Expedition no. 7: Tree Society visit to Aberfoyle Lodge: 17 Sep 2010-20 Sep 2010

A visit by the Tree Society to explore the low-medium altitude forests in the Honde Valley.


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Description

Friday 17th – Monday 20th September, 2010

Introduction (by Mark Hyde)

This was the first extended Tree Society outing since August 2006, when we went to John Galt village near Juliasdale. In the ensuing 4 years as inflation went hyper, fuel supplies became erratic and our members’ incomes were squeezed, our longer outings became impossible to arrange.

However, since dollarisation in February 2009, the resulting price stability and fuel becoming available, we began to contemplate longer trips.

With great efficiency and attention to detail, Bill Clarke, our newly-appointed treasurer planned the trip. It was one of the most organised Tree Society outings ever.

Sixteen members took over almost the entire Lodge on a self-catering basis: Peter Buttress, Bill Clarke and Fiona Lawrance, Meg Coates Palgrave, JP & Vicki Félu, Mark & Linda Hyde, John Meikle, David & Lynne Mills, Simon & Joy Pitt, Mimi Rowe and Bob & Sue Tanner. Soo Fawcett joined us on a daily basis.

This article was written by two authors, J-P Félu, who wrote a combined account of Friday and Saturday, and myself. There is some overlap.

It has taken a very long time for this account to appear; however Meg Coates Palgrave and I were able to identify (nearly) all the material we collected, thereby enabling a fairly complete report of what we saw to be presented.

Friday, 17th and Saturday 18th, September (by J-P Félu)

Aberfoyle is a tea estate in the Honde valley. It is some 374km from Harare (Lincoln Green). The lodge is situated at an altitude of 838 metres above sea-level, 18°17,651' South and 32°58,120' East of Greenwich.

Friday was devoted to driving there. Maybe the most spectacular part of the route is the road from Rusape to Juliasdale that climbs to 1918m altitude and gave us the splendid spectacle of Brachystegia spiciformis in all their shades of reds and brown. At that altitude the growth of the Msasa is stunted giving them a Japanese sort of geometry. Near Susurumba there is a spectacular patch of Acacia abyssinica (Nyanga flat-top) well worth looking at.

The rest of the road to Aberfoyle was not particularly spectacular except for the incredible profusion of Lantana camara, it is a pity that no-one has ever found any commercial value for it.

Winding through the tea estates we finally arrived at the lodge, charmingly situated at the end of a neatly set golf course.

After freshening up we took our first botanical walk on the edge of the golf course. No, we did not make the 19th hole, in fact, as the sun set we had reached the second hole! However, by Saturday lunch time we made it to the bottom of the golf course.

The biodiversity of plants is staggering and, as the species are very different from both Mashonaland and Matabeleland, our poor brains were struggling with unfamiliar and new names.

Our first confusion arose with the two species of Macaranga (capensis and mellifera). Given the altitude at which we were, all the Macaranga should have been Macaranga capensis with conspicuously peltate leaves (that is with the stalk attached some distance from the margin of the leaf). Unfortunately some trees were hardly peltate at all, had no spines on the branches and no gland-tipped leaves, to make matter worse their overall shape appeared to be more elongated than those of the Macaranga capensis, the feeling was that, maybe, some were Macaranga mellifera but one must be cautious, as far as I know not all homo are sapiens.

Much easier was the Anthocleista grandiflora, a tropical looking tree with very large spathulate leaves and a favorite of Harare gardeners.

A new Bridelia to me was Bridelia micrantha, a rather fast-growing species that has been used in the furniture industry and could certainly be used to line city streets given the bright coloring of its falling leaves.

A fascinating sight was the Harungana madagascariensis, the "orange­milk tree", also known as "praying hands" because the new leaves stick together for some time before separating, giving the impression of two hands joined in prayer.

An interesting tree, even though exotic, was a Burmese teak tree (Tectona grandis); it belongs to the family Lamiaceae (mint family) and is totally different from our teak which is a Caesalpinioideae (Fabaceae).

Near the bottom of the golf course a Ficus craterostoma, with its very characteristic truncate leaves, and a Maranthes goetzeniana (Chrysobalanaceae, the family of our common Parinari curatelifolia) made an impressive display.

Early on Saturday a small tree attracted our attention as it looked like some kind of Combretum, unexpected in this environment. It proved to be a Combretaceae and more precisely a Pteleopsis myrtifolia (Two winged stink­bushwillow).

Friday 17th September (by Mark Hyde)

Mostly a travelling day. Mimi Rowe, Meg Coates Palgrave, Linda and I journeyed for 6 hours, with almost no stops, in our ageing Land Cruiser to arrive at Aberfoyle at about 2.30 in the afternoon.

The weather was warm and very hazy, and we saw frequent fires. At Aberfoyle it was very rarely possible to get good pictures of the scenery because of this haze.

By the road there was a lot of Vernonia myriantha (the Eared vernonia). As we entered the more eastern highlands type vegetation, V. myriantha remained prominent often accompanied by Helichrysum kraussii and Arthrixia rosmarinifolia.

We met up with JP and Vicki Félu photographing an Acacia abyssinica, and they followed us down into the Honde Valley. The Honde Valley itself has the feel of a lush Communal Land and so we decided not to stop and pressed on to the Lodge, where we were met by Bill and presented with a glass of sherry.

In the afternoon we did our first walk, along by the river by the golf course. There was lots of interest and some quite difficult things and not unexpectedly we spent about 2 hours walking about 300 metres! – much to the amusement of many of those present.

J-P has already mentioned most of the species seen and there is not much to add. I was surprised at how difficult it was to identify the two Maracanga species: M. mellifera and M. capensis. The problems were not solved by looking at the specimens in the Herbarium either. However, eventually Meg and I concluded that all the material we saw and/or collected on this trip was M. capensis.

Another interesting pair of species is Albizia adianthifolia and A. gummifera. I had brought with me a photocopy of the relevant pages from Flora Zambesiaca (“FZ”) and I spent some time looking at these.

As a general rule, the two species occur at different altitudes with an altitude of perhaps 1100m being the dividing line – gummifera at higher altitudes, adianthifolia at lower; therefore one would expect to see adianthifolia at Aberfoyle, where we were botanising at around 850m.

Fortunately, on Sunday morning, Soo Fawcett handed us a branch of adianthifolia in spectacular flower. This enabled us to look at the characters which define this species:

(a) the underside of the leaflets is densely pubescent all over (pubescent only on the midrib and margins in gummifera);

(b) the leaflet lacks a “heel” (which is present in gummifera - “auriculate on the proximal side” to use the technical language of FZ).

Further less useful characters are:

(i) the bark (usually smooth in gummifera and rough in adianthifolia). Although exceptions to this rule have been reported, this still seems a useful character.

(ii) the indumentum of the twigs and pods (pale brown hairs or hairless in gummifera, usually dark brown, persistent hairs in adianthifolia);

(iii) the shape of the stipules (ovate in gummifera, lanceolate in adianthifolia);

(iv) the colour of the long-exerted staminal tubes (a strong red in gummifera, usually greenish in adianthifolia).

Meg Coates Palgrave and I subsequently looked at the specimens in the National Herbarium. The 'heel' and hairiness characters (as given in FZ) seem to work pretty well. Sometimes it was difficult to see the hairiness in some specimens of adianthifolia and sometimes the shape of the heel was a bit ambiguous but in general we could split the two and agreed with the way they had been curated in SRGH.

We also both agreed that one specimen of mine collected on 17 September by the Aberfoyle golf course was clearly gummifera; although we only had the leaves to work on – no flowers, fruits or trunk to support this.

The conclusion seems to be that altitude is not absolutely reliable and care needs to be taken to check the leaflets with a lens when identifying these species.

To make us feel at home, power went off at 6 pm! Later they put on the ‘hydro’ to the main buildings so we had lights for dinner. This was a formal sit-down affair at which Bill and I made short introductory speeches about the forthcoming weekend.

Saturday, 18th September

(by Mark Hyde)

We started in the same place as the previous day, namely by the golf course and during the long morning we walked along the fairways looking at the trees and other plants on either side.

One extraordinary species was Drymaria cordata, a small herb. This occurs in great quantity in open areas and at the forest edges. It has sticky inflorescences which adhered strongly to our legs and shoes. It was quite difficult to remove, especially if, like me, you have hairy legs. This is obviously a very successful dispersal mechanism.

By a stream was a small yellow-flowered composite, which was unknown to me. To my surprise it was producing milky latex. Later we saw it in a very different habitat growing out of the base of a wall at the Lodge. At the time I thought it was a species called Youngia japonica, however there are no definite records for this species. I recall some years ago Bob Drummond mentioning that it had been recorded in Zimbabwe. Comparison with the very limited material at SRGH and information on the web suggests that Youngia is similar but is a rather bigger plant than the one we found at Aberfoyle. At the moment therefore there is still a question as to what this plant is.

Soo Fawcett showed us a fine Xylopia tree, growing at the edge of the tea and a debate ensued as to whether it was X. aethiopica (many red-fingers) or X. parviflora (few red-fingers). Unfortunately no fruits (the red fingers referred to in the vernacular names) were present and nor were flowers, so we were unable to identify it at the time. However, later work in the Herbarium showed that it was X. aethiopica; the distinction being that in aethiopica the leaf lamina runs some way down the petiole whereas in parviflora it does not.

Further along the golf course, Soo showed us a fine Ficus craterostoma, (Forest fig) with its leaves with truncate or notched tips, growing on a Maranthes goetzeniana.

I find Maranthes is a puzzling species, maybe because we hardly ever see it or because it belongs on its own in a small family (Chrysobalanaceae) and is rather difficult to place. With its alternate simple leaves and the glands on the lamina, it somewhat resembles Euphorbiaceae. Fruits were seen high up on one of the trees.

Growing by the golf course were some young naturalised Spathodea campanulata (African flame tree). Not far away was a large planted tree which may well have been the parent. This is a very interesting record. Although we have a record of it as naturalised in Mozambique, also from a tea estate and at a similar altitude (800m) at the SDH CHA Sarl Tea Estates at Gurué, I have never myself seen it naturalised. This is somewhat surprising as it is very commonly planted around Harare and has many opportunities to escape.

Another naturalised species was a Coffea. The shape of the leaves was closest to ‘robusta’ coffee, Coffea canephora, rather than the ‘arabica’ types which we have seen naturalised elsewhere.

Two climbing species of Strychnos were found close to one another. One, S. angolensis, has small leaves and solitary tendrils whereas S. lucens, which was growing conveniently nearby, had larger more glossy leaves and tendrils in pairs.

An unusual composite seen was Vernonia holstii. This is one of the woody vernonias. It is a shrub and may attain the height of 4m (per FZ) but doesn’t seem to ever reach true tree size. It has white flowers in large heads and occurs along forest margins.

In the late afternoon we drove a short way from the Lodge and walked along at the edge of some woodland. We puzzled for ages in the field over a white-flowered Dalbergia. Was it D. boehmii or D. nitidula? Later, we puzzled over the specimen again in the Herbarium, eventually concluding that it was D. nitidula.

Also at this stop were the characteristic large pinnate leaves of Millettia stuhlmannii (the Panga panga).

Back at the lodge I spent the first part of the evening changing specimen drying papers. We then gathered for the evening meal, for which Bill and Fiona had arranged hats (old, new, formal and comical) for everyone and a convivial evening followed.

to be continued ...


Copyright: Mark Hyde, Bart Wursten, Petra Ballings and Meg Coates Palgrave, 2002-17

Hyde, M.A., Wursten, B.T., Ballings, P. & Coates Palgrave, M. (2017). Flora of Zimbabwe: Expedition no. 7: Tree Society visit to Aberfoyle Lodge.
http://www.zimbabweflora.co.zw/speciesdata/outing-display.php?outing_id=7, retrieved 27 April 2017

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