TREE LIFE 529
SEPTEMBER 2024
FUTURE EVENTS
PLANNED EVENTS:- SEPTEMBER
Since inclement weather or other issues may vary our plans, WhatsApp Tony Alegria on 0772 438 697 to join our WhatsApp group for last minute updates.
Saturday 7th September 2024:- visit to the National Botanic Gardens. Meet at 8.30 in the main car park and join us for an interesting morning looking at trees that catch our interest.
Saturday 28th September 2024:- visit to Athol Evans. We begin botanising at 2:30 pm. The entrance is off the Chiremba Road and we meet in the carpark on the righthand side just inside the gate. Please watch your WhatsApp for further details.
REPORTS FROM PREVIOUS OUTINGS
VISIT TO ST. MICHAEL’S PRESENTATION PRIMARY SCHOOL: SUNDAY 21ST JULY 2024
By Mark Hyde, photos by Mark Hyde and Bart Wursten (From Zimbabwe Flora website)
We were a small group who assembled near the School buildings: Catherine Shadwell (headmistress), Tony Alegria (leader), Jim Dryburgh, Dawn Siemers, Edwicks Chidziva and me.
The area covered by St Michael’s is surprisingly large; Tony and I did a recce in June and we were surprised how much space there is at the back. However, today, our chosen route took us back along the school drive and around the edge of one of the fields returning to the main school buildings, a total distance of about 1 kilometre. This distance took us just over 2 hours, a reminder of how slowly the Tree Society moves and also the number of interesting woody plants one comes across in gardens.
It is probably true to say that most of the trees we examined had been planted but they were a mixture of indigenous and exotic and in particular, there were some very nice large msasas which have been preserved in the school grounds.
Ixora sp. ?finlaysoniana
The first shrub we examined was a planted species of Ixora. The genus belongs to the coffee family, Rubiaceae, and the flowers are grouped in heads, lax in some species, tight and flat-topped in others.
There is a native species, which is found in localised patches of the riverine forest in the Eastern Districts. There are also some species of Ixora planted in gardens where the long tubes and relatively short lobes of the individual flowers make it a popular garden plant. The name of the cultivated species we saw on this day is not clear but could be Ixora finlaysoniana, an Asian species. This picture comes from 29th June 2024, the day we did the recce, and even then the plant was going over, but it does show the tightly clustered white flowers.
A genus often planted in gardens is Jasminum. Jasmines have opposite leaves and usefully come with varied leaf characters – some have simple leaves (J. multiflorum which is white-flowered is the commonest cultivated one in Harare); some are 3-foliolate (J. mesnyi, yellow-flowered is the most common one) and others have pinnate leaves (the powerfully-scented pinkish-white J. polyanthum is the most often seen in this group). The leaf structure assists with identification as the plants can be quickly placed in a specific group.
Chrysojasminum humile
A small group of species of Jasminum with alternate leaves has been moved out of the genus into a new genus called Chrysojasminum. These are all yellow-flowered (chryso- is Greek for yellow). At St Michael’s we came across one of these namely Chrysojasminum humile. The English name has not changed and remains Italian jasmine.
On next to a couple of planted albizias. Albizia schimperiana, the Forest long-pod albizia, is indigenous and in Zimbabwe occurs in our Eastern Highlands’ forests. It is occasionally planted in Harare gardens and in some cases forms exceptionally large trees; a well-known example being the one planted adjacent to the National Herbarium in the Botanic Gardens. There is also a gigantic specimen at Flame Lily Retirement Home in Marlborough.
The leaflets are less rectangular than Albizia adianthifolia and gummifera and usually have two prominent veins arising from the base of the leaflet, It also lacks the coloured female parts found in gummifera.
Nearby was Albizia lebbeck, an exotic species, native from the Indian Subcontinent to Myanmar. Perhaps because I have only learned to identify this in the last few years, I have not found this to be common at all. The name lebbeck arises from an Arabian vernacular name for this species.
At this time of year, there was not a lot in flower. Callistemon viminalis (the Weeping bottlebrush) was flowering but this seems to flower more or less throughout the year. Bauhinia variegata was opening up, somewhat earlier than usual, perhaps because of the very warm month.
Most of the species discussed so far have been exotic, but there were several good indigenous species. Specimens of Calodendrum capense, Schotia brachypetala, Peltophorum africanum, and Grewia flavescens with its characteristic angled stems, were seen. There were also two species of Acacia, namely galpinii and karroo, Dombeya rotundifolia, Euphorbia ingens, Parinari curatellifolia and Thespesia (formerly Azanza) garckeana.
Redwing – Pterolobium stellatum
Also found near one of the walls of the property was the Redwing, Pterolobium stellatum. This scrambling shrub with 2-pinnate leaves is exceedingly well-armed with prickles and it would seem to be potentially an excellent barrier plant deterring trespass. However, despite this, it is rarely cultivated, in Harare at least.
There are still some unidentified plants – some species of Melaleuca are one example – so a return visit some time when more things are flowering would be of great interest.
Finally, many thanks to Catherine Shadwell for permission to visit the School.
NATIONAL BOTANIC GARDEN OUTING:- SATURDAY 3rd AUGUST 2024
By Tony Alegria, photos from Zimbabwe Flora web site – Mike Bingham
On a cool, sunny, cloudless Saturday morning the ladies: Soo Fawcett, Barbara Maasdorp and Dido de Swardt along with the guys: Jan van Bel, Jim Dryburgh, Busi Malunga, Stuart Wood and I enjoyed a morning’s tree outing. Barbara wanted to see typical highveld trees, so I decided to see these and the brachystegias.
Brachystegia allenii (sessile leaflets)
First up were two small Brachystegia allenii. Escarpment brachystegia which have sessile leaflets I don’t think these two trees have ever been in flower. Nearby was a Terminalia prunioides with almost dry fruit so the purple colouring was not that obvious. Also nearby was a leafless bush which turned out to be a Dalbergia martinii. Zambezi dalbergia with not so sticky pods as they were now dry.
On the way to see a Commiphora marlothii which never fails to amaze me with its paper-thin peeling bark and bright green trunk, we looked briefly at: Sterculia quinqueloba with small pods but no leaves, Balanites maughamii with its Y-thorns and Vepris zambesiaca with its winged petiole and soft velvety leaflets.
We compared the almost leafless Brachystegia spiciformis. Musasa with a Julbernardia globiflora. Munondo and noted the difference in fruit. Munondo has its smallish brown fruit above the canopy whilst the msasa, has its bigger greener pods within the leaves. Not to be seen now was the difference in leaves and inflorescence. There is a page in our website comparing the two trees. Once the three main differences are known, these two look-alike trees can be identified whilst driving past them! The msasa is considered to be a friendly tree as the two largest leaves wave (flutter) in the slightest breeze.
The distinctive bark of
Brachystegia tamarindoides
The Mountain acacia name is an enigma! How can you call a tree which is found on the summits of rocky hills and koppies (Not Mountains!) and is a brachystegia (Not an Acacia) by that name?
There are a few (old name) Brachystegia tamarindoides in the garden with very few leaves but with rather distinctive-looking bark.
The next tree was an almost leafless Brachystegia boehmii. Prince-of-wales feathers or Mufuti but we did see one with leaves later on next to the last brachystegia we saw, that is the Brachystegia microphylla. Small-leaved brachystegia from the hills or mountains in the eastern districts. This tree was now in new leaf and they sure were tiny!
Some of the other trees we looked at that were not mentioned above: Combretum molle, Dalbergia melanoxylon, Dalbergia nitidula, Cleistochlamys kirkii, early-flowering Albizia anthelmintica with green pollen, Erythrina abyssinica and a newly renamed Dovyalis afra. Kei apple.
VISIT TO EWANRIGG BOTANICAL GARDEN:- SUNDAY 18TH AUGUST 2024
By John Lawerence with additional comments from Tony Alegria
Dido, Barbara, Dawn, Mark, Jan, Jim, John and Tony together with Jonothan and Tinashe from National Parks staff spent an enjoyable and informative morning at Ewanrigg under the leadership of Tony.
It was a beautiful day for botanising; sunny, with a chilly breeze to begin with, warming as the morning went on but never too hot. We met in the picnic area near the entrance and made our slow way around interesting trees there before walking up the kopje to the aloe and cactus garden.
Having looked at the trees there we made our way down the other side to the road and back to the picnic site. There were very few other visitors to the garden that morning; maybe avoidance of any potential trouble associated with the SADC Summit that weekend had something to do with their absence.
View of Ewanrigg Botanical Gardens
from Zimbabwe Flora website
There is an abundance of tree species in the garden, both indigenous and exotic, which made identification challenging for the inexperienced, or in my case the forgetful, but exciting for the experts.
The Tree Society has put a lot of effort into identifying the trees present over the years and has produced a list, but there still remains a handful of “mystrees” about which even Mark is unsure. The fact that in August significant numbers were leafless, flowerless and fruitless did not help.
What did impress me was the vast amount of collective knowledge on trees that is available within the Society: identification characteristics; botanical names with all their continually changing variations; distribution; habits of growth, flowering and fruiting; edibility or otherwise of fruits and nuts; suitability or otherwise for gardens. Everyone had something to contribute.
What amused me was how sensitive botanical names are to politics, and how reluctant members are to accept names that seem to defy the rules of scientific nomenclature laid down centuries ago; is it Rhus or Searsia, is it Acacia or one of the other names that the Australians have forced upon Africa, which few of us can remember. The latest example is the change of specific names from caffra to afra. The unspeakable original word in the common names of Erythrina and Strychnos species was replaced years ago, but now the word that refers to the origin of the type specimen has been changed because it might give offence. Does that mean that the Eastern Cape should have been known as Affraria?
We said farewell to the National Parks staff, with encouragements for them to help to replace the original identification numbers on the trees put there by the Society, few of which remain. They were given a modified chisel to loosen labels that were now being engulfed by the tree growing. Where labels have been destroyed they were told to contact Tony with a list of replacement numbers. It is hoped to start looking at all the trees in the garden!
We enjoyed a relaxed picnic lunch together at two tables in the shade and were back in town by early afternoon.
OTHER NEWS AND SHORT NOTES
BOTANISTS VOTE TO REMOVE RACIAL SLUR FROM HUNDREDS OF PLANT SPECIES NAMES
Edited from the Smithsonian Magazine, July 24 2024, by Margherita Bassi
After six days of heated discussions, 351 of 556 researchers at the International Botanical Congress in Madrid conducted a secret ballot vote on whether to eliminate a “c” in more than 200 scientific names of plants.
The nomenclature change will modify the names of species with derivatives of the word caffra, an “apartheid-era racial slur” used against Black people in Southern Africa, “afr”.
For example, Erythrina caffra will be called Erythrina afra. This decision marks the first time taxonomists have voted in favour of changing offensive scientific names.
The nomenclature proposal was initiated by Gideon Smith and Estrela Figueiredo, two plant taxonomists at Nelson Mandela University in South Africa who have spent years campaigning for the international taxonomy system to allow the changes of offensive plant and animal names.
In addition, a new special committee will now be able to flag problematic species names for review, however, it is not allowed to consider names given before 2026.
“This is an absolutely monumental first step in addressing an issue that has become a real problem in botany and also in other biological sciences,” botanist Sandy Knapp of the Natural History Museum in London, who managed the week-long nomenclature session said “It is a very important start.”
Note: This article has simply been included for information so that members understand the logic behind name changes, whether or not they agree with it.
Stereospermum showing paler
under-bark
STEREOSPERMUM KUNTHIANUM
It can be confused with mauve species of Handroanthus (the new name for Tabebuia) which are in the same family and have similar flowers. Usually, both species have no leaves at flowering time and the best way of separating them is from the bark; Stereospermum has very distinctive, grey, smooth bark which flakes to reveal paler under-bark.
Stereospermum kunthianum
This tree is harvested from the wild for local use as a food and a source of wood. The roots and leaves are used in traditional medicine but it is often grown as an ornamental shrub. This picture of the flowers is from a tree found next to Chiwanza Rock on the Katiyo Tea Estates.
My thanks to Tanya Scott for bringing this photo by Scott Higgins and the location of the plant to my attention.
PHOTOS FROM JIM DRYBURGH
Every month Jim sends me some stunning photos of plants that have caught his eye. Here are a few from recent outings in the Miombo woodland, kindly named by Mark Hyde.
1. Turraea nilotica
2. Fernandoa abbreviata
3. Carissa edulis
4. Globimetula mweroensis
5. Calliandra haematocephala (red form)
6. Calliandra haematocephala (cream form)
7. Senna sp.
TALKING TREES?
Are forests socialist or is the ‘wood-wide web’ a fantasy?
There are something like eight billion humans, hot-breathed individuals, downloading apps, piling into buses and shoving their plasticky waste into bins, and yet humans are not Earth’s chief occupants. Trees are. There are three trillion of them, with a collective biomass thousands of times that of humanity. But although they outnumber us by nearly 400 to one – they’re easy to miss.
Impala in Miombo woodland
Show someone a photograph of some miombo woodland with impala in the distance and ask what they see. “Impala,” they’ll triumphantly exclaim, as if the trees occupying most of the frame weren’t there. “Plant blindness” is the name for this.
Admittedly, trees do not in general draw our attention. Apart from plopping the occasional fruit upon the head of a pondering physicist, they achieve little that is of narrative interest.
Or, at least, they were until recently. The German forester Peter Wohlleben’s surprise bestseller, The Hidden Life of Trees (published in English in 2016), has inaugurated a new tree discourse, which sees them not as inert objects but as having thoughts and desires, and they converse via the fungi that connect their roots “like fibre-optic internet cables”.
The idea comes from an unlikely source. In 1997, a young Canadian forest ecologist named Suzanne Simard together with five co-authors published a paper in Nature magazine – “The net transfer of carbon between ectomycorrhizal tree species in the field” – inspiring Nature’s cover story and the indelible pun: this was the “wood-wide web”. This paper claimed that trees don’t just supply sugars to each other; they can also transmit distress signals, and they shunt resources to neighbours in need. The proposition was that the forest is a socialist community.
In 2016, Simard gave her much-watched Ted Talk, “How Trees Talk to Each Other” (over 5m views). In this, she highlights the fact that forests are not just the trees you see but all the organisms above and below the ground. The mycorrhizal network connects different individuals in a forest, and not just individuals of the same species. The one fact her research has shown is that “mother” trees send excess radioactive carbon dioxide to seedlings, with a preference for seedings of her own species! Trees communicate via the essentials for life; carbon dioxide, nitrogen, water, phosphorus and hormones!
A mycorrhysal network
It turns out trees are not just competitors, they are co-operators. They communicate.
But before enfolding their rough barks in our soft arms, we would do well to pause a beat. Whereas researchers must usually toil in respectable obscurity for decades before their ideas attract notice, the intelligent-plant notion is moving at top speed. Public demand, as much as peer review, is driving the train, with popular books reporting excitedly on studies that scientists are still debating – sometimes outracing the science entirely. It’s worth asking what makes us so eager to ascribe human qualities to the arboreal world. Might we be missing something important when we gaze into the wooden mirror and see only ourselves?
Is more botanical revisionism to come? Just as AI (artificial intelligence) champions note that neural networks, despite lacking actual neurons, can nevertheless perform strikingly brain-like functions, some botanists conjure notions of VI (vegetal intelligence).
My thanks to Rob Kelly for bringing to my attention the original article by Daniel Immerwahr. I hope this short summary provides some food for thought.
Linda Hyde
TREE SOCIETY COMMITTEE AND CONTACTS
Chairman Tony Alegria tonyalegria47@gmail.com 0772 438 697
Vice Chairman Mark Hyde mahyde@gmail.com 0772 233 751
Honorary Treasurer Bill Clarke wrc@mweb.co.zw 0772 252 720
Secretary Teig Howson teig.howson@gmail.com 0772 256 364
Venue Organiser Ann Sinclair jimandannsincs@zol.co.zw 0772 433 125
Committee Member Jan van Bel jan_vanbel@yahoo.com 0772 440 287
Committee Member Ryan Truscott ryan.kerr.truscott@gmail.com 0772 354 144
Committee Member Sibusiso Malunga busimalunga@yahoo.com 0775 889 898
Tree Life Editor Linda Hyde Lmharwin@pentact.co.zw 0772 232 075
Tree Society Website https://www.treesociety.org.zw/
Tree Society Facebook https://www.facebook.com/groups/ztreesociety/
Flora of Zimbabwe: https://www.zimbabweflora.co.zw/
Flora of Tropical Africa: https://plants.jstor.org/collection/FLOTA
