Tree up to 4m high. The simple Leaves may have domatia. Attractive bisexual and zygomorphic Flowers are terminal. Distinctive purple lines internally on the petals. Fruit a club-shaped, dehiscent woody capsule.
RSA Tree No. 681.1.
Common names: Mackaya, Forest bush, Forest Bell-bush, bosklokkiesbos, River bell.
Family: Acanthaceae. (The acanthus family). This family has about 230 genera and 4 000 species. In southern Africa there are about 42 genera and 350 species. All members have simple Leaves without stipules. They are mostly entire. Inflorescences are mostly bracteate – subtending each flower. The Flowers are usually zygomorphic, bisexual with a nectariferous disc. The calyx usually shorter than the gamopetalous corolla, which has 1-2 lips. Usually 4 Stamens arising on the corolla are present. The 2-locular Ovary is superior and contains a large embryo. Fruit is 2-locular and Seeds lack endosperm. Local genera include Barleria, Duvernoia and Mackaya.
Name derivation: Mackaya Named after J.T. Mackay – keeper of Dublin University Botanical gardens and author of Flora Hibernica – “The Wild Flowers Plants and Trees Of Ireland”. bella – beautiful: referring to the flowers. Mackaya bella is the only species in the genus Mackaya.
Conservation Status: L C. (Least Concern). 2009.
Tree is small, up to 4m high. However, it is usually a multi-stemmed shrub. The Bark is pale greyish brown and longitudinally fissured on old stems. Between these dark grey ridges, the bark is light and spotted with red. In slender young branches the bark is lighter and smoother.
Leaves are simple (has a single blade which may have incisions that are not deep enough to divide the blade into leaflets), opposite, elliptic to lance shaped and up to 17 x 4cm. The Blade is wavy, dark green and glossy above but lighter green and dull below. The Midrib and side veins are raised and clearly visible below. They may also be raised above. Reddish purple hair tuft Domatia (tiny chambers produced by plants that house arthropods) may be found in vein axils (photo 982). The Apex is acuminate (said of an acute apex whose sides are somewhat concave and taper to a protracted point) and folded upwards into a drip-tip. The Base is narrowly tapering. The Margin is undulate (wavy) even crenate (shallowly round-toothed or obtusely toothed, scalloped). The Petiole (leaf stalk) is up to 1,5cm long.
Flowers are in terminal Monochasial cymes (inflorescence in which the main stem ends in a flower and bears, below the flower, a lateral branch which itself ends in a flower. This branch may in turn bear further similar branches). Flowers are bisexual and zygomorphic (irregular flower: when corolla is divisible into 2 equal halves in one plane only). Two Bracts are present. They are slender and taper to a point. 2 Bracteoles (secondary usually smaller bracts) are also present. Individual flowers are up to 5cm long. The Calyx is regular and hairy and the 5 Sepals are thinly and deeply lobed almost to the tubular base. The Corolla is bell shaped and not regular. The base is tubular below and becomes bell shaped prior to splitting into lobes. It has 2 lips. The upper lip has 2 Petals and the lower lip 3 petals. The corolla is an attractive, delicate pale mauve to white which form a tube up to 4cm long and from which extend the spreading lobes. The flower is up to 6cm in diameter. Veins on the petals are visible, especially the purple ones on the inside. There are 2 fertile Stamens which are attached to the base of the expanded section of the corolla tube, barely protruding from the top of the mouth. The purple linear Filaments end in Anthers that contain 2 long Thecae (pollen sacs) forming an inverted V-shape which is attached at the base of the V (photo 222). Two Staminodes (sterile stamens) are also present. These are mainly white and shorter with much fewer purple linear lines than the filaments. There is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma) with a superior Ovary that is 2-chambered with 1 or 2 ovules in each. The Style has 2 equal branches. (Aug-Dec).
Fruit is a narrowly club-shaped, woody Capsule (a dry fruit resulting from the maturing of a compound ovary with more than 1 carpel) up to 3,8cm long and supported by a short stalk. It is dark brown and dehisces into 2 valves which curl well backwards and eject the small seeds leaving behind the persistent Calyx. (Oct-Jan).
Distribution & Ecology
The Plants are able to survive in the forest shade up to an altitude of 2 000m. They occur naturally in the Eastern Cape Coast, close to the border with KwaZulu-Natal, KwaZulu-Natal, Mpumalanga, Mozambique and Limpopo. It occurs in Swaziland. Flowers attract carpenter bees. The larvae of the dark blue pansy Butterfly (with a characteristic large dark blue spot) Junonia oenone feed on the leaves.
Wood can be used to kindle fire by friction. This is a good garden plant and may develop from seeds or cuttings. The tree thrives in the shade but the most attractive flowers appear when situated with some sun.
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.