Wednesday, 8 September 2021

Rosa Mollis Soft Downy rose

Rosa Mollis  Soft Downy Rose,  a search up North....

Having started last year to photograph wild Roses found in Cambridgeshire, a chance to see some more northern species in 2021 seemed a good idea. The Downy Roses are a difficult group and with photos taken of R. tomentosa and R. sherardii in Cambridgeshire, an obvious target was Rosa mollis, the Soft Downy Rose.  And I wanted to photograph the most 'pure' example , if any rose is ever 100% 'pure'.

Since my daughter is now living in Newcastle, research of the BSBI maps showed potential targets near Newcastle and also around Allendale Town, home of the other mollis, Crepis mollis the Northern Hawks-beard. I then moved on to Teesdale and Ingleborough.

First stop was the Gosforth Nature Reserve just to the North of Newcastle, an area of wetland and woodland. Having paid the £5 entry fee,  I headed down the track from the entrance hut and within 20meters found the target, next to a Dog Rose. Five pounds well spent!

R. mollis, 3rd July 2021, Boundary Ride, Gosforth Nature Reserve.

 The first thing to notice was the dull leaves, a feature shared with the other two Downy roses. More subtle, was the lack of arching branches, giving it a lower height despite some thick near vertical stems. Flowering was nearly over but a couple of flowers that were still showing, were a bright and quite deep pink. Time to get out the BSBI handbook on roses and check that its features actually all conformed.

According to the handbook, the first key feature of R. mollis is the straight patent prickles. Prickles can be variable on roses and don't always quite obey the rules, so it is worth checking more than one stem to get an overall impression.

Mature prickle on an older stem, is patent (sticking out at 90 degrees) and quite thin.
It has a large oval base and is not unlike the lowest example shown in the illustration in the handbook.

R. mollis. Patent, straight and thin prickle. 3rd July 2021

R. mollis, New growth prickle.

R. mollis, stem just below pedicle with narrow fine prickles.

These prickles all look good for Rosa mollis as they are a critical feature and later, on my journey, I found R. mollis which were not quite so pure and started to have more curved and thicker prickles.

The main feature is that they are very thin despite having a wide base and that they stick out straight at either 90 degrees or slightly upwards. A comparison shot of Sherard's Downy Rose follows which shows more tapering and curving. 

R. sherardii. New growth prickle. 9th July 2021.

Lealets.

R. mollis. Upper leaf which is quite dull and leaflets just about spaced apart.

R. mollis. Upper surface is hairy. Quite dense simple white hairs all over surface.


R. mollis. Underside of leaflet. Tomentose 
This photo does not quite show the tiny glandular hairs which are almost hidden by the thick white simple hairs. These glands are hard to see due to their small size.
Blown up section of previous photo which just about shows the glandular hairs on the veins and leaflet surface. These are much smaller than the glandular hairs on the leaflet margin.

 These small sized glandular hairs are a key separator from the Sweet Briar roses like R. rubiginosa which have glands twice the size at 0.1 to 0.12mm dia.

Next up is the leaflet margin which should be 'irregularly glandular-serrate' according to the handbook.
R. mollis. leaflet margin.

The margin is certainly irregular with a basic uni-serrate shape but with secondary tips and glandular hairs either forming tips of their own or just stuck on the edge. The handbook description seems perfect.

R. sherardii  Leaflet margin for comparison is rather similar.


R. mollis Petiole and rachis have both short simple white hairs and glandular hairs.

R . mollis. Leaflet stipule has glandular hairs along the margin.


Flowers

R. mollis. Deep pink colour and stigma cluster covers disc.

R. mollis. Stigma cluster covers disc and is about as high as it is wide, forming a dome.

R. mollis.  Sepals are almost simple with few tiny lobes and dense glandular hairs on the outside surface. Hypanthium and pedicle with stalked glandular hairs.

R. mollis. Sepals can be raised to an erect angle.

Pedicles are reported to be 0.5-1.5 cm in the handbook although the photo above shows one at about 2cm. Pedicle length always seems to be quite a variable feature and is supposed to be shorter in mollis than sherardii which has pedicles 1-1.5cm.     

With the above photos to confirm the details I was happy that this example at the Gosforth Nature Reserve is a good example of a Rosa mollis.  However I was lucky to start with such a conforming example and as I travelled on to Allendale and Teesdale the problems of hybrids became much more difficult plus the possibility of R. sherardii and its hybrids.

One plant at Teesdale looked good and  the a few more photos follow below:

R. mollis at Forest-in-Teesdale near the river.

Two key points here are, that the stigma cluster covers the disc and the sepals are almost simple with very limited lobes. This plus the low growth pattern without the arching stems are needed to confirm a R. mollis.  Quite a few plants were found that did not meet this test but still showed many features of mollis.

R. mollis at Forrest-in-Teesdale 

 Same plant as above photo showing quite a short pedicle with long stalked glandular hairs that are also on the hypanthium.

R. mollis type prickles present.

Also nearby were plants that had white flowers but otherwise did seem to tick all the mollis boxes.

R. mollis with white flowers. Forrest-in-Teesdale

Close up of flower showing the stigma cluster covering the disc.


Sepals almost simple.


The handbook does say that white flowered forms of R. mollis can occur and at Teesdale it would appear that both the deep pink and white forms occur.

Problem plants. The following are a few photos of plants that did not have all the required features.

Allendale Town plant.

The stigma cluster does not cover the disc. This and the fact that the prickles were not quite thin enough, suggested this was not a 'pure' mollis.
Allendale Town plant.


The plant was also too tall.  I am guessing maybe this plant is a hybrid possibly with R. canina but the real difficulty is that the shift in features gets close to sherardii which also has a slightly smaller stigma cluster and more curved prickles.  Sherardii is also a taller plant.  With all roses the problem of hybrids makes identification difficult. 
Allendale Town plant.

One feature that suggests a hybrid of R. mollis and R. canina rather than an example of R. sherardii is that the sepals are still quite simple without many lobes.  This plant would need expert attention well beyond my skill level.

Another problem plant was found in Allendale which had a lot of the features for R. mollis but did not have the right growth pattern with arching stems. It also had white flowers.



Not the required shape.

Many mollis type features present but sepals have more lobes than expected. 


Conclusion.

To record a Rosa mollis is not easy. It has features that are close to R. sherardii, so care is needed to make sure all the main features are correct to exclude hybrids and sherardii.  I was lucky that my first plant which I found at Gosforth,  had all the features, as described in the Rose handbook.  Later at Allendale I found more plants, but some were certainly not 'pure'. The only other species of rose present in the area that I found, was R. canina agg.  so I suspect the mollis that had a more canina growth pattern were hybrids with canina
My search for R. caesia Northern Dog Rose was not successful and it is interesting that there are few recent records for this species and one recent BSBI record was, when located,  not accurate as it did not have many of the required features.

Hopefully the above photos are a good representation of what a Rosa mollis should look like and enable others to identify this species.

The main feature of R. mollis are:-
1) Growth pattern, low (2m max) with older plants having near vertical thick stems but without arching stems.

2) Dull leaves, a feature shared with tomentosa and sherardii. Hairy on both surfaces.

3) Prickles that are thin and do not become much wider as you go to the base. The base is large, as if it supports a more normal canina type prickle. Prickles stick out at 90 degrees and are straight or almost straight. Not dense.

4) Sepals are almost simple without lobes ( actually single simple lobes are allowed) plus according to the handbook, can have leaf like extensions. Though I did not find that feature on the plants I found. These leaf like extensions are quite common in many species of rose, where the sepals turn into leaf like extensions suggesting that sepals and leaves are closely connected. 

5) Stigma cluster covers the whole disc or at least most of it whereas sherardii only covers 2/3rds. Both dome shaped unlike tomentosa which has a higher width to height ratio.

Pedicles are short but there is much overlap in this feature with sherardii. One thing I have learnt over the last year is that to determine a rose, you have to check all the features. Some plants tick nearly all the boxes but one feature might not be correct and then you have to re-check with more concentration on the details and take a bigger sample from different stems. Make sure it's the same plant, not two different species with interwoven shoots, which can also confuse.  

Peter Leonard
Rampton Cambridgeshire
11th July 2021



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