galpinmd's Journal

This post represents the second chapter in my 'Hunt for Searsia longispina'. The first chapter detailing the reasons I set out on my quest can be found in the link below:

The hunt for Searsia longispina: Chapter 1....Clueless!

At the end of the first chapter, I posted a link to a Searsia species I thought might be Searsia longispina (hereafter referred to as Longispina), and after a lot of discussion and collaboration and referring back to Moffatts work on the Searsia genus, we (thanks @annsymons) came to the conclusion that the species in the observation was indeed Longispina. The observation and related discussion can be found in the link below.

Searsia longispina observation with discussion

(anyone reading this who wants a digital copy of Moffatts work on the Searsia genus, PM me your email address and I'll send it through - it is 10Mb in size)

As a visual learner, it gave me the visual reference I needed for an idea as to what Longispina would look like, but I still needed to see other specimens in the field in order to be able to confidently identify the species. Of course, once I had 'locked' onto Longispina so to speak, I saw Longispina in just about every bush I looked at! That being said, I did have the opportunity to travel through areas where it is known to occur and slowly but surely I started to be able to pick out what I thought was Longispina. On one of these trips, I happened to notice a lone specimen close to the Nanaga Farm Stall - and for anyone who knows this Farm Stall, it is an obligatory stop - their Lamb and Mint pies are worth the detour! On my return trip, I stopped at the bush and took a few photo's which can be found in the link below.

The Nanaga Longispina bush

This specimen is only the second 'live' specimen that I can say I have had a good look at, and with all the previous discussions and collaborations with others, I am certain that the above specimen is Longispina.
Of course, the question that I would ask after a confident statement like that would be "Well, what exactly makes it Longispina?" I'm glad you asked!
This next section will list the features that pertain to Longispina, according to the work on the Searsia genus by R.O. Moffatt. Links are provided to observations that best depict (in my opinion) the feature listed.

GROWTH HABIT (architecture)
. Recognised by the habit of forming dense, rounded, multi-stemmed shrubs with pale spinous branches
Photo 1 in the link for habit
Longispina habit
Photo 2 for young branches with long spurs
Long spurs on young branches 1
Photo 1 for young branches with long spurs
Long spurs on young branches 2
Photo 3 for shorter spurs on older branches
Shorter spurs on older branches

BRANCHES
. Finely striate (slender grooves or channels); pale grey-brown to dull yellowish in colour with squarrose (bend slightly downward at the tip), spinous (pointed, sharp) spurs
Photo 5 in the link as an example of a striate branch
Striated branch
Photo 1 in the link for squarrose spurs
Squarrose spurs

LEAVES
. Trifoliate
. Petiolate; petiole semiterete (semi-circular in cross section), canaliculate (grooved) and sometimes margined
Photos 1 & 3 in the link
Petiole 1
Photo 7 in the link
Petiole 2
. Somewhat fasciculate (a bundle or cluster of leaves crowded together) to crowded on spurs
Photo 3 for crowded, fasciculate growth on spurs
Fasciculate leaves 1
Photo 2 for crowded fasciculate growth on spurs
Fasciculate leaves 2
. Glabrous (smooth or glossy i.e. not hairy)
. Often laccate (as if varnished), occasionally glaucescent (blue-grey in colour)
. Lamina (leaf blade) oblanceolate (upperside down spear shape), spatulate (spoon shape) to narrowly obovate (upside down oval i.e. widest in the top half tapering to the base), often convex (curved slightly upwards - like a wide 'V')
. Apex: emarginate (indented at the tip), retuse (blunt or rounded apex with a small notch), mucronulate (tipped with a small point/spine), entire (no teeth or serrations), rounded to subacute (tapered but not sharply pointed)
See photos of leaves in the links
Longispina leaves 1
Longispina leaves 2
. Venation: Kladodromous (veins divide or branch toward the margins), secondary veins curve upwards just short of the margin; midrib slightly prominent above and below
Photo 9 in the link showing venation
Leaf venation 1
Photo 1 in the link showing venation
Leaf venation 2

DRUPE (fruit)
. Shiny, pale green ripening to chestnut-brown
Photos 4 & 6 in the link
Longispina drupes

DISTRIBUTION (where it occurs)
The description below of Longispina's range is quoted directly from Moffatts work:
"Ranges from near Queenstown in the north-eastern Cape, through the eastern, southern and western Cape interior to near Alexander Bay in Namaqualand. It is especially plentiful in the lower Great Karroo becoming scarcer westwards until it is rare in the north-western Cape. There is a single record from Oribi Gorge near Port Shepstone in Natal"

The distribution map of Longispina observations on iNaturalist can be found in the link below
Longispina distribution map

WHAT TO PHOTOGRAPH
"I think this might be Searsia longispina - now what do I do?"

You might end up asking yourself this question while standing in front of tree and want to know what you should photograph in order to be able to get someone to be able to ID it for you.
Remember, it can be really challenging to ID a tree from photographs. In the case of Longispina , and other Searsia spp too, there are a couple of photos which would prove useful in being able to identify it.
Take a look at the sequence of photos in the link below taken of a Longispina bush.
Sequence of photos of Longispina

The observations in the link will give you an idea of what features to photograph - the descriptions of which follow below:
. A wide angle shot of the whole shrub showing the habit (the shape and architecture of the plant)
. A closer shot showing the branching
. A closer shot of a branch showing the arrangement of the leaves/fruit on the branch and spines
. A close up of the upper and underside of some leaves - lay some out on your hand, it doesn't have to be a single leaf
. A close up, backlit shot of a single leaf or leaflet showing the venation
These photos will be a great help to anyone trying to ID Longispina, with 'try' being the operative word - Searsia are a real challenge to identify!

I think that about wraps up my hunt for what has been an elusive species for me. I hope that others will find it a little easier to pick out Longispina now, and hopefully more records will come in giving us an even better idea of what it looks like and where it can be found.

Remember, keep plugging away at trying to ID these plants for yourself, and don't give up too soon!

In a previous Journal post 'The hunt for Searsia longispina', reference was made to a journal paper by R.O. Moffatt in which he deals with the confusion between Searsia longispina and Searsia pterota, two species which I had mixed up for a long time. The paper by Moffatt can be found in the link below:

https://www.sciencedirect.com/science/article/pii/S0254629916306597

My hunt for S. longispina is ongoing at present, and my journal post detailing that hunt can be found in the link below:

https://www.inaturalist.org/journal/galpinmd/85712-the-hunt-for-searsia-longispina

For years I had referred to Searsia pterota (hereafter referred to as Pterota) as Searisa longispina but once I was made aware that the two species were not at all related, it became much easier to identify Pterota. It is a species that is quite common in the areas that I explore (the south eastern cape - the area between Gqheberha(Port Elizabeth), Buffalo City(East London) and Makhanda(Grahamstown) and I have found it to be one of the easier Searsia species to identify in the field. That being said, identifying specimens in photographs can be challenging as photos don't often show all the features that would set Pterota apart from other species.
Just a note: Some of the plants pictured in the links that follow are plants photographed beyond the borders of the area I explore.

In the next part I'll go into some detail with regards to descriptive terms, relying on R.O. Moffatts work on the Searsia genus. This is useful as a reference for identifying Pterota but if you're just wanting the basics, or the most useful features that I tend to rely on, you can skip to the summary section and always refer back to the 'technical' section for the features described.

Just a note: Where links are provided, the photo or photo's that best depict the feature being referred to will be numbered e.g. 'Photos 2, 3 & 4 in the link'. I have found this process to be a little cumbersome as I often forget what the number of the photograph was that I needed to look at, and then end up going backwards and forwards between the Journal post and the observations in the link! My advice is to go slowly and open one link at a time - and have a cup of coffee and a rusk on standby next to you!

THE LEAVES

• Leaves are trifoliate (the leaf is made up of three leaflets, a terminal leaflet-in the middle, and two lateral leaflets-one on each side of the terminal leaflet)
  Photos 7, 8 & 9 in the link
  Trifoliate leaf

• Fasciculate (a bundle or cluster of leaves crowded together)
  Photos 2 & 8 in the link
  Fasciculate leaves 1
  Photo 3 in the link
  Fasciculate leaves 2

• Petiolate (leaflets are connected to the stem by a petiole)

• Petiole winged (from the Greek word 'pteron' meaning 'winged' - this is how Pterota got it's name)
  Photo 1 in the link
  Winged petiole 1
  Photo 6 in the link
  Winged petiole 2
  Photos 3 & 5 in the link
  Winged petiole 3
  ** Some plants can have markedly winged petioles, but the plants in the links above give a good idea of what one will usually find in my opinion

• Rigidly coriaceous (rigidly leathery - the species has quite a tough leaf)
• Slightly discolorous (darkish green on the upper surface, slightly lighter on the underside - no big difference in colour btw the upper and underside)
• Glabrous (smooth i.e. no hairs)
• Lamina elliptic to obovate (Lamina = leaf blade; elliptic = an ellipse, widest in the middle and tapering toward each end; Obovate = teardrop shaped, with widest part near the tip, tapering toward the base)
• Apex rounded (tip of the leaf isn't pointy)
• Base cuneate (base is wedge shaped where it meets the petiole)
• Margin entire and revolute (Entire = smooth edge i.e. no serrations, teeth etc; Revolute = margin folds downward along its edge)

• Venation kladodromous (a very useful feature - basically means that the veins divide or branch toward the margins; 'klados' from ancient Greek meaning 'branch' and 'dromos' an adjective from Greek meaning 'a running' Think of the Hippodrome of ancient Rome - a horse racing track)
  Photo 7 in the link
  Kladodromous leaf venation 1
  Photo 7 in the link
  Kladodromous leaf venation 2

• Veins dull yellow in colour (a useful feature)
  Photo 1 in the link gives a good overall impression of venation colour
  Leaf vein colour

• Secondary veins often reversed (in other words some veins often reverse direction, away from the margin, back towards the midrib)
  Photo 7 in the link
  Reversed leaf venation

• Secondary veins 2-3 per cm (worthwhile keeping in the back of your mind when it comes to comparing between Searsia species)

• Leaflet size in mm (Terminal leaflets average 25 x 10; lateral leaflets average 19 x 9 - length/width - there is quite a big variation in size, even on the same tree!)
  Photo 6 in the link
  Leaf sizes

THE DRUPE (fruit)

The drupe is not always seen in the field especially if a person is only visiting an area for a short time, as one has to be around when the plant is in fruit. Drupe features can be critical in identifying Searsia species, especially when a **key is used. Moffatt used two words to describe Searsia drupe shape, the first word used describes the shape as viewed on its widest face and the other, its thickness, or the shape perpendicular to the widest face.
**A key is a tool used to identify an organism and is made up of a sequence of choices between two or more statements

So here goes for drupe features

• Elliptic (widest in the middle and tapering toward each end- remember this description refers to its widest face)
• Ellipsoid (according to Wikipedia this is a 'three dimensional shape that is elliptical in all sections through the long axis'. I would imagine that if you had to cut the drupe in half while viewing it's thickness, the flat surface that you would see would be elliptic in shape)
• Slightly asymmetric (so not quite an evenly shaped ellipse)
• Glabrous (Smooth)
• Shiny
• Fleshy
• Colour: dark reddish brown drying black

• Pungent and unpalatable (other Searsia drupes can taste quite pleasant - a bit tart, but refreshing. In the case of Pterota however, I'd suggest you draw straws to see who gets to try!)
  See photos of fruit in links
  Pterota drupe 1
  Pterota drupe 2
  Pterota drupe 3

GROWTH HABIT (architecture)

The descriptions given in Moffatts work are as follows:

• A much branched, armed shrub (it has spines) , branching squarrose (bending outward or downward at the tip), short shoots ending in sharp spines.

• Young growth russet coloured
  See photo in link
  Russet coloured growth

• Bark: grey, granular and often lichen covered

DISTRIBUTION
The following description of Pterota's distribution is a direct quote from Moffatts work:
"Ranges along the coast and adjacent interior from East London to the De Hoop Nature Reserve near Bredasdorp in the southern Cape with a disjunct population 250 km further west in the Postberg Nature Reserve near Saldanha Bay"

The distribution of Pterota observations on iNaturalist can be found in the link below
Distribution map

SUMMARY

The two most useful characteristics that I use to identify Pterota are its leaf characteristics (shape, venation and petiole features) and habit (the architecture of the plant).
This species tends mostly to grow in amongst other shrubs, as opposed to out in the open by itself, and its presence is most often given away by spiny branches (sometimes quite long) protruding from a clump of shrubs usually at, or close to, the edge of the clump. This is the one species of Searsia in my area which will poke a hole in you and draw blood if a branch whips back and hits you!
Photo 1 in the link for growth habit
Growth habit 1
Photo 2 in the link for growth habit
Growth habit 2
Photos 2 & 4 for spines
Spines

The ability to identify species based on what is termed 'GISS' (General Impression of Shape and Size) takes time and, if you don't know this species well, will require one to get 'up close and personal' as opposed to being able to identify it from a distance. The most useful features for an 'up close and personal' investigation of the shrub are listed below (in order of importance to me)

• Leaf venation - untidy venation, yellowish veins that branch (kladodromous) - they get squiggly toward the margins
  Photo 7
  Leaf venation

• Long, winged petiole (watch out for this one - if it's there, it's easy to identify this species, if not, go back to venation
  Photos 2, 6, 8 & 9 in the link (notice in photo 1 that the petioles are not very obvious, but the venation gives the species away)
  Winged petiole 1
  Photos 3, 5 & 6 (notice in photo 6 the variation in leaf petiole length)
  Winged petiole 2

• Fasciculate leaf growth (a bundle or cluster of leaves crowded together)
  Photos 2 & 8 in the link
  Fasciculate leaves 1
  Photo 3 in the link
  Fasciculate leaves 2

• Leaf shape (elliptic = widest in the middle and tapering toward each end, to obovate = shaped like an upside-down tear drop)
  See photo's of leaves in the two links for an idea of leaf shape in this species
  Leaf shape 1
  Photo 6, second leaf from the left, the terminal leaflet is a good example of an 'elliptic' shape
  Leaf shape 2

• Sharp spines
  Photos 2 & 4
  Spines

• Main stem with lichen covered bark and some nasty spines
  Photo 2 in the link
  Main stem and spines

The post above is not meant to be taken as an authoritative post on Pterota. It includes details from the work of R.O. Moffatt, a man I consider as the authority on Searsia, and input from people with far more experience and knowledge than I have, but it still includes my own limited, local knowledge and understanding of the species. I'm sure I'll be amending this post as time goes by but for now that should be enough to get anyone started on identifying Pterota. Enjoy the journey - and don't give up too soon!

This is very much an amateur naturalists' journey detailing my quest to confidently identify Searsia longispina. The quest to identify Searsia species is challenging - so, challenge accepted!

I'd grown up referring to what is now Searsia pterota (Rhus as the genus was known then) as Searsia longispina. In my interactions with other, more knowledgeable folk on iNaturalist, it became apparent these were two quite different species.
According to a Journal article by R.O. Moffatt titled 'Rhus longispina and Rhus pterota, two hitherto confused South African shrubs' published in 1994, the confusion between the two above mentioned species still persists.
The article by Moffatt can be found in the link below (Thanks @sandraf!)

https://www.sciencedirect.com/science/article/pii/S0254629916306597

In the fifth paragraph of Moffatts introduction, two phrases caught my eye:
'...these two species are not closely related...' (referring to longispina and pterota)
and
'...R. longispina is related to R. pallens...."

This then begs the question "What then does S. longispina actually look like?"

I'm glad you asked!

I'm someone who needs to see a plant or at least a picture/photo of a plant or its parts in order to make sense of the botanical descriptions that relate to that plant - words/language are not my strong point! (Writing this article is like pulling teeth for me!)
That being said I decided to make my way up to the Selmar Schonland Herbarium in Makhanda (Grahamstown) to see if I could find the specimens that Moffatt had looked at in the Herbariums collection. I managed to photograph some of the specimens and these can be found in the link below:

https://www.inaturalist.org/observations/187370283

It is difficult enough trying to identify trees when one is standing in front of a live specimen, but to identify a part of a tree that is dead and dry is a whole other level.
The question then asked while looking at the specimens was "What features was Moffatt looking at in each specimen that he could confidently identify each as being S. longispina?"
I'm not a botanist by training, but there were a few common features that became apparent as I paged through each specimen.

1. The shape of the leaflets, in particular the terminal leaflet (photo's 1,2 and 4 have good pictures of leaflets)
2. The venation of the terminal leaflets.
3. Long, narrow (thin) petioles.
4. Spurs (short outgrowths from the branches that remind one of thorns - Photo 1 shows them nicely)
5. Leaves fascicled (clusters of leaves) on the stems and spurs.

According to Moffatts description of S. longispinas growth habit/form, it would be best depicted - in my opinion - by the form of the Searsia species in the observation below (Thanks @craigpeter)

https://www.inaturalist.org/observations/155707266

The problem with this form is that there are a few Searsia species that grow like this, if given the room to to do so, and this growth form is not readily discernible if the plant is growing in amongst other bushes and shrubs.

So far in this quest I now have an idea of what to look for and the knowledge, thanks to Moffatts work, that this species does occur in my stomping grounds - BUT - finding a species that I've never seen before, based on herbarium specimens, and in an area as diverse as my part of the Eastern Cape is, is an enormous challenge. In saying that though, I MIGHT just have gotten lucky, take a look at this specimen in the link below:

https://www.inaturalist.org/observations/184983822

This is the only specimen I know of in my stomping grounds that looks like this and I'm VERY tempted to call it S. longispina, it certainly fits all the features that I could see in the herbarium specimens, but then again, am I seeing what I want to see? - you tell me......

For the sequel to this riveting tale and the answer to the question in the paragraph above - click on the link below for Chapter 2
Chapter 2....Target acquired!