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

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!

Posted on October 13, 2023 06:29 PM by galpinmd