TREE LIFE

JANUARY 2001

A VERY HAPPY NEW YEAR TO ALL OUR MEMBERS AND THEIR FAMILIES

AS BEFORE PLEASE CONFIRM WITH ANY OF THE COMMITTEE MEMBERS THAT THE SCHEDULED OUTINGS AND WALKS WILL ACTUALLY TAKE PLACE. SEE THE BACK PAGE FOR PHONE NUMBERS.

MASHONALAND CALENDAR

Tuesday 2 January Botanic Garden Walk Meet in the car park of the Botanic Garden where we will meet Tom at 4.45 for 5pm. If there is a topic which you would like Tom to discuss please contact any of the committee members.

Early January (6^th – 12^th perhaps) A trip is being organised by Jonathan Timberlake in Bulawayo to visit a ranch in the low veld. If you are interested please contact Jonathan direct.

Sunday 21 January Graham and Jean Young have kindly offered their farm for our outing this month. Seddies Farm is in the Glendale area.

Bring your chair, and lunch etc. for a lovely day out of town.

Saturday 27 January Meet in the car park of the Mukuvisi Woodland at 2.30 pm for Mark’s Walk.

MATABELELAND CALENDAR

1 January 2001 There will be the traditional New Years Day party at the Timberlake’s, Please bring your own drinks and contribution to food. Please phone Gill Short 3241541 (h) or 65942 (w), to confirm and for organising food.

Early January (6^th – 12^th perhaps. See Mashonaland calendar.

2000 was the 50^th anniversary of the founding of the Tree Society, and now is a very good time to gather information in order to compile and record our history.

Please drop us a line, e-mail, or phone with any details that you can remember. Do you have any articles or photographs which we can photo-copy or perhaps you have some particular memories or anecdotes worth recording for posterity.

Please give it some thought, we would love to have contributions from all over Zimbabwe.

BULAWAYO BRANCH OUTING, 1^st October 2000.

There are some people who harbour misconceptions in their otherwise sensible minds. When conversed with, these people seem sane, rational and reasonable. Indeed, some members of Homo Sapiens even exhibit signs of the wisdom their specific name implies! But any suggestion about a subject that they don’t really understand, or what appears to be a plausible explanation for an apparent mystery, is welcomed, nay entertained, without doubt or question. The arcane is unassailable somehow, even if it happens to be a perfectly natural phenomenon.

Gardenia volkensii. Photo: Bart Wursten. Source: Flora of Zimbabwe

One such misconception concerns the Gardenia volkensii tree. I remember being told, many years ago, that if this tree flowered in Spring, a good rainy season was certain to follow.

Being by nature a Philistine, I reserved my judgement and settled down to observe, over as many years as possible, whether this assertion could be verified.

Now, some thirty odd years later, I have concluded that Gardenia volkensii, which used to be called G. spatulifolia, does indeed flower, perhaps as a result of, and AFTER good rains have been experienced. As it sometimes happens that these good rains occur in successive seasons, even in Bulawayo, it becomes true that they succeed the flowers of G. volkensii.

This conclusion is by and large, as there are other factors which must be considered. One of these is how much stress has been imposed upon the tree. Another factor is frost, and yet another, wind. The accessibility of underground water is an important contributor. There is a lapse of time between the end of summer and the next spring. The intervening winter changes people’s perspectives. Plants and animals do not forecast events. They react to a complex set of circumstances and frequently hear or feel things humans cannot.

Bulawayo Municipality’s Leopard Rock Nature Reserve is only a few miles from the area we visited in August. But these few miles separate two areas markedly different from each other. The reserve is on the banks of one of the Khami Dams, which was fuller than I have ever seen it. The granite outcrops became true kopjies. I learnt that this granite is in fact Cyanite. There is a gravel pit where it is reduced to chips for road-building. The variety and diversity of tree species was diminished greatly. We found only forty-six tree and six shrub species and others. There was a religious sect baptizing proselytes in the odoriferous water.

Gardenia volkensii was the dominant genus, and most of these trees bore blossoms. The pink peeling paper-bark Albizia tanganyicensis was also full of fluffy flowers. These two trees were visible from quite a long distance away, and brightened up a landscape still brown from the winter, although Terminalia sericea and Albizia amarawere beginning to show tender green new shoots.

Only the genus Combretum had 3 different species. Other genera were only present in pairs, but there were 4 figs. There were 37 different genera. The one unusual tree was a willow, Salix mucronata, which Anthon said was not often found in Matabeleland.

The chin-spot batis was still singing its nursery rhyme, but the white-throated sunbird added its trilling song. While the other members of the outing went off to see the dam I sat for over half an hour trying to see this little sunbird as it fluttered around. I never did.

Soon Eric returned without the others who had lost him. We tried vainly to dislodge an old seedpod from a Gardenia tree, and went back to the cars for refreshment.

After tea when all members had returned, we decided to revisit the Mopane woods housing the spectacular Aloe hybrids. The mopane trees were quite bare and the Aloe flowers had been replaced by seeds.

Anthon, once again, we thank you for your leadership and shared knowledge.

-NORMA HUGHES.

BOTANIC GARDEN WALK:7 NOVEMBER 2000

The subject today was the genus Brachystegia. The genus is an African one extending from W Africa to Central and southern Africa and just occurring out of the tropics at 25 S in Mozambique. To get an idea of its distribution I totalled the species by the countries recorded in Legumes of Africa – a Checklist (Lock, 1989). 36 taxa are recorded there from a total of 15 countries. The top 10 countries are shown in the box (in descending order).

The richest area comprises the countries of the DRC, Zambia and Tanzania all to the north and east of us. There are of course no records from South Africa and this information is consistent with the fact that the richest areas in Zimbabwe are in the north and east.

The same summary reveals that the most widespread species are boehmii and spiciformis occurring in 8 countries each, followed by utilis which occurs in 7.

What are the features of the genus? It belongs to the subfamily Caesalpinioidieae in the Leguminosae. The leaves are paripinnate with opposite leaflets and therefore lack a terminal leaflet,. The pods are dehiscent, often explosively, leaving behind a pair of twisted valves. Technically, the flowers are enclosed by relatively large persistent bracteoles (second order bracts). All species produce the spectacular spring flush of colour. Taxonomically, the genus is puzzling because of the tendency to hybridise.

Of the 7 species, three are well known to us from the watershed  areas: boehmii (mufuti), glaucescens (mountain acacia) and spiciformis (msasa). These will not be discussed further here except for two points.

Firstly, Tom mentioned that a form of glaucescens occurs in the lowveld in deep sand. This appears to have smaller and fewer leaflets than the normal form which is so reliably associated with rocky places.

The other point is the larger number of leaflets which occur in the stunted form of B. spiciformis which grows in the eastern highlands. These typically have more pairs (6?) than the normal 4 pairs around Harare.

Hybrids between glaucescens and spiciformis are common and may take many forms intermediate between the original parent species. They often occur where the rocky habitat meets open woodland.

Tom was not aware of any hybrids between boehmii and glaucescens or boehmii and spiciformis.

On next to the Escarpment brachystegia, allenii, which is similar to boehmii, and in Zimbabwe is confined to the Zambezi Valley escarpment. According to Coates Palgrave, allenii has typically 5 pairs of leaflets whereas boehmii has 13-28. Lyn Mullin had brought a leaf from a tree in Raffingora, quite well to the south of the escarpment, and this had 8 pairs. Coates Palgrave remarks that true allenii is rare in Zimbabwe and that most material is the hybrid between allenii and boehmii.

Brachystegia utilis (false mufuti) occurs in the north and east of Zimbabwe. The common name suggests a similarity with boehmii but it has far fewer leaflets.B. microphylla, (small-leaved brachystegia) on the other hand, another eastern districts species, has many more (25-55 pairs) of small leaflets. Hybrids between microphylla and spiciformis and microphylla and utilis have been reported.

Brachystegia manga (blue-leaved brachystegia) is a very rare tree with glaucous leaves and usually 3 pairs of leaflets which has been recorded from near Kanyemba.

Finally, there is Brachystegia torrei (Torre’s brachystegia), known for many years as “sp. no. 1” and only recently formally named. This has an unusual disjunct distribution occurring in the NE and SE of Zimbabwe.

Although it was actually not a good time to look at this genus in the Gardens, mainly because the leaves were just unfurling and were rather atypical, it nevertheless proved a very interesting discussion and review of the genus. Once again, our great thanks go to Tom for his expertise.

-MAHyde

SABLE VALLEY FARM – 19/11/00

On Sunday 19 November 2000, about twenty white war veterans, their families and general hangers-on invaded Sable Valley Farm, home of Rob and Val Wood, having heard that there was firewood to be had and good quality roses which could fetch a dollar or two each at Africa Unity Square. After helping themselves to tea and cakes, they wandered off to investigate the local kopje.

Lynn Mullin led the way with 3 Jack Russells at his heels, closely followed by Andy, white from his recent visit to the far north. Mark was declared the arbiter should there be any arguments about tree identity although certain

Democrats amongst the group felt there should be opportunity to appeal to the courts or have a hand count if decisions went against them.

Dombeya rotundifolia. Photo: Bart Wursten. Source: Flora of Zimbabwe

Discarded Strychnos spinosa fruit crunched underfoot. Dombeya rotundifolia was first to be discussed, with its star-shaped hairs visible under a lens. These are shared with other species in the Sterculiaceae such as Azanza garckeana and Sterculia quinqueloba, both of which were also present. Odorous Clerodendrum wildii and its relations were discovered although it was remarked that garden varieties seldom smell. Pouzolzia mixta badges were given to those who were able to correctly identify the Grewia monticolawhich was adorned with an orchid in flower.

The day allowed for numerous discussions on the difficulties of separating the various Terminalia species. Terminalia sericea was occasionally obvious by its appearance and “tweeling pigs” (peeling twigs), but many specimens shared features of T. sericea, T. stenostachya and T. mollis. Literature does note that some Terminalia species hybridise which could account for the confusion.

Brachystegia spiciformis (msasa) and Julbernardia globiflora (mnondo) were both present and everyone racked their minds to recall the alleged 7 features by which they can be told apart – the latter has small terminal leaflets, more leaflets, carries its pods above the canopy, has a hairy fringe on the leaflets, hairy pods and … a prize of Z$10 000 to the first person to correctly identify the remaining two features; answers on an envelope containing US$100 to Tsotsi Promotions, Box 1, Mvurwidona.

Dichrostachys cinerea saplings were evident but, in spite of their promise of colourful Chinese lantern flowers, our hosts vowed to get rid of them since they spread everywhere (no need to label them Lyn!). Many alien invaders were also present which will need attention – Lantana camara, Opuntia megacantha and friends, Agave spp., Psidium guajava (guava) and an unnamed cactus.

A number of Cassia abbreviata specimens were observed – this is the only remaining Cassia in Zimbabwe with all others having been reclassified as belonging to the genus Senna. They were accompanied by Lannea discolor, and large examples of Kirkia acuminata. A splendid Zanha africana shaded one side of the kopje and its potential for causing poisoning was mentioned although no hard examples were known of. It appears that the roots and bark contain a saponin which may have pharmacological properties. The roots of this tree are commonly used in traditional medicine in Zimbabwe for complaints ranging from headache and pneumonia through to pains of the abdomen and legs. As with many plants, it has also been used as an aphrodisiac.

Many other trees bore the scars of muti hunters. All figs (Ficus thonningii, F. sur, F. sycomorus) carried cuts from which the milky sap had no doubt been collected – used for sore eyes and cataracts and to encourage lactation, among other things. Strychnos spinosa had its bark slashed – the bark as with other parts of the plant probably contains alkaloids related to strychnine, although local species have not been investigated to the extent of Strychnos species in other parts of the world. Ziziphus mucronata was similarly slashed – roots are a more commonly used part of this plant for urinary and gynaecological complaints, but traditional practices vary from region to region and bark decoctions have been recorded in South Africa for chest diseases.

We were spoilt for choice in a rather small area – which suited Tree Society members with their rather sedentary habits. Ximenia caffra pretended to be a Flacourtia, Vitex payos showed off its remarkably striate bark, Commiphora africana and C. mollis vied for attention, Vangueria was hairier – than Vangueriopsis of course – Erythrina, Pappea, Grewia, Albizia, Parinari, Ozoroa, Allophylus, Pseudolachnostylis, Ormocarpum, Afzelia. The list was almost endless – well, around 80 species in total. It is little wonder that my mind was soon spinning and I had to sit down and watch dung beetles fight over fresh cow manure, before making their personal collection and rolling it off. Suitably distracted, I struggled to get excited about whether the acacia was A. karroo or A. gerrardii. However, I did marvel at Acacia amythethophylla (the suitably named long-leaf acacia) and the scarlet flowerhead of the Scadoxus multiflorus(formerly Haemanthus) whilst waiting for the others to convince themselves that it was time for lunch.

Our afternoon meal was enjoyed in the pleasant surroundings of the Wood’s garden, after which Andy and Astri had an altercation over who should be first to take a swim. As a responsible professional I felt I should help them to reach an amicable arrangement, but sadly they both lost their balance as I reached

them and were soon more concerned about who would be first out of the water. Rumours that I was responsible for their demise in any way are frivolous and should not be entertained. To assist them to dry off we took a short stroll to see a single specimen of Stereospermum kunthianum (“pink jacaranda”) which had smooth silvery bark, new leaflets and no flowers at the time. A small Swartzia madagascariensis was spotted by Maureen near-by; this plant is the subject of a disagreement between ZINATHA and the University of Zimbabwe and a university in Switzerland. The latter two have found an antifungal compound in the roots of Swartzia which is to be commercially marketed. ZINATHA is claiming that they first provided the Swartzia samples to UZ and should not have been left off the patent. The issue of biopiracy is rather complex but one has the feeling that this is a case of the horse bolting through the open stable door whilst a rolling stone spoils the broth which is worth two in the bush. Retiring once more to the farmhouse for tea and cake, we refreshed ourselves before returning to our respective haunts.

Many thanks to our hosts – I’m sure we’ll be back to abuse your hospitality.

Thanks also to Mark for his endless patience and gentle teaching to a pack of somewhat slow pupils.

-Douglas Ball

THE SHRUB COMMUNITY OF THE KALAHARI SANDS

A ROOTNOTE by Kim Damstra in TREE LIFE No.47 (January 1984) provides some insight into the value of the shrub community of the Kalahari-sand forests of northwestern Matabeleland:

John Rushworth, of the Department of Biological Sciences at the University of Zimbabwe, displayed some results recently that I thought bear repeating. He has been working in the Kalahari sands of Hwange National Park. “Large areas of deep, infertile Kalahari sand in western Zimbabwe are carpeted with a dense, woody, shrub community, one to four metres tall, and are often regarded as of little use to man or the larger herbivores.” As the name implies, the Kalahari sands consist of coarse particles. In fact, only about 2% is silt or clay. A rich soil of volcanic origin, also within the National Park is known as basalt vertisol, and contains 91% silt and clay. This difference is important because many nutrients that are washed away in sand will cling to the tiny clay particles, and therefore will be available to the plants. To sidetrack for a while, this is one reason why termitaria are often so rich in nutrients. The termites collect all the silt and clay from the surrounding area, and pack it into their nest. This helps change the nutrient status so dramatically that we cannot fail to notice the difference between the vegetation on the termitarium and off it. To get back to the Kalahari sands, they do have a low level of nutrients. But coarse sand does have an advantage – we usually use a high proportion of sand in seed trays to encourage rooting. Kalahari sand is an excellent rooting medium. Many trees develop an extensive root system in the 30-m-deep sands. The rain water is quickly absorbed into the sand, where it is available to the roots. Many of the trees are legumes, such as Baphia massaiensis subsp obovata [jasmine pea], Acacia fleckii [blade thorn], and Baikiaea plurijuga [Zambezi teak], and can increase the nutrient status by means of nitrogen-fixing bacteria in their roots. Other Kalahari-sand plants, besides these, can also fix nitrogen. Dr Rushworth investigated the availability of food to animals during various times of the year, especially by comparing grasses and woody shrubs. He found that at the height of the dry season, before the rains, the deep-rooted trees flushed out in new growth that had a moisture content of 68%, compared with the grass water content of 20%. There was also much more browse available. The crude protein of the perennial grasses at this time of the year ranged from 4% to 6%, whereas in the shrubs it ranged from 19% to 26% – rather significant. The one exception was Lonchocarpus nelsii[Kalahari apple-leaf], which had 39% crude protein in the leaves in September. “Of the plants listed, Terminalia sericea[silver terminalia] and Baikiaea plurijuga [Zambezi teak] are not as favoured by the wild herbivore browsers (including elephant, giraffe, eland, kudu, impala, steenbok, and duiker) as are the remaining species (Baphia massaiensis, Bauhinia petersiana subsp serpae, Combretum collinum, Pterocarpus angolensis, Combretum zeyheri, Lonchocarpus nelsii, and Ochna pulchra). Bearing in mind the high quality of this leaf material, a good stock of valuable food is available in this shrub community, particularly during the dry August-November period when the grass layer is low in both quality and quantity.” John goes on to conclude: “The high quality of woody-shrub leaf material produced under arid conditions on infertile Kalahari sands in western Zimbabwe is nothing short of remarkable. Many wild herbivores, particularly the browsers, thrive on this source of high-quality food available in large areas of the Kalahari-sand region of Hwange National Park. Provision of permanent water supplies is often the only management aid required. It is apparent that there are vast untapped stores of valuable food available in the leaves of many woody shrubs of the `bushy/scrubby’ areas of Zimbabwe for both domestic and wild herbivores. Simple management practices can make much of this food energy available, particularly during the critical, dry, August-November period when natural grass stocks are low in both bulk and quality. The discovery that two apparently “useless grazing grasses” (Eragrostis spp) play a role in vital atmospheric-nitrogen fixation must surely make one more hesitant in the future to arbitrarily proclaim that any particular plant is of no use. We often know so very little about the life histories and real value of our indigenous plants. The woody species of the Kalahari-sand shrub community appear to represent equilibrium species, expending energy in the building up of massive underground rootstocks or other storage organs, which give the advantage in long-term survival. This particular ecosystem is markedly resilient to above-ground damage, and it represents both a very stable and valuable resource”. Quotations from Rushworth, J.E. (1978). Wankie National Park Notes No.20: 8 pp.

PAPER AND PAPERMAKING

(Adapted from an information sheet produced by Hunyani Paper & Packaging (Pvt) Ltd)

History

According to tradition paper was first made in China in 105 AD by Ts’ai Lun, a courtier of the Emperor. Formerly people wrote on strips of wood, or silk, or on papyrus bark, but from that date Chinese history and records were written on scrolls of paper. The earliest paper that still exists was made from rags, and dates back to 150 AD. Paper from China arrived in Egypt at the end of the 8th century, and from there the Moors introduced it into Europe. Printing was also invented in China, spreading to the rest of the Orient in the 9th century, and thence to Europe. This ability to produce multiple copies of the written word, graphics, and pictures in a mechanical way was – and still is – an important reason for the continuing high demand for paper.

Paper-making Materials

Paper comes from vegetable materials, which contain cellulose fibres in their structures. These are first reduced by chemical and mechanical energy into their component fibres in a process called `pulping’. Wood is the most common material used for making paper, but sisal, hemp, bagasse, and even wheat and maize stalks will do.

In Zimbabwe we use four different types of material for making paper. At the Hunyani Mill at Norton the wood of eucalypts is the main material for pulping, along with a smaller amount of wood from pines. Chips of these woods are heated to high temperatures in mixture with sodium sulphite, and `refining’ or mechanical energy is then applied, producing a `semi-chemical’ pulp. Eucalypt pulp is ideal for making fluting, the very stiff centre ply of a corrugated cardboard box.

At Kadoma Fine Papers cotton linters (a waste product from cotton processing) are heated with caustic soda, followed by bleaching with peroxide, to give a fine cotton pulp to be transformed into a very desirable white printing and writing paper.

At Mutare Board & Paper Mills debarked pine logs are processed by pressing them against rotating grindstones in the presence of hot water. This process consumes a lot of energy, and produces `groundwood’ pulp, which has excellent properties for making newsprint and folding boxboard.

The Kadoma Tissue Mill, and the mills at Mutare and Norton, also use large amounts of recycled paper as important parts of the various grades of their paper products. The waste paper is collected throughout Zimbabwe, sorted into different qualities, and distributed to the mills.

Papermaking

The pulp fibres are well mixed with water, and the suspension of pulp is filtered through a fine sieve or screen, leaving the fibres in the form of a sheet. In earlier times paper was made by hand in sheets, using rectangular sieves, but in 1803, in England, the Fourdrinier brothers developed a commercial paper machine from the design of a French inventor, Nicolas-Louis Robert, of a continuous machine using an endless wire mesh. The same type of maching is still widely used, although the `wire’ mesh has now been replaced by plastic, and modern machines are much faster than that early invention. Indeed, of five of the six papermaking machines in Zimbabwe are `fourdrinier’ machines.

The Uses of Paper

The single largest use for paper is in printing. Newspapers, books, periodicals, brochures, forms, leaflets, labels, duplicating, and computer printout are just some of the many purposes for which paper is printed.

Packaging is also a very large consumer of paper. Corrugated cases, cartons, bags, sacks, and wrappings are important for holding goods, for transporting them safely, and for informing the customer of the contents. Very often the packaging will have attractive printing on it.

Tissue products made from paper and fluffed wood pulp are a growing market worldwide. This creped paper gives us toilet tissue, facial tissue and towels, and a variety of other hygienic products.

It is often said that the consumption of paper is a good indicator of the state of development of a country, and indeed there is a strong relationship between the two. The United States of America, one of the most developed countries, has an annual consumption of 320 kg of paper per head, whereas South Africa consumes 44 kg per head, Zimbabwe 11 kg per head, and our neighbours in Zambia a little over 1 kg per head.

The Environment

The paper industry is well aware that its activities, if not well controlled, could cause damage to the environment. It is thus mindful that, if it is to prosper in the long term, it must foster the sustainability of its resources, and have a genuine care of the environment. There have been numerous cases in the past of pulpmills polluting rivers and water supplies, but today this is most unlikely to happen.

Paper Production in Zimbabwe (1997)

Hunyani Pulp & Paper, Norton – 50 000 tonnes
Mutare Board & Paper Mills – 31 000 tonnes
Kadoma Fine Papers – 8 000 tonnes
Kadoma Tissue Mill – 5 000 tonnes

-Lyn Mullin

Please continue collecting seeds for Ann Bianchi. In particular she needs seeds of Heteropyxis dehniae, Sterculia rogersii and Croton pseudopulchellus

ANDY MACNAUGHTON   CHAIRMAN