Small-leaved Cotoneaster - how to distinguish?

I've been interested in Cotoneaster with leaves smaller than the fruits. I recently posted these photos as Cotoneaster horizontalis. But just now I saw a photo of Cotoneaster dammeri 'Tom Thumb' that looks exactly the same to me. I was going by the little prickle on the leaf tip. Maybe these leaves are too small for C. dammeri? I see that there is also C. apiculatus, which is what I'd like to call leaves with a little leaf tip prickle, and they also look the same to me in photos. It doesn't help that this page Oregon State U. page at Cotoneaster apiculatus 'Tom Thumb' | Landscape Plants | Oregon State University shows all three species that I'm mentioning here, and a few others, but calls the 'Tom Thumb' cultivar C. apiculatus.

and this that I thought was the same, but maybe not.


I came across the dammeri name when I was looking for the name of this, which I think is Cotoneaster microphyllus. I based that on the tiny leaves and no prickles at the leaf tips.


In September, I photographed this, called it C. apiculata in my notes.


Is there some visual cue to help here? Is the branch arrangement any different? One tidier than the other? C. dammeri should have the largest leaves of the ones I mentioned, at 2-3cm. But C. apiculata dimensions overlap those of C. horizontalis according to the Oregon State site.

 

Do you have any idea what was the ubiquitous Cotoneaster that it seemed every Vancouver house had fanned up against its foundation in the the 1950s (probably earlier too)? At one time, I thought it was C. horizontalis but maybe not. My grandmother had one and I remember, as a child, thinking it was very stiff and unattractive but I have a greater appreciation for it now. ( Still wouldn't plant it though. :-) )

 

I'm not answering Margot's question.
But I may as well pack in the Cotoneaster shrubs. Here's one I saw today, with relatively huge leaves - ha, maybe 2 cm long. Cotoneaster simonsii?

 

I don't know. According to Cotoneaster simonsii | Landscape Plants | Oregon State University, where I came up with that name, that's supposed to be "Deciduous to semi-evergreen", fruits ovoid. Here is the plant in the previous posting in winter.

 

Cotoneasters: A Comprehensive Guide to Shrubs for Flowers, Fruit, and Foliage: Fryer, Jeanette, Hylmö, Bertil: 9780881929270: Amazon.com: Books

Flora of the Pacific Northwest, 2nd Edition (pnwherbaria.org)

 

I am only slightly less confused about the first three photos, two locations, in this thread, now that I can see that they are deciduous. Though I mentioned C. dammeri, which is supposed to be evergreen in mild winter areas, the OSU website for C. horizontalis, Cotoneaster horizontalis | Landscape Plants | Oregon State Universit, says it's deciduous, and mentions "layered (like a spray of water), low spreading; fish-bone branching habit". I don't really get the spray of water description, but I had definitely been planning to describe the branching pattern as fish-like even before reading that. Well, I have read this page before, but I did not remember anything about that. So based on the fish skeletons, I think those first two locations are C. horizontalis. That would seem to be the case for the last one in the first posting as well, but I wasn't able to find that today.
Here are winter photos for the plant in the first two photos:


And the third photo, second location:


I haven't posted this one before - in Alexandra Park along Beach Avenue. There are at least three Cotoneaster species along the street on this block. These branches look pretty fishy, so I have named them C. horizontalis.


I still think that the third location, which I called Cotoneaster microphyllus, really is that. It is appropriately evergreen.

 

Here are two more of the Cotoneaster microphyllus, same planting as the previous photo. These are definitely the smallest leaves, barely larger than the fruits. These are the dullest of the fruits here. The first photo is a crop from the first posting, showing that although the fruits appear sessile, they are on very short stems.


I found at least one more species here along Beach Avenue in Alexandra Park, maybe two. I think this is Cotoneaster dammeri, based on the way the fruits are hanging away from the branches on relatively long curved stems.

This group is farther west on the block.


This group I can't figure out. Leave size is very variable, but tops out a little over 2cm. The fruits, which are sort of bell-shaped, are on very short stems, but some seem to be in an inflorescence of two or three.

 

Subject area is too complex to be wading in firing off identifications without using keys and descriptions prepared by experts in the subject. Such as those present in the two references I mentioned previously.

Complex to the extent that eastern (as in Chinese) authors do not agree with western (European and North American) interpretations.

 

Well, I'd like to call them something, and recognize when the shrub here is the same as the one over there, or is it different. Surely we don't refrain from using any names because it's complicated.
All of them are complicated?
The level of complexity you're talking about is beyond my comprehension (as the review of the second book assured me).

 

There are complexes of generally similar species told apart from one another by specific details. With in addition various ones long grown in western gardens having been found in later times by specialists such as the one surviving co author of the Timber Press book to have been called the wrong names the whole time. Any references not having incorporated her findings in particular will not be in step with the actual situation.

 

Translation?

 

Anything I use as a reference is likely to be wrong - I can list all the details I want and say they match the description on some website, but I won't know if that's a website using the wrong names that have been in use all along.

 

So use the references I recommended.

 

OK, OK, I've placed a hold at the public library on the Flora of the Pac NW; I should have it in a few days.
The other one I would have to buy, from Amazon, $50CAD (includes delivery), would arrive some time in February. Other options either don't ship here or were way expensive.
I hope you like the first one just as well.

 

There's also this:

Cotoneaster in Flora of North America @ efloras.org

 

What I like about this book is that the key starts with stuff I can deal with - it divides them into four groups based on leaves: hairy beneath, deciduous or evergreen, or not hairy beneath, deciduous or evergreen. Also, I really like the glossary and the table of abbreviations. And the drawings. And I didn't feel I was getting lost in the key, except that I don't understand the numbering of the names on the right margin.
What's not so good is that it doesn't include C. apiculatus or C. microphyllus. Based on just what is covered, I seem to have fired off some pretty apt names, but it doesn't mention anything about all this complexity, and the missing species have a lot to do with that.
What I have learned that I want to remember are:
C. divaricatus has oblong fruits
C. atropurpureus and C. hjelmqvistii have roundish leaves, the latter particularly so, and fruits on that should be orange-red.

First off, I have learned that "Cotoneaster integrifolius was treated as C. microphyllus Wallich ex Lindley var. thymifolius (Baker) Koehne by L. Lingdi and A. R. Brach (2003)." That definitely saves me some hair pulling. Pomes dull or slightly shiny, glaucous.

The other two mentioned here that I would want to keep in mind are C. conspicuus, Leaf blades 6–12(–20) x 2–6(–8) mm, adaxial surfaces grayish green, dull to slightly shiny; styles and pyrenes 2(or 3), pomes shiny;
and C. ×suecicus, Leaf blades 10–27 x 4–12 mm, adaxial surfaces dark green, shiny, flat between lateral veins; styles and pyrenes 2–4(or 5) (always some with more than 2), pomes shiny. I'm getting the idea this might be common. Cotoneaster xsuecicus in Flora of North America @ efloras.org mentions inflorescences, with 1 or 2 flowers, up to six. Navel open. I wonder if that's distinctive. I also wonder if it's my unknown in Posting #7 (last group).

Here is a new location, and this has an open navel. I think this is the same as what I called C. dammeri above, which is one of the parents of C. ×suecicus.

 

@wcutler, I am very impressed by your focus and determination to identify these plants accurately.

 

I'm just adding one to the club. Several years ago, I posted this as Cotoneaster rotundifolius at UBCBG. I didn't see the label, but I think I figured it out from the plot, and I noted that it had particularly large fruits.

 

I found a planting at the Park Board Office that looks the same, with red on the inside of the sepals. I see these shown at UK Wildflowers - Rosaceae - Cotoneaster Microphyllus, Small-leaved Cotoneaster (uksouthwest.net).
According to my Cotoneasters book (Fryer & Hylmö, Portland, Timber Press, 2009, p.128-129), C. microphyllus should have leaves that are "elliptic, obovate, broadly-elliptic or broadly-ovovate". In the index under that name, under C. microphyllus f. linearifolius, it sent me off to C. thymifolius, which has leaves that are "linear or narrowly obovate" (p. 132). But it mentions that that species was previously thought to be a form of C. integrifolius, which has leaves that are "oblanceolate, oblong, rarely lanceolate" (p. 128-129) and which is the only mention I can find of sepals having at the apex a red margin. Well, I haven't read the whole book yet.


Edited September 9, 2021
I am adding photos from yesterday of the Park Board plant that I am still calling C. integrifolius. I have read the whole section under Series Microphylli and this species is the only one that mentions red sepals. I consider this a seriously notable feature, one that would be mentioned if it were the case.

I must not be understanding what all counts as a fertile shoot - it's supposed to have 2-3 leaves and one flower; this looks like a lot more leaves than that. The last photo looks like 3 leaves. It reminds me of why I knew I would not be a scientist, when in school we had to dissect a frog and draw what we saw. I did exactly that and failed the assignment; everyone else copied the drawing in the book and got and A.

 

I have edited the posting just above to add autumn photos for the plant at the Park Board office that I think looks just like the Alexandra Park plant here that I'm still calling C. microphyllus, because I haven't paid attention to the flowers. Same deal with the number of leaves on the fertile shoot. Nothing is supposed to have this many leaves belonging to one fruit, but really, I think I'm in the right section of the book. I'm just not understanding this.

 

I'll say this much - the fish-scale appearance of C. horizontalis is way cool. It's hard for me to imagine you'd have found it that unattractive. Here are more photos of what has to be that species along Beach Avenue in Alexandra Park, west of the steps. This planting appears above in posting #6, the three photos before the last one.



To the east of the steps is another planting that in detail looks similar to me. The habit just looks a little less tidy.

 

I apologize. It is beautiful to my eyes now. I have to say though none that I saw as a 5- or 6-year-old were nearly as gorgeous.

Is there a book on Cotoneasters I wonder? If not, maybe you should think about writing one, drawing on all your knowledge and fabulous photographs.

 

That's a "no" - C. simonsii fruits are supposed to be glabrous (hairless).

I'm expecting this to be in the Series Franchetioides, maybe C. wardii because of all the hairs. Except that the fruit is ripe now, and C. wardii fruits are due to ripen in November. And these leaves are a little shorter and fatter. I'll have to remember to check the flowers next year.
Here are more photos.

 

Yes, I've been using the one Ron B suggested above:
Cotoneasters: A Comprehensive Guide to Shrubs for Flowers, Fruit, and Foliage: Fryer, Jeanette, Hylmö, Bertil: 9780881929270: Amazon.com: Books
I cited it in posting 19, and unless I enter a link, it's the only reference I'm using now. 344 pages, including an excellent very necessary glossary and 200 very clear photos. The book covers 460 taxa. What I can't tell is what is likely to be found around here vs. what I can rule out as not occurring here. At least for the moment, I'm only interested in the little-leafed ones. That's not exactly a botanical distinction.

 

Spacing relative to the other two shrubs suggests it was purchased and planted, although it is still possible it came up spontaneously. Including in another spot, after which it was moved to where it is now. Both the 2018 Hitchcock & Cronquist and the eFloras North American treatment address species known to have been going wild on this continent. An additional option is to contact North American authority on the genus Peter Zika directly, he should be able to name most material from spontaneous occurrences. And Jacobson also once got a determination from Fryer. But in either case I of course am not suggesting that the world now shower them with hundreds of requests for free identifications.