Violets and others: Rosa tomentosa Harsh Downy-rose

Rosa tomentosa Harsh Downy-rose.

A few post flowering photos taken on 2nd July 2026 in Cambridgeshire.

Rosa tomentosa, outstanding feature is the very long pedicels with lots of glands.

The pedicel glands immediately rule out those tricky Dog-roses, so this is definitely an interesting plant. The length of the pedicels being up to 3cm is quite extreme. We are looking at a Sweet Briar or a Downy rose and long pedicels are really only found in either R. micrantha or R. tomentosa.

These two share many common features but R. micrantha would have 'few to many' obvious glands on the underside of the leaf. amongst some hairs. often limited to veins.

R. tomentosa would normally have high density of hairs on the leaf underside, although this is a variable feature and some plants have a much lower density. Stalked glandular hairs on the underside of the leaf can often be absent here in Cambridgeshire or on occasion quite a lot can be present. If large glandular tips are present, (0.1mm diameter), consider looking for acicles just in case you have found the rare hybrid with R. rubiginosa.

R. tomentosa Underside of leaf showing quite dense hairs and the odd gland on the surface.

Many R. tomentosa plants in Cambridgeshire have a very high density of hairs, being fully tomentose and no glands visible on the leaf surface. This plant has a few glands on the surface and more on the secondary veins and lots on the main vein. It is the leaf surface glands that are most useful for identification in that they are small downy rose type at about 0.05mm diameter. The sweet briar equivalent glands would be 0.1-0.12mm in diameter.

At higher magnification they have stalks and a tiny glandular head not much thicker than the stalk.

The odour of leaf glands can be smelled, but is not as strong as that of R. rubiginosa or R. micrantha.

So we have glandular pedicels, long pedicels, dense under leaf hairs and even some glands ( not always present) so next up is to look at the leaf margin.

The new BSBI Rose handbooks suggest the leaf margin of R. tomentosa should be biserrate or multi serrate. As usual, the major tips have hydathodes supplied by a vein, and the sides of the tips have secondary minor sub-tips with stalked glands.

We do not have the major tip, then secondary smaller tip sequence here ( biserrate), just major tips with minor tips caused by the stalked glands. To me this is multi serrate. Tony O'Mahony in Ireland expects R. tomentosa to have multi serrate margins and biserrate or serrate edges may indicate a cross to R. corymbifera, at least in County Cork.

The distinction between hydathodes and glandular tips can occasionally become blurred as I have seen glandular tips which are at the end of a vein and also hydathodes which are not the normal conical shape and have a round ball, however this is unusual. See previous blog on Rose leaf margins.

This is all good for R. tomentosa but R. micrantha also has a similar leaf edge. Both are multi-serrate. Many other features are shared, like a flat to slightly convex disc and a narrow orifice.

R. tomentosa Slightly convex disc with a narrow orifice at 0.8mm max.(1/5th diameter. of disc.)

R. tomentosa Orifice small and you can just see some hairs in the styles although broken off to show the size of the orifice.

R. tomentosa Close up of orifice with cylindrical hole and some remaining styles and hairs.

According to the new handbook the styles can be glabrous or slightly hairy whereas in R. micrantha the styles should be glabrous (no hairs). A minor point to suggest the plant is R. tomentosa.

A wider orifice opens up other species like R. sherardii and mollis and hybrids. It is always worth cutting a hip through the orifice to check shape and diameter as it is one of the more important features in confirming an identification.

To complete the set of photos, next up is a close up of the leaf stipule.

R. tomentosa Leaf stipule and petiole ( leaf stalk).

Not only the margin but also the stipule surface is covered with large stalked red glands. The margin is showing round stalked glands which are staying on, unlike the stipule glands on the Dog roses.

R. tomentosa Sepal, hairy on top surface and glandular beneath with pinnate side projections. often sepals can have leaf like extensions.

These sepals are slightly reflexed when you might expect the sepals to be spreading-erect, however it is now known that the sepals of R. tomentosa are very variable in the angle they take up and can be very variable on the same plant. They also can fall off quite quickly.

R. tomentosa

Final shot of a prickle showing quite a strong straight shape whereas R. micrantha would have a more curved prickle.

Conclusion.

I was happy that this plant fitted the requirements of being a R. tomentosa. The narrow orifice is useful in discounting the other Downy roses ( R. sherardii and R. mollis, see separate blog) and was interested to see how many features were shared with R. micrantha.

With all roses you have to look at all features before deciding what name to put on it and even then recheck to see if everything fits or suggests a hybrid. The main problem with hybrids is weighting the importance of features to decide what possible parents have been involved. Not easy.

Peter Leonard

Cottenham, Cambridgeshire, UK

July 2026

Reference. Wild Roses of Great Britain and Ireland by Roger Maskew & Gareth Knass, BSBI Handbook no 26, 2025.

Additional photos. R. tomentosa usually has hairs on upper surface of leaf which this plant did but the hairs were quite hard to see and was variable in density. R. micrantha usually does not have upper leaf hairs.