habitats from sheltered to exposed rocky slopes, sand dunes, sandy flats,
shady, damp, coastal mountain slopes and forest floors.
Ecology
Lobelia flowers
achieve cross-pollination by being protandrous (male reproductive organs mature
first). The style pushes through the tube that is formed by the fused anthers
and drives the pollen out at the top, where it is collected by insects.
After the style has emerged
completely, the stigmatic lobes separate and the female stage of the flower
begins. The stigma is now receptive to pollen from another plant. Pollinators
include a variety of bees and butterflies.
Economic and cultural value
The long flowering period,
ease of cultivation and stunning flowers have made many Lobelia species
popular in the horticultural industry.
A few species such as L. pinifolia, L.
erinus, L. coronopifolia and L. flaccida have been reportedly used as medicinal plants. For
example, the roots of L. pinifolia have been used in remedies for skin disease,
chronic rheumatism and gout. The alkaloid lobeline is most likely responsible
for the medicinal properties of Lobelia.
In the Garden
Lobelias make excellent edging plants in flowerbeds or can be grown in
containers and hanging baskets. L. erinus is the most widely cultivated species in the
genus.
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It has been cultivated since the seventeenth century and commonly used in flowerbeds. The rare, L. valida also makes an excellent bedding plant and is often planted in beds at Kirstenbosch garden. L. pteropoda from the Transkei area makes an attractive hanging basket specimen. Most species can easily be grown from seed.
Source: www.plantzafrica.com
