TREE LIFE

December 2003/ January 2004

THE CHAIRMAN WISHES ALL MEMBERS OF THE TREE SOCIETY AND THEIR FAMILIES A VERY HAPPY CHRISTMAS AND A BRIGHTER 2004.

 

FROM THE ABOVE DATES YOU WILL HAVE NOTICED THAT THIS ISSUE OF TREE LIFE COMBINES DECEMBER AND JANUARY AND WILL BE A LITTLE LONGER THAN USUAL. THIS IS BECAUSE MARK AND MAUREEN WILL BE VISITING OTHER PARTS OF THE WORLD DURING MOST OF DECEMBER.

 

MASHONALAND CALENDAR

Tuesday 2nd December. Botanic Garden Walk. Meet in the car park at 4.45 for 5 p.m. The topic will be the family Flacourtiaceae.

Sunday 7th December. This will be our Christmas Social and once again Bill Clarke has invited us to his lovely property Val D’Or in the Arcturas area. Adele and Rob have compiled a quiz which should be a lot of fun – there will be prizes. As is usual at  these Christmas functions we invite members to bring something to share for tea.

The program hasn’t been finalised yet, but lunch will probably be after the quiz and in the afternoon we could take a walk in the woodland.

Saturday 27th December. As Mark will be away there will be no walk on the fourth Saturday.

Tuesday 6th January.  Botanic Garden Walk. Meet Tom in the car park at 4.45 for 5 pm.

 

MATABELELAND CALENDAR

Nothing has been arranged for December.  For details of the traditional New Year get-together in Bulawayo please contact Jonathan Timberlake.

 Welcome donation from PG Industries

Earlier in the year I wrote to a number of local companies asking on behalf of the Tree Society for donations to enable it to continue functioning and to carry out its various projects. We have now received a donation of Z$50,000 from PG Industries. This is the first successful response we have had. We are very grateful indeed for this sum, which has strengthened our financial position and will help somewhat to ease pressure on member’s subscriptions.

Thank you, PG Industries!

Mark Hyde

 

BOTANIC GARDEN WALK: 4 NOVEMBER 2003  Albizias, continued …

Tom once again tackled the question of Albizias. We looked again at some of the same species which had been rushed last time and saw some we didn’t see last time. Maureen had kindly provided photocopies of the write-up of the previous walk and this was helpful as it enabled us to look up each species in its group. In each case, we recorded the position of the petiolar gland, expressed as a % of the petiole length from the base of the petiole.

Albizia harveyi was dealt with rather superficially last time. A very important character is the very rough bark; this was particularly striking on a specimen we saw near the restaurant but in fact less so on the first tree we examined not far from the car park. The leaflets are slightly sickle-shaped (falcate) and the pinnae are some way apart  features which separate it from the much commoner Albizia amara. It occurs in both riverine and woodland habitats in the lowveld and also ascends to higher altitudes in alkaline soils. The gland was high on the petiole, c.60-80% of the petiole length.

Albizia brevifolia could not be found last time, but several small trees were found on this occasion. The trunk and larger branches bear lateral spurs with a swollen base which look a bit like Commiphoras. Leaflets are very small and the pinnae are widely spaced. The gland is at about the mid point of the petiole. This is a low altitude species and occurs on the schist belt at Kariba and commonly on kopjes around Hwange.

Albizia amara has relatively short stamen-filaments; the clusters of flowers really do like shaving brushes. Digressing, Tom mentioned that he only owned three high quality items: a badger-hair shaving brush, a hairbrush made out of Siberian wild boar hair and handmade crocodile leather shoes. The pinnae are close together (already mentioned in the comparison with harveyi) and the bark is rough (like harveyi). The gland is at about 1/3rd of the way up the petiole. It is a very common species at both high and low altitudes, often occurring in woodland.

We next viewed the very large specimens of Albizia gummifera in the Garden. These are very fine and were covered in flowers � but all were way out of reach – and no ladies volunteered to climb them. Noticeable features of this species are the smooth bark and the reddish flowers in the centre.

Similar to A. gummifera is Albizia adianthifolia. There is no specimen in the Gardens but Tom listed the features which distinguish it from gummifera, namely the rough bark, the absence of a heel on the leaflet and the hairy leaves.

Again we looked at Albizia antunesiana; the petiolar gland is exceptionally large and right at the very base of the petiole.

Albizia versicolor. Photo : Bart Wursten. Source: Flora of Zimbabwe

Albizia glaberrima. Photo : Bart Wursten. Source: Flora of Zimbabwe

Albizia glaberrima is a lowveld, riverine species. The pinnae have the largest leaflets at the apex and their arrangement is a bit like duiker footprints. The gland was between 1/3 and  the way up the petiole. Although this species does occur in the Zambezi it is not common there; its greatest frequency is in the SE of the country.

Albizia versicolor was in full flower and looked very beautiful with its large flowers raised above the leaves. The gland position was relatively low: 20-25%.

Albizia petersiana has a characteristic red flush in December. The gland occurs at halfway.

Albizia forbesii has tiny leaflets; it is a species of triassic sandstones in Gonarezhou. The gland is in a high position at c.70-75% of the petiole length.

Acacia grandicornuta. Photo: Meg Coates Palgrave. Source: Flora of Zimbabwe

Acacia grandicornuta. Photo: Meg Coates Palgrave. Source: Flora of Zimbabwe

In addition to Albizias, our attention was caught by some striking species in flower. A bush of Gardenia resiniflua (gummy gardenia) was covered in white flowers. Tom mentioned that this is another lowveld species which is a one day wonder, so we were I suppose lucky to catch it. Certainly, although I’ve often seen the species in the wild, I’ve never seen it flowering before.

The deep yellow spherical clusters of flowers of Acacia grandicornuta, arranged in long spike-like panicles flowers, were very striking.

Finally in darkening conditions, we came across the strange, dark, liver-coloured flowers of Monodora junodii.

As usual, we saw an enormous amount of interest and our thanks go to Tom for continuing to provide this wonderful service to the Tree Society.

 

 

Mark Hyde

 

TREE SOCIETY VUMBA TRIP: AUGUST 8TH – 12TH, 2003

The Tree Society visited the Vumba (sometimes called the Bvumba) mountains over the Heroes weekend. This was a difficult trip to organise (and I speak with feeling as the main organiser – at least at the Harare end) mainly because of two problems, namely the severe fuel shortage and the shortage of cash. Fortunately, John Bennett came to our rescue. He not only sorted out accommodation for us in the Vumba but he also arranged for his employer to provide some fuel for us to enable us to get back to Harare and also was able to assist with cash when time came to settle our bills. On behalf of the Society I would like to thank Chris Donald of GMS for supplying the fuel.

Friday August 8th

We travelled up in rather grey weather, stopping briefly at Halfway House near Headlands. On arriving in the Vumba we drove straight to John Bennett’s cottage where we arrived in the early afternoon and had a late lunch. We then identified a selection of trees which John had collected near his cottage. John has written about these together with other observations about the Vumba:

 

TREES ON FRESHWATER, VUMBA

My move to Manicaland was prompted at least as much by my fascination with low altitude areas as with mountains. I had not seen myself settling in the mist belt of Vumba, at an altitude scarcely below that of Harare. If the Albizia gummifera (schimperana?) canopy represents the crowning glory of complex forest systems responding to abundant moisture, I was stopped in my tracks on a recent visit to the lowveld, by that dramatically different Albizia tanganyicensis. For me it reflected the stark beauty often distilled under conditions of extreme stress. This was the real Africa, and Vumba the priceless exception that proves the rule.

On the Heroes holiday trip to Vumba the most concentrated learning curve for me was in the first 15 minutes. On the morning before the group’s arrival, I had collected about 17 leafy specimens from plants with which I had become familiar. Meg explained these, all forest outliers, common in the grassy to wooded areas between Eden Estate and the mountain.

Cussonia spicata was confirmed, the gnarled old man of both the fire- and mist-swept slopes and of the wetter, grassy hollows. My heart lifted recently when I noticed that a Cussonia, decapitated by a toppled wattle and deprived of all foliage, was sprouting a new rosette of leaves from the top of its spindly neck after 2 or 3 months. (Whether the wattle sprouts again is an altogether darker and more tragic matter.)

Another inhabitant of more exposed places, and a remarkable fire survivor, is Vangueria apiculata. It is never very large, angular in form, and its bark has a deeply reddish hue  its sparse leaves unmistakably of the Rubiaceae family.

Syzygium cordatum is at the opposite end of the scale  an abundant and large tree marking all the wetter spots outside of the rain forest. I was struck when we visited the Bunga Forest, about 200m higher, by how dominant and massive this Waterberry is, its leaves showing distinctly red, within the top level of the forest.

A multi-stemmed Sapium ellipticum grows out of the edge of a steep gully near where I hope some day to build a house. It provides useful hand holds when you need to descend to your dog caught in a snare set along the stream. It has characteristically drooping branches and black-stained undersides to its leaves.

Morella (Myrica) is a smaller tree, occurring across all the habitats. It has a markedly light-coloured bark enclosing a puffy stem, but its leaves are hardly serrated and with no trace of yellow, so presumably ruling out M. serrata. (M. pilulifera?) I find it a shapely tree, probably because I like trunks. Like Ochna, the leaf mid-rib is prominent above and below. Ochna holstii, with translucent, thin leaves and yellow flowers, is common on the edges of the forest.

Among the shrubs and herbs that will probably not be described elsewhere, as we visited only the rain forest, are Aeschynomene nodulosaa legume with colourful orange flowers, and Harungana madagascariensis, both so numerous that I didn’t mind sacrificing them when choosing a road in. Any aloe or Tetradenia riparia in the way were transplanted. Rhus chirindensis was displaying its new, red tri-foliolate leaves. Gymnosporia (Maytenus) senegalensis has leathery leaves and fearsome spines reminiscent of Dovyalis caffra. Toddalia asiatica is the name given to a pungent green climber, with small thorns that visciously attach themselves to your skin and clothes.

No Tree Society visit to Vumba can gloss over the extent of contamination by alien flora. Intolerance of course is one of the less endearing of human traits (especially among others!) But alien here refers to much more than an occasional ill-judged siting of a bougainvillea or jasmine. A Vumba alien could as well be the lowveld flame Combretum (paniculatum subsp. microphyllum). All are about as thoughtful as putting a moustache on the Mona Lisa. Now theres a thought. I must see whether the forest flame Combretum (subsp. paniculatum) can rein in the rampaging guavas!

Emotional diatribes are unlikely to cut much ice with apologists for exotic invaders. So I took some measurements. I have discovered a re-growth rate of between 5% and 95% on wattle stumps axed within the last 5 months. Attempting to de-bark re-sprouting stumps while standing waist deep in fallen logs is frustrating. But I feel this is a fray that one enters with a chance of eventual success. A few hours with a bush knife every week-end for the next 10 years?

My skirmishes with Flowering Cherry however are decidedly unequal. Every axed stump now sports between 20 and 120 new shoots, some of them taller than me after only 8 or 9 months. Infested areas comprise some 150 stumps per 100 sq.m. A typical area, 2m in radius will have 19 cherry trees, 2 each of Ochna holstii and Clausena anisata, plus a Gymnosporia senegalensis, guava and something else. From a distance the area now looks like a diverse and mature woodland with Bridelia micrantha in its russet colours, Erythrina, Morella (Myrica), Albizia gummifera, and others. But I have no doubt that in a few years these will have been obscured, as they were a year ago, by a blanket of merrily twinkling cherry leaves.

Suppressing the temptation to use an expletive, I would describe that rate of growth, as unnaturally rapid. Anyone needing convincing that stumping a mature Cherry Tree is an altogether more daunting prospect than stumping a mature guava, is welcome to visit Freshwater any time. I can provide picks, shovels and axes. It is curious that cherry is not regarded as such a menace a mere 200m higher up or lower down.

So why not bow to the inevitable? Accept that land has to pay its own way? That what has once been put to Eucalyptus grandis, is forever after disturbed, and should be retained for commercial uses, leaving one to concentrate on preserving the pristine areas? That if woodlots had been created within walking distance of Sakubva, the miombo woodland in the lower Vumba might not now be disappearing daily into town as firewood.

But it was not rational analysis that fired up the imagination in the first place. Was it Pascal who wrote something along the lines that, The heart has its reasons, that reason alone cannot comprehend. Logic may be necessary to win over the sceptics. But the pity of seeing our wildernesses being diminished before our eyes as invaders march across the landscape, is something you either see and feel, or you don’t.

It does raise the interesting question, why has natural selection not produced any local species possessing a fraction of that vigour?

-John Bennett

 

Saturday August 9th and Sunday August 10th Meg Coates Palgrave has kindly written up the next two days.

The nice thing about being asked to do a write up for a trip is that it enables one to relive the experience and our trip to the Vumba was one certainly one worth reliving. Poor Werner who broke his leg on the third day may feel rather differently. We all wish him a speedy and full recovery. When I have been to the Vumba in the past I have come away feeling a little frustrated that I have not been able to identify as many trees as I would have liked to, particularly those in the family Rubiaceae and so I was determined to concentrate on them when I saw them. And I have been able to name all that I brought back but one.

Mark, Werner, Gill and I stayed in a cottage and were joined by Liz and Tony for a meal most evenings. John who had initiated the trip lives in a cottage not far away and that was where we gathered each morning and were joined by Bart and Petra and Tackie from the Vumba and Pat from Mutare. So we were a fairly small group, happy to be sharing our interest in plants.

Polygala virgata. Photo: Bart Wursten. Source: Flora of Zimbabwe

Polygala virgata. Photo: Bart Wursten. Source: Flora of Zimbabwe

The first morning Roger also joined us and so we decided to take the opportunity of his presence to explore his bit of forest just beyond Eden Lodge which is just a few kilometres along the Essex road. Where we stopped in an open spot, in lovely purple flower, were Polygala virgata, happily also known locally as the pride-of-manicaland or manica-pride. And then we were into the forest. We started with a little familiarisation of some of the understory, species we were to see over and over again. I keep saying all trees have labels on them telling us what their names are. All we have to do is learn to read the labels. Teclea nobilis, giant cherry-orange, has a compound leaf with three leaflets, they smell quite strongly when crushed and translucent gland dots can be seen when a leaf is held against the light. This belongs to the citrus family and those translucent gland dots contain the citrus oils as does Clausena anisata, maggot-killer with pinnate leaves and a very pungent smell. We wondered if it really smelt like aniseed or whether the Afrikaans name, perdepis translated as horse urine might not really be more appropriate. I was quite excited to seeKeetia gueinzii, climbing keetia, with the leaves subtending the branchlets smaller and almost round, very different from the main leaves.

Peddiea africana. Photo: Bart Wursten. Source: Flora of Zimbabwe

Peddiea africana. Photo: Bart Wursten. Source: Flora of Zimbabwe

This was something I had recently read about and there it was demonstrating the label for us. Mark showed us how we could always recognise Peddiea africana, green-flower tree, a typical forest species with shiny green leaves. When a piece is picked the bark strips off. We found some green-flowers, very sweetly scented, they revived and lasted quite well in water. Later on in the weekend we were to discover that this has another label without having to resort to tearing off bits and pieces. It is obviously the food plant of some insect which eats nice little rounds off the leaf surface leaving bare patches. This was particularly obvious at higher altitudes in the Bunga and Castleburn forests where we could just spot the dot as we walked along.

There was a species we saw which we came across during our trip to the Honde Valley last year, the wild ginger, Aframomum albiflorum, also known as Madagascar cardamom. In the Vumba forests unfortunately there is a look-a-like alien, Hedychium, also a member of the ginger family Zingiberaceae, which really is becoming quite invasive. I get very upset about alien plants when they become invasive just as the wattle and the pine have done. Those two are obvious but there are others that seem to have crept in almost unnoticed and are more or less accepted as being naturalised and acceptable, as unfortunately this is becoming. It is quite attractive when in flower, as is the wattle. One of the differences between the two genera is that Aframomum bears its fruits on the ground and Hedychium bears the fruits at the ends of the stems. We eventually found some uneaten fruits of Aframomum. They are red about 5 cm long with seeds in the middle. I enjoyed the spicy flavour of the seeds when sucked but others found it not so pleasant.

Forests are often full of twiners and climbers and monkey-ropes one of which was a Landolphia. With a milky sap and opposite shiny green leaves with a wavy margin was, as I have since worked out, Landolphia buchananii, apricot-vine. The difference between this and Landolphia kirkii, sand apricot-vine which we saw the next day at a lower altitude, I have read about but not really seen or understood before, but now that I have the leaves of both species to compare, I can see the difference. Firstly Landolphia buchananii is a species of higher altitudes and secondly the lateral veins and net-veining are finely indented (valleys) on the upper surface forming a net-work of shallow cracks. On the under surface the lateral veins are visible and slightly ridged but the net-veining just looks a darker green. Landolphia kirkii on the other hand has very distinct pale greenish cream net-veining flat or slightly raised on both surfaces. I must confess to having to use a lens to see that detail. A milky sap and opposite leaves in the tree world usually indicates that the tree belongs to the family Apocynaceae as does this genus. The other interesting member of Apocynaceae we found later in the Bunga and Castleburn forests was Strophanthus speciosus, forest tail-flower. I was surprised to see it there, there are no specimens from the Vumba area in the Herbarium, but this is one of species that can’t be anything else. It has a milky sap and leaves are in whorls of three and again using the lens there are three tiny overlapping scale-like glands on the inside of the bottom of the petiole.

Another liane which I have never come to grips with before is Tiliacora funifera, appropriately called elbow-leaf because the petiole has a swelling and is bent just before joining the leaf-blade. The leaves have quite a long petiole and three distinct veins starting from the base.

There was a tree with leaves spirally arranged with toothed margins which was coppicing freely from the base sending up long shoots. It’s name did not jump into my head immediately but I was sure I should know it and would come up with a name after lunch. That I was not able to do. What I was thinking of was Aphloia theiformis, albino-berry which coppices in a very similar fashion and which we also saw. So as I write this I am afraid that is still a mystery tree.

The characteristics of Rubiaceae are opposite leaves (in pairs) with entire margins, and with a ridge going across to the opposite petiole with a distinct stipule. One we saw and collected that morning was Rothmannia urcelliformis, forest rothmannia. It did have its label, what I describe as the odd third leaf or a single extra leaf in the axil between two shoots. At the time I wondered if the leaves were too hairy to be the forest rothmannia. We saw it again in the Bunga forest, this time with fruit and there was no mistaking those hard round fruits about 5 cm in diameter which take two years to develop and ripen after flowering.

Someone once asked why the Tree Society always looked at small things and I seem to have concentrated on those, but let me assure you we were in forest with the canopy high above our heads. To see the leaves we needed to use our binoculars and that is very neck-straining when there is so much to see at more or less at eye-level. We walked under a liane with aerial roots just like those of a fig, a liane whose leaves could not be reached but through the binoculars they looked rather like those of a Rhoicissus probably Rhoicissus rhomboidea, glossy grape, or as someone suggested ropewood grape could be a good name for it. Mark later found some leaves at reaching level for me to see. They certainly are very different from the familiar Rhoicissus tridentata, bushman’s grape. Both species are essentially climbers and have tri-foliolate leaves, the lateral leaflets have a very asymmetric base and the midrib going up one side instead of being in the middle, but the ropewood grape has leaflets with a pointed apex and the margin with up to six distinct teeth each up to 2 mm long and sticking out. The leaflets of the bushman’s grape have leaflets with a square to rounded apex and 3 to 18 teeth, each tooth ending in a thin point.

And then we reached a proper fig, a huge strangler with aerial roots from the branches as well as the trunk, roots often reach the ground and form pillar roots so that they sometimes look as though they are propping up the branches. This was a really big one which we decided must be Ficus rokko, rokko fig. This species was part of the Ficus natalensis complex of the first 1977 edition of Trees of southern Africa and part of theFicus thonningii complex of C.C. Berg in Flora Zambesiaca but is now happily and distinctively recognised as its own species being very much a tree of forests and forest edges. What separates this from the other forest species of fig is that the others all have leaves with a distinct pair of lateral veins starting at the base and this doesn’t.

After lunch back at out cottage we made out way to the forest below Eden Lodge, one which I have had the pleasure of exploring before. I missed the path I had meant to take so we went right through the forest and then came back along the planned path in the opposite direction to the one I had originally intended to take. I was actually glad about that because to me the highlight of the afternoon was a group of spiny tree ferns, Cyathea manniana and that group is much better viewed from the side we did eventually see them than if we had approached from the other side. On the bank just above the spiny tree ferns was a Myrianthus holstii, reported as having leaves that fall with an audible plop. Having come upon the tree ferns which were a lovely sight, slender, several metres tall and often in groups and the sun just touching some of them and there was quiet for a few minutes. A couple of people were taking photos, the rest of us just enjoying the magical scene until Gill asked if we were all waiting to hear a Myrianthus leaf fall with its audible plop. Much laughter. We didn’t hear that but we did see the surrounding vegetation festooned with fallen leaves. These are digitate with five to seven large leaflets, dark green above and much paler to almost white below.

Previously we had seen another tree fern which I had always assumed to be Cyathea dregei, the common one or grassland tree fern with which we are all familiar. Someone said they thought it was Cyathea thomsonii, Thomsons tree fern. I was the original disbeliever in no uncertain terms as I was so sure that that was so rare I would never ever see it and frankly I had even wondered if it really was different from Cyathea dregei. By the end of the four days I had been convinced that it could indeed beCyathea thomsonii and I had seen it several times and that the two species are different and distinguishable. There are several reasons. This one was growing along the streams in deep shade. Cyathea dregei is a grassland species usually in the sun. I was shown a frond of both species to compare. The leaves ofCyathea thomsonii have pinnules with only one row of sori on each side of the midrib while those of Cyathea dregei have three or four rows as, I have since discovered, is illustrated in Flora Zambeziaca tab 21 page 73. Having looked up the Red Data List for something else I see that for Cyathea thomsonii it says Site: northern Vumba, Bikita. ‘Not known if it is still there, less than 25 individuals were seen in the late 1970’s. The habitat is probably stable but not protected. I don’t know whose comment that was and if it also applies to the Bikita record. And having also read what Keith said and I did not change, I can see hairs on the undersurface of the leaves of Cyathea thomsonii, with a lens of course, and which the leaves of Cyathea dregei do not have. I have subsequently asked John Burrows who confirmed that he knew of several localities for Cythea thomsonii saying that as it is so similar to Cyathea dregei it may well have been overlooked elsewhere and so determining it’s red data list status could be difficult. I do know that Tom has tried several times to transplant it without any success and if Tom can’t do it no one can. But with the success that nurseries are having growing tree ferns these days this would be the best way of trying to acquire one if any one feels they absolutely must have one. The other doubt that was very strongly expressed was whether Cyathia capensis really exists in Zimbabwe. I have a note that in Zimbabwe it occurs in high altitude moist forests and I am sure that I have seen it at Nyazengu at the base of Nyangani mountain and the altitude at Vumba is not much above that of Harare so it probably does not occur there. Two of the other ferns that I recorded were Blechnum attenuatum and Marattia fraxinea, both of which occur in wet areas in deep shade in forest. Bart pointed out that Marattia is so fussy about habitat that it was growing on one side of the path (the side next to the stream) but not on the other dryer side.

Cephalanthus natalensis. Photo: Bart Wursten. Source: Flora of Zimbabwe

Cephalanthus natalensis. Photo: Bart Wursten. Source: Flora of Zimbabwe

Other trees which I recorded that afternoon were Embelia schimperi, another scandent species, this one climbing by means of hard persistent lateral shoots. The leaves are slightly fleshy and have little elongated translucent glands seen clearly with a lens.Ficus craterostoma, forest fig is always recognisable with the leaf apex very blunt or almost square (truncate), sometimes even concave. Cephalanthus natalensis, strawberry-tree, so called because the fruit are small capsules clustered together somewhat resembling the fruit of a strawberry. We were there at the non-fruiting time so did not see the fruit. This a member of the family Rubiaceae so has leaves in pairs (opposite) but they are distinctive, being small shorter than 5 cm, ovate or egg-shaped and the petiole is slender, kinked, and often tinged with pink, the colour running into the midrib. Another member of the family Rubiaceae was Tarenna pavettoides, which I thought I would always recognise after our trip to the Honde Valley, but I had to be reminded. The leaves are typical of the forest, quite big, dark green with a drip tip, but it does have a label, on each branchlet there is at least one pair of leaves that are distinctly different in size. Another plant with leaves in the pair different sizes that we saw in the understorey in Bunga Forest was Sclerochiton harveyanus, blue-lips, but that has much smaller leaves with the margin irregularly toothed and belonging to the family Acanthaceae..

Going back to Rubiaceae a genus which showed variation between the altitude of the top of the Vumba around the Bunga forest and the altitude at Eden Lodge was PsychotriaPsychotria mahonii we saw that first day. The leaves have up to ten pairs of lateral veins which are very distinct and the undersurface is quite often hairy. Psychotria zombamontana we only saw on days three and four in Bunga and Castleburn forests. These leaves have more than ten pairs of lateral veins and are hairless. I have just realised that there is another difference. The inter-petiolar stipules are up to 1,5 cm long, but those of Psychotria mahonii are divided into two lobes whereas the stipules of Psychotria zombamontana are undivided. One of my problems has always been how to distinguish between Psychotria and Oxyanthus as they both have big leaves with prominent lateral veins. The leaves of Psychotria are decussate, one pair at right angles to the next while those ofOxyanthus are all in the same plane. The other interesting difference is that while Psychotria bears the flowers at the ends of the stems Oxyanthus bears the flowers in clusters in the axils of the leaves with one cluster per node on opposite sides of successive nodes. I know the problems associated with having to wait until the plants flowers, but this position of the flowers is a feature that can probably be visible for quite a long time, first as buds before flowering and then as fruit after flowering.

On the second day, Sunday we went down the Essex Road stopping at various places on the way, one group even got as far as the Burma Valley and bought bananas. At one of the places we stopped, just before we turned off the tar, I found a scandent climber with opposite leaves and the branchlets almost bent backwards to assist with climbing. I rushed back to my book and keyed it out as Tarenna junodii, very exciting. I even found a specimen with some flowers on. When I got home I took one look at the specimen I had collected and realised I had made a horrible mistake. The flowers on the specimen were in the axils of the leaves and Tarenna bears their flowers at the ends of the branchlets. I have gone back and checked my key and I think where I went wrong was I presumed the leaves were small usually 3 to 5 cm long whereas in fact they are many leaves longer than 5 cm. When I followed the key the correct way I came up with Psydrax kraussioides, climbing quar, which it proved to be. Not a very good start, but a good lesson. It might even have been finger-trouble in computer parlance and I just took the wrong route.

A little later Mark emerged from a clump of bush on the side of the road clutching a twig of what he said was Mussaenda arcuata, forest-star, with fruit. I was most impressed that he knew what it was. When in flower I always recognise it. The flowers are yellow with a star of brown hairs in the middle. But the rest of the time it is, or rather now, was a problem. The leaves have a very long petiole, up to 2 cm or even longer and most species in Rubiaceae have a petiole much much shorter than that. So that is a good tip to remember.

At the same stop Mark picked a leaf of what he at first thought might be a Senna but actually looking at the leaf which was pinnate (like a feather with a thing in the middle and bits coming of along the side), it had the leaflets alternate and ending in a single one so we decided it must be a Dalbergia and it has proved to be Dalbergia lactea, large-leaved climbing dalbergia. There are several species of Dalbergia with a tendency to become scandent using other trees for support and climbing by means of coiled branchlets. This one has oblong leaflets with the tip or apex rounded and notched.

Right down at the bottom, more or less on the Mozambique border we were back into bread and butter country. I always think of forest as cake and woodland as bread and butter. This was very special bread and butter. The Brachystegia was Brachystegia utilis, false mufuti, and there were both Uapaca sansibarica, lesser mahobohobo and Uapaca kirkiana, mahobohobo. There were also the familiar Antidesma venosum, tassel-berry, Dalbergia nitidula, purple-wood dalbergia and Pseudolachnostylis maprouneifolia, duikerberry, all that I consider woodland trees but in among them were forest species as well. Two small leaved Rubiaceae; the first Coddia rudis with the leaves broadly obovate (like an upside-down egg) with the base running down the petiole, probably correctly found here in higher rainfall woodland; the second Canthium ngonii, manica spurred canthium, the leaves in pairs at the end of tiny little spurs-branchlets which are also in pairs. The leaves are supposed to smell pungent when crushed. I am afraid that is subsequent information and I did not know to check at the time.

When I wasn’t sure of the identity I put a specimen of leaves in the big plastic bag hanging from my belt. These of course all had to be put into the press but when I got back to the cottage I was too tired to deal with them in the evening and got up early in the morning to do so. Mark, on the other hand, who also had collected specimens into a big plastic bag is a night bird and he dealt with his after supper and sometimes late into the night.

There were some leaves that I collected which I noted as opposite big shiny which I thought must be Rubiaceae as they had a ridge between the opposite petioles and an interpetiolar stipule. It was only when I was having a really good look at them that I spotted that the margin of some of the leaves were slightly serrated around the apex and so was the Rubiaceae look-alike Cassipourea. This one was Cassipourea gummiflua, large-leaved onionwood, which has leaves slightly to distinctly toothed. Cassipourea malosana, onionwood, had presented no problems because that has the margin of the leaves with conspicuously hooked teeth. The wood of some species is supposed to have a strong smell of onion, hence the common name.

It is very frustrating to be able to put something into a family or genus and not be able to give it a name immediately, but on getting home it is quite satisfying to be able to work out the identification and then confirm it in the Herbarium. There were several with distinctly alternate leaves, distichous is the scientific term, i.e, leaves on opposite sides of the stem but arranged alternately, or one could say that they are all in the same plane and so lie flat. One such was obviously a member of the family Annonaceae with leaves slightly blue-green on the undersurface. I think I must have had a mental block, because occurring in forest it couldn’t be anything else but Uvaria lucida, large cluster-pear. Alternate leaves, stems without stipules or stipular scars and the growing tip at an angle to the axis of the stem is characteristic of Annonaceae and also of Ebenaceae in which family is Diospyros, another one I needed to get home before I could identify it. There were two options Diospyros abyssinica, giant jackal-berry or Diospyros ferrea, bristle-fruit jackal-berry. Again I checked in the Herbarium and decided we must have been seeing the giant jackal-berry Diospyros abyssinica, albeit still young because by the time I checked all the leaves on my specimens had all dried and turned black as were all the specimens in the Herbarium, while those of Diospyros ferrea were of a much thicker texture and a sort of dull greyish. That doesn�t really help in the field (or forest). The ideal is to be able to put a name to a tree immediately. Diospyros ferrea has furry growing tips and the young leaves are a coppery green. Diospyros abyssinica has hairless growing tips and the young leaves are reddish. This is one of the tallest trees in Chirinda forest but in the Herbarium there are also specimens from both Vumba and Nyanga so I shall be making a correction to the map in the book.

One of the surprises was the little Diospyros natalensis and it is different from the Diospyros nummularia that we get in our rocky koppies. That has round leaves and the one in the forest had elliptic to ovate leaves. I looked at all the specimens in the herbarium and that was absolutely consistent. So I am quite happy that we have both species in Zimbabwe, even though White found difficulty separating them.

There was one tree with spirally arranged leaves with an entire margin that had us foxed for most of the trip. It was only on the last day as we were going into the Bunga forest when we found one with little white fruit on it that we realised that it was Maesa lanceolata. A tree which we know perfectly well when the leaves have a serrated margin. The book does say occasionally entire in forest specimens.

I have never been very comfortable that I could positively identify the different species of Dracaena. We saw them particularly in the Bunga forest on day four. And those were, of course, Dracaena fragrans, small dracaena, being in the understorey and with leaves on the top half of the of the single stem. The were big broad, strap-like leaves more than 4 cm wide. The other two indigenous species are Dracaena steudneri, northern large-leaved dragon-tree, also with strap-like leaves more than 4 cm wide but those plants tend to be more palm-like sometimes developing a few branches at the top with the leaves in rosettes at the ends of the branches. Dracaena mannii, small-leaved dragon-tree has much narrower leaves, less than 4 cm wide and is usually a much branched small tree, usually occurring singly. Interestingly what is known as dragon’s blood is a resinous exudate used for colouring in varnishes and lacquers and was known to the Ancients who used it to stain horn to resemble tortoise-shell. This exudate has been obtained from some species of Draceana.

Day three was ferns day and Bart and Petra lead us and we looked at many ferns and I duly ticked names and hoped I would remember the names and recognise some of the ferns. But there were too many for a beginner, I enjoyed hearing about them but, I am afraid I soon got lost in trying to learn them. We had a long walk in the Castleburn forest. That can be described as being a wet side of the forest and from a tree point of view was magical. However our walk on the fourth day was in Bunga forest and because we were on the dry side of the forest there were only two ferns, so I was able to come to grips with them, learning the names and recognising them and being able to give them a name every time I saw them. Asplenium sandersonii is a delightful little fern, growing on trees or rocks with once-pinnate fronds, the pinnae or leaflets are obovate with four lobes around the apex. What really intrigued me was the fronds arch and grow from a bud at the end, so it spreads rather like the garden plant that I know as hens-and-chickens. The other one was Pteris catoptera. This is a bit more difficult to describe. The fronds are three-pinnatifid. In other words it looks like a bipinnate leaf but pinnules on the bottom pinnae have divided again and also become pinnate. The frond looks like feathers on a feather but the bottom feathers also have feathers on them. I hope you see what I mean and if you are in Bunga forest that you will be able to see and recognise these ferns too.

And I hope these notes will also help identifying the trees at the Vumba, and that next time having had the opportunity to have a really good look and do a follow up they will help me too. I have also been able to update my key and have thoroughly enjoyed the whole exercise. Thank you to all for their contributions and companionship.

-Meg Coates Palgrave

 

Monday August 11th

In the morning, we met at John’s cottage (our standard meeting point) and set off up the Essex Road heading for the main Vumba Rd which would take us to the Bunga Forest and Ndundu Lodge. On the way we stopped to look at a large roadside fern growing beneath a small tree. The tree turned out to be of interest: Neoboutonia macrocalyx. This has large almost circular leaves and a very reliable spot-character: the underside of the leaves are covered in stellate hairs. I’ve only seen it before deep in the Bunga Forest so it was a little surprising to see it growing on an open roadside.

Our next stop was at a layby on the main road. (It is the one with a picnic site, a very tight bend in the main road and a bridge). From there we walked back along the road looking at both the ferns and the trees. For me it was an absolute pleasure to have Bart and Petra Wursten to identify the ferns and explain some of the features and differences.

For example, two species of “Lycopodium” were growing on the roadside bank. I’ve put the genus in italics because there is a tendency to split the species among different genera. One, Lycopodiella cernua, has small upright branched stems which bear small deflexed cones at the branch tips. The whole impression is somewhat like a small Christmas tree; the other, Lycopodium clavatum, has longer more prostrate stems which occasionally send up a stem with 1-3 cones.

Vernonia wollastonii, a weak semi-climbing composite was everywhere at the edges of the forest.

Also at this point were two very beautiful species of Acanthaceae. One was Isoglossa mossambicensis growing by the road at the edge of the forest. This has pale flowers with prominent orange markings. Also present was the, in many ways even more striking, herb Mimulopsis solmsii. There was less of this and only one bit was in flower so it was actually less impressive on this occasion than the Isoglossa.

Mimulopsis is said to flower gregariously. What is said to happen is that the plants all flower simultaneously, produce copious seed, die back completely. Then, over the next few years, the plants grow again until they again simultaneously flower. This is known as a plietesial flowering cycle. Various species of Acanthaceae do it as also do some species of bamboo.

When we visited Seldomseen the next day, the forest was full of a tall (up to 2-3 metres) Acanthaceae, none of which was flowering. I *believe* (but could be wrong) that this is Mimulopsis and that it is approaching its point of simultaneous flowering. It is one of those things, if one ever lived in the Vumba, could form the basis of some quite simple but fascinating research.

Two, I hope interesting, plants were re-collected in the very wet part of the layby (it is about 6 years since I first saw them), namely a species of Sigesbeckia and a striking blue-flowered Plectranthus. I still have to find names for these, but I hope that they are both species of interest.

On we went, stopping briefly at the Bunga Forest to be shown some ferns, to Ndundu Lodge. There we had lunch. In the afternoon we walked from the Lodge towards the bottom end of the Woodlands Road. The path at first went through some rather dull areas which had been hammered by Cyclone Eline (although even here we kept seeing things of interest). We also were shown some Cyathea manniana (spiny tree ferns) on which were growing the characteristic epiphyte, .

We emerged at the bottom into an open area in which some development had been taking place and from there entered another forest. This turned out to be the most interesting piece of forest we saw during the whole weekend. It is an absolute must to revisit this again whenever we return to the Vumba. Sadly, I have not had time to get names for all the things we collected – I hope to add this at a later date. Certainly here were Chrysophyllum trees, probably gorungosanum, Strophanthus speciosus, Schlerochiton, Rytigynia etc. Some of these have been covered by Meg in her write up.

At this stage, the density of exciting species was such that some of us got a bit behind the rest. We (the tail) emerged from the forest into a quite different habitat of Brachystegia woodland and grassland in a rocky setting and with a magnificent view towards the Himalayas to the south of the Vumba.

It was at this point that Werner stepped into an innocent-looking hole and did some quite serious damage to his leg. Even today, which is 3 months later, the leg is still not entirely better. On the whole we have had few injuries or problems on Tree Society outings and one is inclined to forget that it can happen. The position was that Werner could not walk on the damaged leg, we were some way, maybe 500 metres from the road, and to get Werner out of there would involve getting him through the rocky boulders, up into the forest and along the forest path.

Fortunately, Bart had his cellphone (and we were in an area where there was coverage). He phoned Ndundu Lodge and an assistant came out and brought a vehicle as close as possible. Then, taking it in turns, two of us supported Werner as he hopped on the one good leg back to the car.

Then back to Ndundu Lodge for some drinks before a very welcome fire.

 

Tuesday, August 12th

Werner decided to remain at the cottage today. The morning was spent in the Bunga Forest. We parked our cars at Colin Saunders’ house and walked from there. One of the most interesting things was how open the area had become; once again this is the effect of Cyclone Eline.

In the afternoon, we visited Seldomseen. This is a familiar stamping ground for the Tree Society and I don’t think we saw anything new. Once again, the forest was much more open than I remember it – probably because big trees were taken out by the Cyclone. It was also full of the Mimulopsis , as we have already discussed.

One genuinely interesting thing was a specimen of Brillantaisia subulugurica behaving as a tree. We took a picture of it with Meg standing by it. This is a new species for the 4th edition of Coates Palgrave!

After the walk we spent some time admiring the views from the lowest cottage (Crimson Wing) and then toiled up the steep drive where we were kindly given tea by the manager and his wife.

All in all it was a fascinating few days and I would like if possible to revisit the Vumba early next year.

My thanks go to John Bennett without whom the trip would never have happened. Very special thanks must also go to Bart and Petra who assisted in so many ways with local advice, including lunch at the lodge on two days, support to rescue Werner and of course information about ferns, orchids, trees and the Vumba in general.

To Werner, I would like to say I am sorry the trip turned out badly! But also to thank him for talking about and for naming the orchids we found. I’d also like to thank Meg Coates Palgrave who was our official leader on one day and co-leader on several others and in particular for providing so much information over the trip.

Ann Bianchi is very kindly donating 20 trees to the Tree Society to help raise some much needed cash.� If you would like a particular tree let any of the Committee members know and we will try to arrange it for you.

Thank You Ann.

 

 

MARK HYDE  CHAIRMAN

 

 

 

 

 

 

 

COMMITTEE MEMBERS’ CONTACT TEL. NUMBERS

Harare

Mark Hyde Home 745263
Cell 091233751

Rose Greig Home 490250

Lyn Mullin Home 747169

Eva Keller Home 339368
Office 610029/33

Maureen Silva-Jones Home 740479
Cell 011719601

Bulawayo

Jonathan Timberlake Home 286529

The Tree Society’s e-mail address is
trees@mango.zw

 

Casearia battiscombei. Photo: Bart Wursten. Source: Flora of Zimbabwe