Rosa stylosa. Short-styled Field Rose in Cambridgeshire.

Rosa stylosa   Short-styled Field Rose in Cambridgeshire.

In my quest to photograph all the wild roses in Cambridgeshire (during the summer of 2020), R. stylosa was not an easy species to find.  The recent Flora of Cambridgeshire by Alan Leslie,  points out that it is often recorded as a hybrid with R. canina in scattered sites across the south of the county. Since this is my first season looking at roses,  I was attempting to avoid hybrids and concentrate on learning the basic species first.  The first record for Cambridgeshire from C.C. Babington was redetermined by A.L. Primavesi as R. arvensis x canina so that was another warning that this species might not be straightforward.

As ever, my reference book for this task was the excellent Roses of Great Britain and Ireland , BSBI Handbook no 7 by G.G. Graham and A.L. Primavesi published in 1993, plus a lot of help from Alan Leslie.

R. stylosa, 15Jun2020. Fen Drayton, Cambridgeshire.

Context.

The field guides tend to group the two 'Field Roses' together, R. arvensis and R. stylosa although R. arvensis is one of very few roses in the UK that is not in the section Caninae (unbalanced polyploids). R. arvensis is in section Synstylae whereas  R. stylosa is in the section Caninae and the sub-section Caninae with Dog Roses R. canina and R. caesia. Various papers on the evolutionary history of all these stable species show they shared parents in the past (through hybridisation) and never separated enough to stop hybridisation occurring currently. 

R. stylosa 15Jun2020. Species gets its name from the fused short style.

R. stylosa.

Upper arrow points to the stamen and anthers which are a similar height to the fused style whereas the fused style in R. arvensis is taller being longer than the stamen.

R. arvensis.

Upper arrow points to the fused style of R. arvensis raising the stigma above the level of the stamen and anthers ( second arrow).  The lowest arrows show the conical disc in R. stylosa and the flat disc in R. arvensis although I now think the conical disc is under drawn. The styles in R. stylosa are slightly different lengths so that the stigma cluster is taller in shape than the more domed shape in R. arvensis.

R. stylosa 11Aug2020. Conical disc and fused style starting to come apart.

R. stylosa, 18Oct2020

A late season photo shows the conical disc and the fused style of R. stylosa.

R. arvensis. 20Oct2020

A late season photo shows the flat disc and long fused style of R. arvensis. The hip is typically more soccer than rugby in shape and the pedicle longer. The glandular hairs on the pedicle are almost gone at this stage.

Rosa arvensis is a distinctive species in that it has weak thin stems (often green or purple) that climb through hedges or trees at the edges of woods, often in shady places. R. stylosa is a more typical structure with strong arching stems much like other Dog roses.

R. stylosa. 15Jun2020 

A key feature of both R. arvensis and R. stylosa is that the pedicle has glandular stalked hairs. These hairs are typically shorter than those found in the Downy roses and quite sparse in R. stylosa.  

R. stylosa. 15Jun2020, Bract, pedicle and sepal.

Above photo showing the pedicle below the hypanium with glandular tipped hairs. The sepal is pinnate,  the lobes typically simple without additional side protrusions, although some glandular tipped side protrusions may occur as seen in the photo below on the lower two protrusions.

R.stylosa 11Aug2020, Sepal , very few glandular hairs on margin and long 1.5-2cm.

R. tomentella ( was obtusifolia) Bi-pinnate sepals for comparison. Protrusions on protrusions.

Leaves.

R. stylosa 15Jun2020 Leaf with widely spaced leaflets with lowest often reflexed, tapering to an acute apex. Leaflets are 2-2.5 X as long as wide.

R. stylosa 11Aug2020 

R. stylosa 18Aug2020. Reflexed lower leaflets.

R. stylosa 11Aug2020, Leaf stem , petiole and rachis have stalked glandular hairs and pricklets.

R. stylosa 15Jun2020. Leaflet edge is uni-serrate with red tipped hydathodes

R . arvensis leaf edge with temple dome shape.

The leaflet edge is uni-serrate (occasionally bi-serrate) and has the temple domed shape ( convex to concave) to each tip but less pronounced than in R. arvensis with almost straight tip edges on many in the photo of R. stylosa. This shape is seen in some R. canina Dog Rose.  No glandular hairs on the margin in these photo although it can occur in R. stylosa. 

R. stylosa Leaflet lower surface with white hairs on midrib and secondary veins.

R. stylosa, 15Jun2020 

Deltate prickles on mature stems, a wide base with a triangular shape with either a straight or curved tip.

R. stylosa hybrid 28Jun2020 Orwell.

R. stylosa hybrid 28Jun2020 Orwell.

Although I am avoiding hybrids in an attempt to learn the basic species first, it is easy to get caught out when looking at roses.  The above photo shows the fused stigma and conical disc that made me think this was a R. stylosa. The important message is that you cannot rely on a single feature and the leaves on this plant showed a problem. Other features also did not quite tie up with R. stylosa either.

Hybrid leaflet. 28Jun2020 Orwell.

This leaflet is not correct for a R. stylosa with red tipped glandular hairs on the underside of the leaflet and red-tipped stalked glandular hairs on the leaflet margin.  The edge is multi-serrate and this hybrid is not the common Canina x stylosa (or Stylosa x canina)  and would need expert evaluation. 

R. stylosa 20Oct2020 Hip cut in half to show narrow orifice and thick conical disc.

Conclusion. 

These photos do not show every feature of Short-styled Field Rose ( R. stylosa) but hopefully show some of the important details of this species. The short stalked glandular hairs on the pedicle and the shape of the fused stigma being about the same or below the height of the stamens and the uni-serrate leaf margin are the key features. This is backed up by the sharply pointed dark green leaflets which are well spaced on a petiole and rachis that have stalked glandular hairs. The lowest leaflet pair are often reflexed but not all my photos show this feature well, as it does vary plant to plant. Some versions of the Dog Rose (R. canina) can have the conical disc and similar shape to the style and hybrids are often recorded.

 In some ways R.stylosa fits somewhere between R. arvensis and R. canina but in my first season looking at roses, I think I have achieved some progress in all the species in Cambridgeshire, except R. canina. 

Dog Rose (R. canina) and its hybrids with R. caesia form a very difficult group which I have failed to untangle. The term R.canina agg. might come in useful.

Peter Leonard

28th March 2021

Rampton , Cambridgeshire.

Rosa sherardii. Sherard's Downy Rose in Cambridgeshire

Rosa sherardii. Sherard's Downy Rose in Cambridgeshire.

This blog shows a few photographs taken in my quest to learn about roses to be found in Cambridegeshire during the summer of 2020. 

According to the 'Flora of Cambridgeshire',  Alan Leslie 2019, there is only one current place where this species is found-  by the A11 at Four Went Ways. There were other records in the past in other locations but some were later considered to actually be Rosa tomentosa (Harsh Downy Rose), which suggests that telling these two species apart is not easy. 

Both these downy roses are in the section Caninae which mean they have the unbalanced breeding system in which the female parent contributes four sets of chromosomes to the progeny, whereas only one set comes from the pollen (male) which fertilises it. All these roses hybridise now and it is thought that all the current stabilised species today, were derived by hybridisation in the distant past.  The Downy roses are in sub-section Vestitae  which also includes R. mollis (Soft Downy Rose) which is a more northern species as far as the UK goes. R. mollis is not found in Cambridgeshire, nearest place being the Peak District. 

R. sherardii, 12 June2020, Four Went Ways.

First comment on this flower is the deep pink colour. The only other rose that gets close to this deep pink in Cambridgeshire would be R. rubiginosa (Sweet Briar). 

R. rubiginosa 10Jun2020 Devils Ditch. Reach.

R. tormentosa has a much paler pink flower.

R. tomentosa, 9Jun2020, 

Flower colour is not the most important feature that separates the Downy roses, which is the hairy leaflets. Flower colour in R sherardii according to the 'Roses of Great Britain and Ireland' BSBI Handbook No 7 by Graham and Primavesi (which is the standard reference) can be white in Scotland.  

R. sherardii, 12Jun2020, underside of leaflet.

The underside of the leaflets is densely hairy, a feature sherardii shares with tomentosa. It also has lots of glandular hairs which in the case of the sherardii at Four Went Ways are easy to see. In some tomentosa it is even more densely covered in hairs so that it is difficult to see the tiny glandular hairs. The density of these glandular hairs can be variable according to the literature.

R. tomentosa 19Jun2020. 

R. tomentosa 19Jun2020. Just a very few glandular hairs only just visible amongst the hairs.

R. rubiginosa has lots of glandular hairs but the glands are much larger and the density of the simple white hairs is less. The diameter of the largest glands is 0.1-0.12mm whereas the Downy roses have glands 0.05mm diameter and can also have a stalk. This is according to the handbook and was confirmed using a calibrated magnifier.

R rubiginosa showing stalked glandular hairs on underside of leaf. 15Aug2020 Swavesey.

R. rubiginosa Underside of leaflet showing glandular hairs and simple hairs.

Leaves.

R. sherardii,  note simple hairs on upper surface and glandular margin.

R. sherardii, 12Jun2020 Upper side of leaf.

R. sherardii, Underside of leaf.

R. sherardii, 12Jun2020. Stipule at base of leaf.

The particular group of Sherard's Downy Roses at Four Went Ways has an abundance of red glandular hairs. This is not always the case as I discovered when I visited Cork, Ireland in September. The stipule above has the normal glands along the margin but also all over the lower surface, whereas in Cork the glandular hairs just ran along the margin like many other species of rose.

 The leaflet stem ( petiole and rachis) have glandular hairs plus white simple hairs.

R.sherardii, 12Jun2020. Leaf edge.

The leaflet margin can be described as Multi-serrate with stalked glandular hairs having tips of their own in some cases. According to the handbook, R. sherardii can show quite a lot of regional variation, so sometimes the the underside of the leaflet can almost lack the soft white hairs and the glands.

R sherardii, 12Jun2020, Four Went Ways

The photo above shows the top of the flower stem (pedicle) and hypanthium (hip) with with long glandular tipped hairs. In this population the ball like tips are a deep red colour. To the right of the pedicle is a bract which also has lots of red tipped short glandular hairs on the margin and across much of its surface.

R. tomentosa. 22Jun2020 

Comparison shot of R. tomentosa showing the pedicle and hypanium have the same long glandular hairs.

The stipule has red tipped short glandular hairs along the margin like many species of rose.

R. tomentosa 24Jun2020 Post flowering photo showing pedicle, hypanium and sepals.

R. sherardii 12Jun2020  Post flowering photo showing pedicle, hypanium and pinnate sepals.

Not a lot to choose between these photos of the pedicle, hypanium and glandular hairs, as many of the features are similar. The stalk ( pedicle) for R. sherardii is supposed to be shorter 1-1.5cm compared to R. tomentosa at (1.5)2-3.5cm but I am not sure how reliable pedicle length is, as in my limited experience pedicle length can vary a lot even on a single stem.  

R sherardii, 12Jun2020 stigma cluster.

The stigma cluster is large, almost covering the disc - to 2/3rds- and domed with a few hairs. The disc is almost flat.

R. tomentosa 19Jun2020 Stigma cluster.

The stigma cluster is smaller so you can see more of the disc. It is taller and less domed in shape but also has the odd hair (many to none).  Disc is almost flat. This is a subtle feature and it would be interesting to take more photos of each species at more sites, to see if there is a consistent difference.

R. sherardii, 1Sep2020, Rounded hips have very deep red colour. 

R. canina Dog Rose, 1Sep2020 comparison shot.

Note the sepals remain on the R. sherardii whereas they have fallen on the Dog Rose at this stage. The R. sherardii are an amazing deep red which is not really shown to its full extent by the photos. Below is R. tomentosa which, according to the Handbook, should have lost its sepals by this stage of the hip turning red. It has previously been noted by Chris Preston in his review of The genus Rosa in Cambridgeshire (v.c. 29) an interim account, that some local bushes of R. tomentosa have persistent sepals. 

R. tomentosa. 14Oct2020

R. sherardii, 15Sep2020 Castletownbere, West Cork , Ireland

Final photo shows the shiny round red hips as the season comes to an end. They are not always so round in shape. By this stage the glandular hairs have lost their red tips which have turned grey and dried up. 

Conclusion. 

In my first season of looking at roses I think I can identify the two downy roses, R sherardii and tomentosa but need to be careful of hybrids. It is easy to miss the slightly aberrant features of hybrids, which require expertise beyond one season's learning.  Also I have little experience of regional variation which is a feature of R. sherardii, so more to learn plus I have not seen R. mollis yet. Hope to travel north to find R. mollis when lockdown is over in June.

Peter Leonard

Rampton, Cambridgeshire.

10th March 2021

R. tomentosa stigma cluster slightly taller than wide. Devils Ditch

R. tomentosa, Ditton Park Wood. 24Jun21

R. tomentosa 22Jun21. Devils Ditch

R. sherardii , flat disc, hairy stigma covering about half the disc at this stage.
Note pinnate side lobes, with two on the left sepal side in view.

R. sherardii, domed stigma cluster not as tall as R. tomentosa, Cambridge, Four Went Ways

R, sherardii Stigma cluster about as wide as tall.

Variation in prickles.

R. sherardii, almost straight.

R. sherardii, a more curved example. Shape slightly concerning but it is good to check several stems and see how much variation is present. This plant had mainly straighter prickles.

R. sherardii. Younger prickles.

R. sherardii, younger prickles.

The handbook suggests that although normally the prickles have weak bases some populations have stronger more curved prickles. The above prickle photos were all taken at Four Went Ways.

The variation in prickles from being thin and straight ad patent through to curved with slightly thicker bases is important as R. mollis has all prickles thin, straight and patent. It is worth checking several stems to see how much variation occurs.

For R. mollis see new blog under Rose label.