I have had no response from my earlier message (see below), but I may have something new to add. A friend from Morocco has been kind enough to scan a few branches of the herb in questions to me. Here are some scans which I hope will make it easier to identify the variety.
I thank you in advance for your assistance.

----- Original Message -----
I have puchased several artemisia varieties from your company in search of= a species that grows in north africa (morocco) which I have so far failed to identify.
My first guess was that it would be the Artemisia afra species for which I bought some seeds but so far what has grown (they are still small), looks more like A. absynthium than what I am looking for.
Of all the varieties I have tried, the closest by far is Artemisia 'Powis Castle' which is a near identical looking plant, with a similar odour/fragrance. Can you tell me if you know of any other variety that very closely resembles Powis Castle in every aspect (size of leaves, colour, odour)?
As an example, 'Silver Bush' also resembles the plant but has no odour and the leaves are a little bit more delicate than the variety I am looking for. Tree wormwood has much larger leaves also.
The mystery variety is used in Morocco as an alternative to mint and thyme to flavor green tea and it is occasionaly imported by some stores here on Montreal. For some reason they only get it (import it) in the winter, and only cut branches – no roots.
The plant is known in Morroco as "shiba" (pronounced "sheebah").

Sorry about the delay in responding to your message. The fault is mine because your original message was forwarded to me for comment by our horticulturist, Inge Poot, but unfortunately it went astray in my hands.
The trouble with the genus, Artemisia, is that it has many species, and within the species there are many varieties and forms. The plant "shiba" may be a form or variety of one of the species that we already grow. Or, it could just as easily be a different species altogether. Without flowers, especially, it is near impossible to positively identify plants; the best we can do is suggest possible candidates.
If it is indeed belongs to one of the species we carry, my guess is that it is a form of tree wormwood (A. arborescens). It could be a form of it, or perhaps a hybrid between it and another species. 'Powis Castle', the variety you thought was closest to resembling "shiba" is thought to be a hybrid between A. arborescens and A. absinthium, so it is entirely possible that your plant could be a similar hybrid.
In the 1980s I was friends with a janitor at the University of Toronto who was from North Africa. During my many late night conducting research in the lab I often had the opportunity to chat with my friend about North African herbs. He was ecstatic about our tree wormwood; he insisted that it was exactly the same as what he remembered from home. Despite poor growing conditions in his home, he managed to grow dozens of healthy plants and was very proud of them.
If you wish, we would be willing to try to grow plants from branches that are sold in Montreal in winter. If you send us a few fresh branches we will try our best to grow it and will compare it to our existing varieties.

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