Family: Boraginaceae

Class: Angiospermae: Dicotyledones
Common names:
forget-me-not, borage family

Trichodesma  in the Boraginaceae

Members of the family Boraginaceae are herbs, shrubs or trees, characterized by leaves with rough hairs, inflorescences sometimes coiled at their tips, and fruit a capsule or drupe (fleshy) of four 1-seeded nutlets.

Description
Boraginaceae is a family displaying a range of differences in habit, leaf, inflorescence, flower and fruit morphology.

The species are mainly herbs (see Anchusa capensis), but shrubs or trees, usually multi-stemmed, also occur (see Ehretia rigida and Cordia caffra ). Their life cycles may be annual, multiseasonal or perennial. The stems of the herbaceous species are erect, procumbent (lying on the ground without rooting at the nodes) or decumbent (spreading horizontally at first but then growing upwards).

The plants are variously hairy. Setae (stiff hairs) with 1- or 2- or 3-layered, multicellular bases, unbranched or branched hairs and unbranched multicellular glandular hairs occur. The leaves are simple, with or without a leaf stalk. The inflorescences are often coiled at the apex, uncoiling as the flowers open. The corolla is sympetalous (having petals which are partly fused); the throat may be naked, hairy, with pouch-like swellings (gibbosities) or has fornices (small scales) present. The colour of the corolla varies from white, yellow, shades of blue and purple to brownish red or pink. The stamens are exserted or included, borne on the corolla. Pollen grains of different types are produced in the anthers. The fruit is a capsule or drupe of four 1-seeded nutlets, the nutlets are glabrous or variously ornamented.

Distribution
The family Boraginaceae comprises about 135 genera and 2 600 species, distributed throughout the tropical, subtropical, and temperate regions of the world. A broad family concept is followed here, regarding the families Hydrophyllaceae and Lennoaceae as synonyms of Boraginaceae. Members occur on all the continents and also on many islands such as the Cape Verde Islands and Madagascar. Although Boraginaceae is only a medium-sized family (21 genera and 110 species) in the Flora of southern Africa (FSA) compared to the largest family Asteraceae (246 genera and 2 240 species), the members are widespread over the area.The members of Boraginaceae occur in the Desert, Forest, Fynbos, Grassland, Nama-Karoo, Savanna, Succulent Karoo and Thicket Biomes of the FSA region. They are therefore found in a variety of habitats, often inhabiting disturbed places like road verges and are thus easily collected and recorded.

Distribution map

Different types of plant distribution patterns are found among members of the family Boraginaceae in southern Africa. Cordia, the largest genus in the family with an estimated 350 species is pantropical with about eight species occurring in southern Africa. Besides Lobostemon and Echiostachys, which is more or less endemic in the Western Cape (winter rainfall), all other genera occur either elsewhere in Africa or in the world. The genera Anchusa, Cynoglossum, Lappula, Lithospermum and Myosotis have indigenous members described from southern Africa with their nearest relatives in Europe and Asia.

Name and History
In 1789 Antoine Laurent de Jussieu published a plant classification system, Genera plantarum, with a description of 'Borragineae' as one of 100 orders (i.e. families). Many of his families are still maintained in modern classifications. De Jussieu based 'Borragineae' on the genus Borago L. When Linnaeus established the genus Borago, he used the Latin name burra, meaning a hairy garment, in allusion to its hairy leaves.

Trichodesma augustifolium

Ecology
Members of Boraginaceae in southern Africa occur mainly in summer rainfall regions where grassland and savanna prevail. They are subject not only to winter drought and frost, but also to natural and man-made veld fires. These species are adapted to survive unfavourable conditions by means of sturdy, often very old, fire-resistant rootstocks and mass seed production after fire-stimulated flowering, for example Trichodesma angustifolium. The plants resprout and flower shortly after burning, usually well before the onset of the rainy season. Observations of the effect of fire on Trichodesma physaloides (chocolate bells)[see above] in the Pretoria National Botanical Garden, National Botanical Institute, South Africa, showed that unburned plants of the species did not flower at all or produced only a few inflorescences, as opposed to burned plants of the species in the same grassland that sprouted and produced inflorescences in profusion after a natural fire. It seems that a change in temperature also induces flowering of plants-Ehretia rigida subsp. nervifolia, a multistemmed shrub, flowers abundantly for a very short time even before the rains start.

An important feature in the southern African flora is the presence of members of genera that are naturalized aliens. Two species of Echium were introduced into southern Africa, possibly as part of stock feed or birdseed. They have become troublesome invaders and are now declared weeds.

Heliotropium amplexicaule

An often neglected aspect of species is their adaptations for dispersal. The fruits and seeds of members of the family Boraginaceae in the southern African flora are dispersed in various ways. The bright orange-red drupes of Ehretia and Cordia are dispersed by birds or mammals such as monkeys, members of these genera are often found in bush clumps and along fences. Ants carrying the nutlets of Heliotropium amplexicaule into their nests were observed in the Pretoria National Botanical Garden where this species is a most successful invader of sandy, disturbed areas. Seeds of the genera Codon and Wellstedia are dispersed by the opening actions of their capsules, whereas nutlets of the genera Cynoglossum, Lappula, Rochelia and some members of Trichodesma and Afrotysonia are characterized by the presence of barbed hooks (glochidia) that are attachment devices that enable seeds to hook on to passersby to "catch a ride".


Economic and cultural value

LobostemonFruits of the southern African Boraginaceae species are edible, but not very tasty. Some species are browsed by game. A tea is made from the dried leaves, stalks and berries of Ehretia rigida subsp. nervifolia. Dried, ground root powder mixed with cold water is used for diarrhoea (Trichodesma angustifolia subsp. angustifolia). Leaves of Lobostemon, (with pretty bell-shaped flowers) fried in sweet oil and leaf decoctions are old Cape remedies for ringworm, sores, ulcers, burns and wounds (Joffe 2001).

In the Garden
Plants are easily propagated from seed or cuttings. The horticultural potential of many southern African species of this family is still to be explored.


Reference and further reading

  • Joffe, P. 2001. Creative gardening with indigenous plants: a South African guide. Briza Publications, Pretoria.


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