General Info

This Tree with its smooth bark may reach 5+m high. The simple Leaf shape is various. The creamy-white Flowers are large, regular and solitary. The large, indehiscent Fruit is ovate.

Description

Gardenia thunbergia

Previous name: Gardenia verticillate.

RSA Tree No. 692.

Common names: Forest Gardenia, Wild Gardenia, White Gardenia.

Family Rubiaceae. (Coffee family). This family of dicotyledonous plants has in excess of 600 genera and about 13 000 species and members include trees, shrubs and herbs. Local genera with trees include Afrocanthium, Canthium, Coddia, Gardenia, Pavetta, Rothmannia and Vangueria. Leaves are simple, opposite or whorled and have interpetiolar stipules. Flowers are bisexual or unisexual. They are gamosepalous (a calyx whose sepals at least partly united) and Gamopetalous (united joined petals – at least at the base). Stamens usually as many as and alternating with corolla lobes. The Ovary is inferior. Fruit is a drupe, berry or capsule.

Name derivation: Gardenia – named after Alexander Garden, a Scottish doctor, physician and plant collector (1730- 1791). thunbergia – named after C.P. Thunberg (1743-1828) a Swedish naturalist who collected mainly plant specimens in South Africa from 1772-1775. He then moved to Japan. After returning home, he completed his Flora Capensis In 1813. This was a reference work in Latin on the South African flora.

Conservation Status: L C (Least concern). Assessment date: 2009. (Raimondo et al.).

Tree

The small Tree with its angular crown is usually up to 5m but may reach 7m high. The straight Trunk is and has a diameter reaching 25 to 40cm. Bark is whitish to pale grey and smooth. Branchlets (a small branch or division of a branch – especially a terminal division – usually applied to branches of the current or preceding year) are short and rigid.

 Leaves

This evergreen tree has thinly leathery, soft, glossy and simple Leaves. They are usually 3 but occasionally 4 whorled. The shape is variable and each is up to 15 x 10cm.  Leaves occur at the ends of branchlets. They are hairless and often elliptic (Oval in outline, being narrowed to rounded ends and widest near the middle). The Margin is wavy. The Apex ranges between being tapered and rounded. The Base is decurrent (leaf blades that partly wrap or have wings around the stem or petiole). The Blade is light green and the Midrib and lateral veins are conspicuous. Net veins are visible when the leaf is examined against a strong light (photo 352). Domatia (a tiny chamber produced by plants that house arthropods. To the naked eye the domatia appear as small bumps) occur in the axis of veins and are hairy (photo 401). The Petiole (leaf stalk) is up to 2,5cm long.

Flowers

The large, solitary, creamy white Flowers are and produced in large numbers at the ends of twigs and are up to 7cm wide. They develop in leaf axils. Unlike those in G. cornuta, the flowers fade to cream but do not turn yellow. The Calyx has Sepals forming a tube, which is cleft at one side and has a cluster of small leafy outgrowths. In the Corolla, the base of the Petals forms a white tube, which is up to 7cm long. This extends into about 8 lobes with rounded ends. These lobed extensions move out at right angles to the tube. Nectar is produced at the bottom of the tube and can only be reached by insects with long proboscis like the Hawk moths also called Sphinx moths. The thickish calyx makes it difficult for other insects to dig through the tube to reach the nectar. 8 Anthers are present which alternate with the petals and are epipetalous (born or arising from the petals). A single Pistil (a unit of the gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma) is present and the inferior Ovary has a single Style emerging from it. Pedicels (flower stalks) are usually absent. Flowers are sweetly scented – especially at night. (Oct-Mar).

Fruit

The indehiscent Fruit remains on the tree for a long time. The plant cannot disperse its own seeds. Unless eaten e.g. by elephants or picked, the fruits may remain on the tree for longer than a year. The shiny, woody fruit is Ovate (egg shaped), without ribs and up to 8+ x 3,5cm and is hard on the outside and very fibrous inside. The surface has whitish raised dots and is pale greyish green unlike in G. cornuta where it is bright yellow. The fruit is tipped with a persistent Calyx (photo 348). Fruit may be produced in large numbers. Seeds are contained within a pulpy covering (Nov-May).

Distribution & Ecology

This Plant is located along the east coast in evergreen forests, forest margins as well in the bushveld (a sub-tropical woodland ecoregion of southern Africa). It is found in the Eastern Cape, from North East of Port Elizabeth to Kosi Bay, KwaZulu-Natal, Mozambique and Swaziland. Rhino, elephants, buffalo and large antelopes like Kudu, consume the Fruit. The seeds can withstand passing through the intestine – resulting in dispersal. The transparent winged Coffee Bee Hawkmoth (Cephonodes hylas) larvae feed on the Leaves. The plant can withstand some frost and is drought resistant.

Ethnobotany

The tree is very slow growing. The Wood is very dense. It is yellowish, and even though it is very hard, it able to be bent without breaking. The wood is used for making buttons, implement handles, tools and small items. It is too small for much other use. Propagation is from seed or truncheons. Seeds are removed from the fruit with difficulty. Planting should occur soon after harvesting. This plant was introduced into Kew in 1773.

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.

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

Schmidt, S. Lotter, M. & McCleland, W. 2002. Trees and Shrubs of Mpumalanga and the Kruger National Park.

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

http://redlist.sanbi.org/species.php?species=1412-18

http://www.plantzafrica.com/plantefg/gardenthun.htm

https://en.wikipedia.org/wiki/Gardenia_thunbergia

http://www.kew.org/science-conservation/plants-fungi/gardenia-thunbergia-white-gardenia

https://en.wikipedia.org/wiki/Rubiaceae

https://en.wikipedia.org/wiki/Carl_Peter_Thunberg

https://en.wikipedia.org/wiki/Cephonodes_hylas