A rather mysterious mahonia
I don’t like posting about plants that I am not 100% sure about but I offer this in the hope that someone may be able to confirm whether or not this is the plant I bought it as! It is supposed to be Mahonia trifolia and, as such, a rather rare species from high altitude in Mexico. I can find very little about the plant and there is also a M. trifoliata which is very different. Mahonia trifolia is suppose to be closely related to Mahonia moranensis but that looks very different to my plant with softer leaves much more like a hot-house-raised M. aquifolium. My plant is a bit of a ‘hard nut’ with very spiky leaves and dense clusters of golden yellow flowers from orange buds. Since I got the plant, the leaves have taken on a purplish tone in the cold weather. It has a rather stiff habit and I am not sure how elegant it is going to be in maturity but I will cut it some slack for now – it is too prickly to argue with. I got it because I was intrigued by it. I still am and also rather pleased.
The Biking Gardener 
Wow, I have no idea what that is. I only started to learn about all the many other species in the last two years or so. Prior to that, I had worked with only about three. Mahonia aquifolium used to be the common one.
Mahonia aquifolium used to be the most commonly grown here but M x media cultivars, especially ‘Charity’ are the most commonly encountered here now.
That is a nice one for the right applications, but it is a completely different personality. To me, it looks like Mahonia lomariifolia, but better behaved. I think it would suit an atrium in an Eichler House quite nicely. I like the formerly common Mahonia aquifolium because it looks rather woodsy, natural and unrefined. As some cultivars of Mahonia look more refined, . . . it sort of defeats the purpose; unless of course, one wants to landscape an Eichler House. Yours looks like a Mahonia for the chaparral. It is a genus that should be more popular than it is. The problem I see is that so-called ‘gardeners’ do not know how to maintain them. I work with some that had been shorn for a long time. In some spots, I just cut them to the ground and let them start over. There are a few where I cut out the oldest bits until new canes replace the rest. It is why I like it in my own garden, but not at work.
I had to look up what an Eichler House was – I want one 🙂 I agree that M. aquifolium is more woody – though that may be because I saw so much of it – or a similar but related sp. when visiting California and Oregon and seeing it in woods and forests. I also agree about the habitat of my species – some are tough, thorny, arid country plants. I think this one is a bit inbetween but I am being kind to it right now and not stressing it too much. The flowers are opening in very tight clusters and have a pleasant scent. AND I agree that mahonias are one of those plants that is maligned because of the way it is treated. Some plants are so forgiving that they end up being ugly and it is not their fault
Eichler Houses were very distinctive. There were some rather luxurious ones, and also some less expensive tract houses. Some consider the tract houses to be ‘cheap’. Others really appreciate their simplicity. Their floor plans were comparable to those of old (although not too old at the time) Californian Spanish houses, with some windows facing into small inner courtyards, and not so many prominent windows facing out from the front of the home. Some of the front windows were up under the eaves, and only for light. Larger floor to ceiling windows faced more into courtyard, side yards or backyards. That is why smaller and sculptural plant material suited them so well. They are very stylish, and, although not a style I would want to live with, they are fun to work with and select appropriate plant material for. There is actually an list of plant material that is ‘approved’ for small Eichler houses.
Fortunately, the few Mahonias that I have worked with recover remarkably well from major abuse. Mahonia lomariifolia does not spread, or produce pups far from the original trunk, so gets pruned back in phases rather than all at once. Mahonia aquifolium is really tough. I think if were to try another, it would likely be a straight species, rather than an ‘improved’ cultivar.
I have seen in the habitat and cultivate that species. Quite frequent on the Iztaccihuatl between 2200-2400 m on vertical basalt rocks with Juniperus monticola f. compacta and Echeveria secunda. The cliffs are surrounded by puna like vegetation. More recently Zamudio et al. Taxon 66: 1388 (2017) published B. alpina with 3 leaflets. My plant from Izta. has 3 leaflets on terminals and 5 further down. I believe your can use Berberis, or Mahonia trifolia for your taxon.
Mahonia trifolia Cham. & Schltdl., Linnaea 5(2): 211 (1830).
Berberis trifolia Schult.f., Syst. Veg., ed. 15 bis [Roemer & Schultes] 7(2): 1616 (1830).
syn. Mahonia schiedeana Fedde, Bot. Jahrb. Syst. 31(1-2): 90 (1901).
syn. Berberis schiedeana Schltdl., Bot. Zeitung (Berlin) 12: 654 (1854).
syn. Mahonia schiedeana Fedde, Bot. Jahrb. Syst. 31(1-2): 90 (1901).
Thank you so much for your help. I am pleased to say that the mahonia is growing well, albeit slowly, though this is not a shock now I know where it comes from. Thank you for your help.