General Info

Attractive Tree is up to 7m high. Leaves are imparipinnate. The pea-like, fragrant Flowers in racemes have pink and white petals. The Fruit is a cylindrical pod with 8-10 Seeds.

Description

Indigofera jucunda, Indigofera frutescens, Indigofera cylindrica.

RSA Tree No. 226.4.

Common names: Mountain Indigo, Tree indigo, River indigo.

Family: Fabaceae or Leguminosae (Pea, bean or legume family). After the Orchidaceae and the Asteraceae, the Fabaceae is the third largest Angiosperm (flowering plants) family with 700+ genera and close to 20 000 species. Local Tree genera include Acacia (Vauchellia, Senegalia), Albizia, Bauhinia, Bolusanthus, Burkea, Calpurnia, Colophospermum, Cyclopia, Dichrostachys, Erythrina, Erythrophleum, Faidherbia, Indigofera, Philenoptera and Schotia. The Fabaceae are recognisable by their fruit and by their pinnately compound Leaves. Leaves may also be simple and usually have stipules – some of which may be spinescent. Leaflets are usually entire. Flowers are bisexual and bracteate. Regular flowers usually have 4-5 sepals and the same number of petals. Irregular flowers have 4-5 sepals and 5 or less petals. Stamens have anthers that have 2 pollen sacs and there are usually at least twice the number of stamens as petals – often 10. The superior Ovary has one locule that may contain 1 or more ovules. The Stigma and Style are simple. The single carpel develops into the Fruit, which is usually a pod. The pod dehisces on both sides and may break into segments. Seeds vary.

Name derivation: Indigofera to bear (some species contain the dye indigo – similar to the colour of “blue jeans”). jucunda – pleasant – referring to the flowers. The genus Indigofera has over 800 species worldwide. The 210 species in the RSA are mainly herbs.

Conservation Status: L C. (Least Concern).

Tree

The Tree is small, up to 7m high. It can also be a stout shrub. The Stem is greyish brown and up to 13cm in diameter. The bark has distinct vertical markings (photo 49).

Leaves

The soft, delicate and alternately arranged Leaves are up to 10cm long. The plant is semi deciduous. The leaves are imparipinnate (pinnately compound leaf ending in a single leaflet). The 4-7 pairs of Leaflets, and a terminal one, are widely spaced and opposite or nearly so. They are up to 2,5cm long, hairless above and sparsely hairy below. Leaflets are elliptic or oblong or ovate (egg shaped). The Apex is round to notched and may be mucronate (having an abruptly projecting point). The Base narrows. The Petiole (leaf stalk) is up to 2cm long. Short Petiolules (stalks of leaflets) are present. Stipules (basal appendage of the petiole) are small.

Flowers

The fragrant, sweet pea like and very attractive Flowers small pink and white. They are arranged in short racemes (simple elongated inflorescences with stalked flowers) in the axils of leaves. Flowers are zygomorphic (irregular flower: when corolla is divisible into 2 equal halves in one plane only). The Calyx has 5 Sepals. The 5 Petals are bicoloured: coral-pink (or white or purple) and sweetly scented usually about 10mm long. The Vexillum (the standard or banner petal; the broad upper petal) is covered with fine, whitish hairs. There are 2 Wing petals and 2 joined, hairy Keel petals at the base. Apart from the one free Stamen immediately below the vexillum, the remaining 9 uniform stamens are joined about 2 thirds the way up the filaments. Anthers are terminal, uniform and apiculate (ending in a short, sharp, flexible point). The Pistil (the female element of the flower, composed of the Ovary, Style and Stigma) has a superior Ovary (said of an ovary that is free from the calyx or perianth) and the Style is bent upwards and ends in a capitate (formed like a head) Stigma. The plant has a long flowering time (Nov-Apr). The sweet Nectar attracts bees, which are probably responsible for pollination.

Fruit

The straight, smooth or hairy, cylindrical, and usually dehiscent Fruit is a Pod (a dry and usually dehiscent fruit) which is up to 50 x 4mm. Young pods are initially sheathed by a staminal tube (a floral tube usually formed by the fusion of the filaments). Each mature reddish-brown pod usually has 8 to 10 Seeds each with a hard bony testa (seed coat). A small oval hilum (a scar on the seed coat left by the stalk by which the ovule attaches to the ovary) is also visible. (May-Jul).

Distribution & Ecology

These plants can be Found in the Eastern Cape (East London, Pondoland), KwaZulu-Natal, Gauteng and Swaziland. They are often located in forest margins and riverbanks. Larvae of the Peablue Butterfly (Lampides boeticus) feed on the Leaves as well as the Flowers. This plant produces a great deal of Nectar. Many other insects are attracted to this plant and these insects attract birds. Insects responsible for pollination include the Garden Acraea butterfly (Acraea horta).

Ethnobotany

This is a good container plant. It grows easily from seed and cuttings and is best planted in a sunny place. It produces flowers after 2-3 years.

References

Boon, R. 2010. Pooley’s Trees of eastern South Africa. Flora and Fauna Publications Trust, Durban.

Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town.

Lawrence, G. H. M, 1951. Taxonomy of Vascular Plants, The Macmillan Company, New York. Tenth Printing 1965.

van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa, Struik, Cape Town.

Palmer, E. & Pitman, N. 1972. Trees of southern Africa, Balkema, Amsterdam, Cape Town.

 

http://redlist.sanbi.org/species.php?species=357-844

http://www.plantzafrica.com/planthij/indigofjuc.htm

http://www.operationwildflower.org.za/index.php/albums/genera-g-l/indigofera/indigofera-frutescens-thabo-1-1473