Notes on Terminalia sericea

Notes on Terminalia sericea Burch. ex DC. (Combretaceae)

Vernacular Names

Sand-geelhout, silver leaf terminalia

Conservation Status

Potential problem species as it may form dense thickets.

Introduction

Terminalia sericea is a small to medium sized tree of the Combretaceae (Cole 1982) that occurs in northern and eastern Namibia, and on the Waterberg plateau. The species forms an important part of the dry woodland savanna as classified by Giess (1971) acting as a pioneer. In the areas in which the species occurs in Namibia it often colonizes open areas such as cleared cutlines and fire breaks or areas opened by timber harvesting. The species has a tendency to form thickets, and may produce a very large biomass (Rutherford 1982, Shackleton 2001).

The leaves and roots have some medicinal properties, and are being used by the rural populations to cure various ailments. The timber itself may be used for as fire wood, for building, implement handles and furniture (van Rooyen 2001) and therefore represents an important resource for rural communities.

The following review consolidates information on T. sericea to provide a basis for management.

Distribution and Occurrence

Geographical distribution

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Habitat

Very frost hardy [rutherford1981]

Growth Requirements

On deep and loamy sand ([leger1997])

Description

Form

Shrub or tree 3-15m high, young twigs are reddish-brown ([bri1963]). Tree size seems to be linked to location or region. For example, the trees in the Mudumu National Park, eastern Caprivi, Namibia, attain larger dimensions than those further south and east such as, for instance in Namibia’s Omaheke or Otjozondjupa regions. This may be due to differences in rainfall.

Branches off at stem for most of its length, branches inclined 30-45o ([pendle1982])

Bark and Wood

  • Bark is grayish, peeling in narrow longitudinal strips ([bri1963]).

  • Bark on trunk greyish-brown to grey-black; blackish on twigs and peeling to show lighter underbark (Drummond 1981) .

  • Wood is yellow, hard, fine-grained ([bri1963]).

  • Young stems and branches often bear galls ([leger1997])

Leaves

  • Leaves appear a grayish–green in the raining season, due to white pubescence. This seems to decrease with age ([bri1963])

  • Leaves are characteristically borne at the tips of branchlets giving the tree its name.

  • Leaf flush before first rain ([childes1989])

Flowers

  • leaf flush before rain; peak flowering occurs with peak leaf flush; many flower more than once in a wet season.([childes1984])

  • The flowers are unpleasantly scented, the smell being reminiscent of old socks. Saar (2000)therefore suggests that flies carry out pollination.

Fruit

  • Fruit dispersal by wind ([childes1989])

  • Most fruit found under the canopy of the species.

  • Many fruit may be empty ([msanga1998])

Rooting

  • Surface roots ranged from 12-35cm in depth ([knoop1982], [rutherford1983])

  • Superficial, shallow root system with a more substantial system going deeper into the soil (bimorphic root system) [rutherford1982]

Phenology

Leaf flush

  • Takes place before the first rains.

Flowering

  • In Bushmanland October – November [leger1997]

  • Flowering takes place after leaves have been produced [childes1989] but does not seem to depend on rainfall. Flowers were observed on trees in the Otjozondjupa region before the onset of the rains in 1994.

  • As is the case with other savanna woodland species such as Schinziophyton rautanenii and Pterocarpus angolensis, the crop of flowers and subsequent may be reduced significantly by a late fire; flowers and leaves are scorched. During his studies at Nylsvlei, South Africa, [rutherford1982] determined see that flowering was also severely reduced for several years after a fire.

  • May produce flowers more than once in a single wet season [childes1984]

Fruit Production

  • Fruit may be parasitised to form clusters of linear, twisted brown structures that are very much unlike the normal fruit [bri1963]

  • Fruit may remain on the tree until the subsequent year’s flowers are produced.

  • Leaves abscise in early autumn [pendle1982].

Growth and development

Seed release and germination

  • About 1700 de-winged fruit per kg ([msanga1998])

  • With no treatment germination is low. Soaking in cold sulphuric acid for 30 min provides 25% germination ([tietema1992])

  • soak in cold water for six hours to soften endocarp and leach out inhibitors. Then germination 20% germination after 10 days, 60% after 30 days. [msanga1998]

  • best sown in situ (Drummond 1981)

Establishment

  • Seedlings are seldom found under the canopy of any tree ([yeaton1988], [scholes1993]).

  • Competition seems to play an important role in the spacing patters of T. sericea at Nylsvley, South Africa ([smith1986]). On the other hand, [shackleton2002] found little evidence of intra-specific competition using the same technique (nearest neighbour) in other areas of South Africa.

Growth

Radicle forms a tap root ([msanga1998])

The shallow root system permits the species to make use of water from light rains or heavy due.

Able to photosynthesise up to -27bar soil moisture availability ([smith1986])..

Vegetative propagation

  • T. sericea coppices persistently.

  • [teague1990] report that trees coppice and sucker readily even if ring-barked, or even after fire ([rutherford1981]).

  • Although most seed occur under the canopy of parent trees, more seedlings survive in open areas,  ([smith1986]).

  • When trees are cut, the amount of coppice shoots is related to stump size and cutting hight, with more shoots produced by larger diameter stems and when stems are not cut at low heights (20cm in the case of the trial reported on by [shackleton2001]

Uses

  • Wood is very hard, used for poles, implement handles, furniture ([leroux1971], [vanRooyen2001])

  • Reasonable as a firewood ([davis1991])

  • Bark strips used to make cord / rope ([vanRooyen2001])

  • Roots and stem bark used to cure stomach disoders & diarrhoea ([vanRooyen2001])

  • Infusions / decoctions from bark used to as eye lotions and to treat pneumonia ([vanRooyen2001])

  • Bark is used to treat diabetes ([vanRooyen2001])

  • Bark used to treat wounds ([vanRooyen2001])

  • Roots are used as an antimicrobial & to treat diarrhoea in Tanzania ([fyhrquist2002]

  • May cause significant reduction in carrying capacity when coppicing ([teague1990]).

  • May be browsed by cattle, especially young growth ([shackleton2001]). browsed by Kudu and Impala ([davidson1998]).

  • plays an important role in the nutrition of Tswana goads ([aganga2000])

  • Bark is heated and pounded into a sticky mixture that is used to make boats water tight ([leroux1971]).

  • Bark is used to append hair ([leroux1971]).

  • roots are used to treat diarrhoea & stomach ache ([leger1997])

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