TREE LIFE

April 1986

 

MASHONALAND CALENDAR

Tuesday April 1st :  Botanic Garden Walk.

11 – 14th April : Mana Pools trip

Sunday April 20th :  Mpondaminga on Kilmacduagh Estate, Home of Mr. Lance Perry.  I well remember Mr. Perry’s farm as the first Tree Society outing I ever attended.  Since then I have been longing to get back to this rewarding stretch of the Great Dyke.  Mpondaminga overlooks the gorge cut through the dyke by the Maquadzi River and therefore has superb view and excellent woodland with unusual species. At this point the Maquadzi is also free from crocodiles as well as from bilharzias as the snails cannot tolerate the high metal toxicity of the waters.  After a morning along the river, lunch on the lawns, including a rapid swim for those so inclined, and a walk into the nearby hillside.  We will stop on our return journey to explore a small patch of swamp forest used for the filming of King Solomon’s Mines.  We have organized a bus departing from Monomatapa Car Park at 0830 sharp.  A security guard will look after the cars.

 

MATABELELAND CALENDAR

Sunday April 6th :  We will go to Northway Extension.  Meet at 0830 hours in Northway at the junction with Burnside Road.

Zanthoxylon capense. Photo: Bart Wursten. Source: Flora of Zimbabwe

Zanthoxylon capense. Photo: Bart Wursten. Source: Flora of Zimbabwe

On Sunday March 2nd we went to Mabukuweni and had a most pleasant outing.  We identified some 50 trees, only about half of what we know to be present, but, then we only investigated one side of the area.  These included :  Acacia gerrardii, A.karroo, A.nilotica, A.rehmanniana, A.sieberana, Albizia amara, Albizia antunesiana, Aloe excels, Azanza garckeana, Bridelia mollis, Burker africana, Commiphora mollis, stems not very square!; Commiphora schimperi, with leaves very small, Croton gratissimus, Cussonia natalensis, Erythrina latissimus, Euclea natalensis, Faurea saligna, this with unusually narrow leaves; indeed, much that we saw seemed smaller or narrower than the normal, if one may use such a term, either affected by drought, or by the very rocky surrounds, or both; Ficus glumosa, Ficus thonningii, Grewia flavenscens, Grewia monticola, Lannea discolor, Maytenus senegalensis Olea europea subsp. africana, Osyris lanceolata, Pavetta, gardenifolia, Pavetta schumaniana, Pouzolzia mixta, Pterocarpus angolensis, Pterolobium stellatum, Rhoicissus tridentata, Schrebera alata, Sclerocarya birrea, Securidaca longepedunculata, Sericanthe andongensis, Terminalia sericea, Turraea nilotica, Zanthoxylon capense, Fagara, Ximenia caffra, Ziziphus mucronata.

C.Sykes

 

BOTANIC GARDEN WALK, MARCH 1986 : THE ECONOMIC SECTION

Erythrophloem sivaveolens. Photo: Bart Wursten. Source: Flora of Zimbabwe

Erythrophloem sivaveolens. Photo: Bart Wursten. Source: Flora of Zimbabwe

It was a pleasure to investigate the Economic Section of the Botanic Garden as this has remained a mystery to most of us. Bob Drummond kindly researched the section for us and led an enjoyable walk
Apparently Tom originally planned a poison section and we saw the large specimens of Melia azedarach, Erythrophloem sivaveolens and Albizia versicolor.  This idea was then modified to include plants which are potentially of economic importance in Zimbabwe and these will be discussed in the order in which they are growing.  Dick Petheram kindly wrote the notes on Laucaena and Pochota and Barbara Browning helped with the grasses and in directing the walk.

Phyllostachus viridian, POACEAE, BAMBUSOIDEAE.  The fast growing young stems of this species are apparently free from acridity and may be cooked as bamboo shoots in Chinese cooking.

Actinidia chinensis, Theales : ACTINIDIACEAE.  The Chinese gooseberry or Kiwi fruit as it is termed locally is a woody vine that produces these familiar fruit.

Strophanthus kombe APOCYNACEAE.  The seeds of this indigenous creeper are deadly poisonous due to the cardiotoxic glycoside called strophanthis.  When extracted and used correctly it can treat heart ailments.  The same chemical can also be used to manufacture cortisone, a hormone that is usually secreted from the cortex of the adrenal gland and helps to relieve swelling.  This plant is common in the valleys of the Zambezi and Sabi Rivers and has spectacular flowers.

Phoenix dactylifera  ARECACEAE.   These date palms were grown from seed collected from Nigeria and were thought to be more suited to higher rainfall area.  Cheryl has successfully germinated seeds from packets of dried dates, although most palms needs to be planted very fresh as according to Prof Corner there is no dormant phase, the embryo simply grows very slowly.

Cyphomandra betacea  SOLANACEAE.  The tree tomato which fruits profusely in and around Harare.

Syzygium cuminii  MYRTACEAE.   The jambolan with larger fruits than our local wterberry.

Rubus nivens ROSACEAE.  The dusty berry.  This is a large genus that includes the raseberry, blackberry and loganberry.  Dustyberries self seed all around our garden and besides keeping the kids happy for hours they make a fine wine.

Spondias cytherea  ANACARDACEAE  These otaheits apples were just coming into fruit so we did not taste them.  Brian found an interesting reference to the related S.mangifera which stated it had a “flavor like that of an exceedingly bad mango”.  Apparently it makes an excellent preserve.

Coffee arabica  RUBIACEAE  and Camelia sinensis  THEACEAE  provide coffee and tea respectively.  The untrimmed tea plant showed its natural tree like habit, the trimming to bush form is only for better picking.  The flowers showed its resemblance to the Camelia we grow in gardens.

Cananga adorata  ANNONACEAE is cultivated for the scent of its flowers.  The distilled scent is called ylang-ylang or cananga and apparently 1 acre of trees may produce 3000lb of flowers or 15lbs of extracted essence.

Elaeis quineensis  ARECACEAE.  The West African oil palm that is being cultivated for a  plantation in the S.E. Lowveld.  These nuts yield two types of oil,  that from the outer covering is used in cooking and lighting, that from the kernel is used for margarine and cooking fats.

Bixa crellana  BIXACEAE.  This lipstick tree is a suitable garden subject with dark leaves and a crown of pink floers.  The seeds are covered with a crimson coat that yields annatto, a food colouring.

Olea europaea   OLINIACEAE.  The olive tree

Swietenia mahogany   MELIACEAE.  The mahogany

Averrhoa carambola  OXALIDACEAE.  It is very unusual to find a tree like this in the same family as sorrel, this species produces carambola, an edible fruit

Melpighia glabra  MALPIGIACEAE.  The Barbados cherry is grown for the high vitamin C content of its fruit.  We found a few ripe fruit and grimaced with the ascorbic acid level, do people enjoy them?

Murraya koenigii  RUTACEAE.   The compound leaves and gland dots reveal this plant’s family.  A number of fold were impressed with its aromatic smell, it is generally added to curry and may be purchased in town.  Some of us found the association too close to that of Clausena anisata, perdepis, to actually enjoy.  Although every now and then even a Clausena can smell like aniseed.

Jatropha circas  EUPHORBACEAE.  The black physic nut is used as a local medicine to cure many ills and has been widely distributed in Zimbabwe.  It grows around Diana’s Vow as a small shrub.

Aleuritis fordii  EUPHORBIACEAE.  The fruit of this Chinese tree yields an oil which dries and so is used in paint, varnish and linoleum.  It has been extensively cultivated in Malawi.

Hevea brasiliensis  EUPHORBIACEAE is the source of para rubber.

Manihot esculenta  EUPHORBIACEAE is the cassava.  These tubers all contain cyanide and generally need tobe cooked or dried in order to render them edible.  When the University’s bush was cleared out for building operations the workers rushed in and started eating them raw, despite my dire warnings.  They lived to prove me wrong and proclaim something about yellow petioles vs red petioles – I gave up.

Simmondsia chinensis  EUPHORBIALES, SIMMONDSIACEAE.  In spite of its Latin name the Jojoba comes from the western USA.  This bush has been hailed as a possible part solution to the petrol crisis.

Coix lachrymal – jobi  POACEAE.  This grass has seeds called the tears of Job and these are often used as rosary beads.  A thin shelled variety is prepared and eaten like barley.

Cymbopogan sitratus POACEAE. The lemon grass smells like lemon creams.  These oils are extracted and use to scent soaps or to manufacture the scent of violets as well as vitamin A, all these compounds are chemically related.  The essential oil in lemon grass can now be made artificially and so it is no longer extracted from the plant.

Pochota glabra  BOMBACACEAE.  The pichina nut, which we passed on our way to the jackfruit, obviously got its common name from Pachina glabra, which was for a time the botanical name of the bush or tree.  Prior to that, it was called Bombacopsis glabra, and before that, Bombax oleagineum – pointers to the fact that it is of the Bombacaceae family, as are the baobab and the kapok trees.  Its botanical name is now Pochote glabra.

Other common names are wild cocoa, see below, water chestnut and Guyana chestnut.  The last of these seems not inappropriate; it hails from S.America and the 10cm long, rugger ball shaped, hard shelled fruit splits open to reveal irregularly rounded seeds, each with its own thin brown protective skin.  These can be eaten raw or lightly roasted.  A trifle floury they seem to us, but pleasant.

The cocoa tree by the way, by name Theobroma cacao I believe at the time of going to Press, belongs to the related family STERCULIACEAE.  Judging from the literature, its fruit might be similarly shaped, but are appreciably longer.

Artocarpus hetersplyllus  MORACEAE.  The jackfruit in the garden have grown large and one tree is even fruiting.  These large fruit, up to 70lbs.have a pungent odour which Brian found described as “mawkishly sweet and mousy”.

Artocarpus altilis  MORACEAE.  This tree, responsible for the Mutiny on the Bounty, has a palmately lobed leaf and the fruit has an overpowering odour which is “not considered a drawback” by the locals.  Tom’s tree dies back each winter but is growing out once again.

Leucaena leucocephala. Photo: Bart Wursten. Source: Flora of Zimbabwe

Leucaena leucocephala. Photo: Bart Wursten. Source: Flora of Zimbabwe

Leucaena leucocephala  MIMOSACEAE.  Among the first of the plants we saw in the legume Leucaena leucocephala.  There are various strains of this species, as well as several species of the genus – which might make the whole subject of leucaena seem too complicated to bother about.  However, it is worth more than a passing thought, since it is being experimented with in numerous tropical and sub-tropical countries, including Zimbabwe, for its highly beneficial nitrogenous contribution to soils, its value as excellent forage for ruminants and in some forms and in some environments, its speedy growth into trees of a size suitable for firewood.  It can be used also as shade trees for plantation crops and as a source of dyes.

The very young seeds and leaves of this Central American plant are eaten by people in some rural areas of Central America and S.E. Asia, but the foliage contains an animo acid called mimosine and this can cause weight loss and ill health in non-ruminants.  Any tendency to indulge in such snacks to excess in the Botanic Garden should therefore be discouraged.  Ruminants have micro organisms that render mimosine harmless, so take your pet cow or goat along on a lead, if the urge is irresistible.

We must thank Bob for an interesting walk, there are still a few trees I missed out, such as the kapok, the carob and the raisin tree, next time I will be more attentive.

 

GLETWYN, HOME OF IAN AND BIDDIE ROSS : SUNDAY 16TH MARCH

Details of the AGM held on the lush lawns of Ian Ross’ homestead, on Gletwyn, will follow in the Minutes.  However, members should be advised of the officers elected as follows:

Chairman                             Kim Damstra                      Secretary             Sheila Weaver

Vice Chairman                   Marjorie Barker                  Treasurer            Joy Killian

Committee members :     Meg Coates Palgrave,    Georgie Granelli       Pat Walker        Margaret Bennett           Molly                                                   Kilpeert     Vida Siebert    Maureen Lumhoist-Smith       Philip Haxen

With little time left before lunch after our AGM members nonetheless ventured out like mad dogs and Englishmen in the mid day sun to see what of interest was to be seen on the low kopje behind the picnic site.

Strychnos cocculoides. Photo: Bart Wursten. Source: Flora of Zimbabwe

Strychnos cocculoides. Photo: Bart Wursten. Source: Flora of Zimbabwe

I first saw a fine Strychnos cocculoides, although bereft of fruit it was diagnosed by the characteristic curving branches and the three leaf veins emanating from the base.  The fire resistant corky bark determined the species.

Higher up the hill was an Erythrina abyssinica which we separated from E.latissima by its smallish leaves.  A number of Faurea speciosa were present and though not in flower, the marginal vein and somewhat broad leaves were sufficient to identify this.

A good deal of time was spent discussing textures of trees and how this applied to Lannea discolor and Pterocarpus angolensis.  The idea is that one is not looking to see how man leaflets the tree has, whether they are paripinnate or imparipinnate or indeed whether they are leaflets or leaves, but rather one throws it all in together and tries to get the “feel” of a tree.  One can develop this ability to a fine art until, like Tom Muller, one identifies trees at 120km/hr.

Heteromorpha trifoliate. Photo: Bart Wursten. Source: Flora of Zimbabwe

Heteromorpha trifoliate. Photo: Bart Wursten. Source: Flora of Zimbabwe

Kim told me that his party saw a number of sizeable Ochna schweinfurthiana and Turraea nilotica.  They also saw Heteromorpha trifoliate which performed very well by producing a distinct carrot smell from the crushed leaves, underlining their common lineage in the UMBELLIFERAE.

Another spectacle which caught my attention, despite baby/little girl’s determination to undermine my otherwise riveted concentration, was Uapaca kirkiana, mushanja or muhobohobo.  The sexes are on separate trees and this was most obvious as all the males were covered in dead flowers and in this area males appeared to be in a strong majority – viva Uapaca!

Next on the list was lunch, followed by the contrasting excitement of the afternoon jungle.

-J.P.Haxen

The afternoon walk on Gletwyn was most interesting.  We set out through typical Harare woodland with a tall grass under storey, past Uapaca and Brachystegia.  The Albizia amara were interesting as Anton Ellert observed that the young shoots are coated in yellow hairs, this separates it from Albizia harveyi where the young shoots emerge a darker brown.  We often have problems with these two species in the middle altitudes where they grow side by side.  And then we dropped down into a gulley with permanent water and here the vegetation changed, the tall white trunks of Celtis africana held their chlorotic leaves high above us and Syzygium quineense grow to stout trees.  The remarkable feature of these trees was the presence of numerous bright red pneumatophores, or “breathing roots”.  These grow from the low trunk and also grow vertically out of the mud in the river and along the river bank.   Each root has a slightly swollen tip and the cells inside similar roots in other plants generally have large intercellular spaces through which the respiratory gasses move.  Roots, like all living things, need to breath oxygen and excrete carbon dioxide.  When flooded the roots are starved of oxygen, CO2 dissolves in water easily and is usually less of a problem.  These breathing roots overcome the stress.  None of us had ever seen roots like these on Syzygium before, but we will look out for them in the future.

The second find was a group of indigenous tree ferns, Cyathea dregei.  Ian Ross assures us they were there when he was a child, and there is no record of them having been planted.  Apparently they do grow in local patches around Bulawayo, so this distribution is strange but not unique.  When we did the recce I was surprised by the small prickles on the rachis of each frond and immediately thought of C.manniana although these ferns are very much narrower.  Checking on the specimens in the Botanic Garden confirmed that C.dregei is also spiney but less so than C.manniana.  These ferns suffered badly in the past few drought years and all the large specimens died, leaving five foot stumps with their hollow centres.  Fortunately there are a number of youngsters that all look healthy.  The forest was overgrown with Jacaranda, Cidrella and Lantana but nevertheless a rewarding place to visit.  I am still amazed to think it is practically in the centre of town.  We are really grateful to Ian and Biddie for their generous hospitality and for allowing us to share their farm.

-Kim ST.J. Damstra

 

-KIM DAMSTRA  Chairman

 

 

 

Sterculia quinqueloba. Photo: Mike Bingham. Source: Flora of ZimbabweMimusops zeyheri. Photo: Bart Wursten. Source: Flora of Zimbabwe