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. 

Blue Composites, Chicory and Blue Sowthistle

 Blue Composites, Chicory and Common Blue Sowthistle.

A few photos of these two blue flowered composites.

The blue stamens look amazing with their dark blue edging. The white pollen coating the style and onto the curved stigma.  Chicory 12 July 2020, Guided Bus, near Rampton. 

Chicory, quite a tall thin plant with flowers on short stalks in clusters up the stem.

Basal leaves are lobed.

Stem leaves clasp the stem and have jagged edges.

Open flower plus new buds. 

Phyllaries in two rows, outer wide and overlapping. Ligules have glandular hairs which is an unusual feature of this species.  Chicory  12 July 2020

A similar species to Chicory (Cichorium intybus) in the UK is the Common Blue Sowthistle ( Cicerbita macrophylla) which is also regarded as a garden escape and is widespread in the UK. I had never seen one until a visit to the Peak District in August.

Pale mauve flowers about 30mm across. Common Blue Sowthistle, Peak District. 7th Aug 2020

Outer phyllaries overlapping and of very different lengths and have pale margins. Glandular hairs on phyllaries and stem but not on the pale mauve ligules.  

Mid Stem leaf clasping the stem with neat fine teeth on margins.

The Common Blue Sowthistle is a much more leafy plant than Chicory.  It originally came from the Urals. There are three other species of Blue Sowthistle in Britain, the native Alpine Blue Sowthistle found in a few high mountain gullies in Scotland, Hairless Blue Sowthistle a very rare garden escape from the Pyrenees and southern Europe and finally Pontic Sowthistle another garden escape from Georgia and north-eastern Turkey.

Peter Leonard, Rampton, Cambridgeshire, 7th Feb 2021

Hieracium aviicola Many-toothed Hawkweed

 Hieracium aviicola   Many-toothed Hawkweed    Devils Ditch. Newmarket Heath.

Hawkweed on Devils Ditch, Newmarket Heath, Cambridgeshire.

There is a new Hawkweed book, Hawkweeds of South-East England by Mike Shaw recently published by the BSBI. It builds on the previous work by Vincent Jones with the ground breaking Yorkshire Hawkweeds published by the Yorkshire Natualists Union, now out of print.  Between these two books a large number of the hawkweeds in England can now be identified in theory. In practice the identification of Hawkweeds remains difficult. I had an advantage when shown this Hawkweed, in that I was with Alan Leslie (who has recently written the new Flora of Cambridgeshire, RHS 2019) and he knew what species it was. He had seen it in the past at this site and also knew that Peter Sell ( Co-author of Flora of Great Britain and Ireland, vols 1-5) had been involved in the original confirmation. Peter Sell was a great enthusiast and expert on Hawkweeds. He grew many Hawkweed species in the Cambridge Botanic Gardens to study them in detail.

The question is could I have, as a 'Hawkweed beginner' identified it myself, based on the photos I had taken?

Both books on Hawkweeds have keys and both books cover H. aviicola. I used the South-East England book as a test.

The first item in any Hawkweed identification is to check whether the plant has basal leaves when in flower and then the number of stem leaves. The photo above shows the basal leaves are certainly present and in full health. The single stem has three stem leaves and a fourth that might be regarded as a inflorescence bract. There is also a higher bract. The count of stem leaves plus inflorescence bracts going up one stem path is important, as the first question in the Key is are there more or less than eight.

We have five (maybe six) here.

The other factor is: Does the plant look well, robust and undamaged? - It does. 

Next key question is: Are the leaves covered in glandular hairs to exclude a group called Amplexicaulia?

Basal leaves.

These basal leaves have a few white hairs mainly along the margin and very few on the lamina surface.

So not Amplexicaulia.  Note the  basal leaves have quite a long petiole and have quite short teeth.

The next question relates to number of stem leaves. 

Stem leaves 0-1(2) : basal leaves numerous  in which case go to Hieracium group.

Stem leaves 2-8 : basal leaves usually few in which case go to group Oreadea or Vulgata.

We have about 5 stem leaves/bracts so looks like we can exclude Hieracium group. Also basal leaves are few but this seems a bit vague and a number would be better.

Oreadea has phyllaries that have predominant eglandular hairs whereas Vulgata has a mixture of eglandular and glandular hairs but glandular hairs usually predominant.

Glandular hairs predominant.

Phyllaries clearly are covered in glandular hairs so it looks as if the Hawkweed we have here is in the Vulgata group.

We hit two problems at this stage, one is that there are a lot of species in the Vulgata group and some are grouped together as aggregates as they are so similar. This is where the Vulgata key in the South-East England book fails, as its key does not include the aggregate groups ( H. maculate agg. , H. diaphanous agg., and  H. acuminatum agg.). These groups are covered but not linked by the key.

Fortunately in the Yorkshire book, Vulgata key does include aggregate groups (on page 101). 

I now use the Yorkshire book and its key.

Leaves unspotted takes us onto phyllaries with predominant glandular hairs and then we get into real detail. 

The next key split is dependent on the density of stellate hairs on the phyllaries. The photo above does show some stellate hairs but more magnification is needed.

Stellate hairs ( I normally call these cobwebby hairs)

Stellate hairs are certainly present especially on the margins of the phyllaries which moves us onto

the next question. Do the upper stem leaves have stellate hairs present on the lower surface? 

Lots of simple white hairs but no sign of any stellate hairs on the lower surface.

At this point the size of the teeth on the leaves come in and section 9 of the key gives following choice:-

Leaves entire to denticulate or with small teeth.                                            10

Leaves obviously dentate, often with mammiform teeth.                               H. acuminate agg.

-entire is lacking teeth, 

-denticulate means with regular small fine patent teeth, evenly spaced.

-dentate  means with large more or less patent teeth.

-mammiform with more or less rounded teeth which can vary in size and are pointed at the tip.

First problem here is what leaves are they referring to , basal leaves or stem leaves. I assume stem leaves. The basal leaves have quite small teeth but the stem leaves have quite pronounced teeth.

I would regard the teeth on the above stem leaf is large and pointed so I think we have arrived at 

H. acuminate agg. Having said that, there was a population of about 20 plants and there was quite a lot of variation in teeth size.

Whether we should just stop at H. acuminatum agg. rather than try and spit this group further is a good question. We all know that plants within a species can vary considerably in various features but strangely many Hieracium 'species' apparently have very little variation and this is some ways justifies their status as species.  It would seem we have been using quite tiny changes to arrive at H. acuminate agg.  The justification for continuing to split further would have to be based on consistent features over a geographical range. This would appear to be the case for these vulgata hawkweeds, which is the case of H. aviicola are widely recorded across England and Wales.

 These species reproduce by selfing, i.e. producing clones.  As a hawkweed beginner, all I can do is see how far I can go using these new books and see if I can work out  if the description and photos I have taken tie up with the description in the literature. 

The following species make up the H. acuminatum agg. :-

(H. acuminatum)    

H. consociatum

H. argillaceum

H. aviicola

H. nemophilum

H. chlorophyllum

H. festinum

H. cheriense

No Key is provided in the South-East England book but the Yorkshire book does cover the five species seen in Yorkshire, which includes H. aviicola. The leaf shape and dentition seems to be the main difference.

Basal leaf shows quite limited teeth 

Lower stem leaves seem to vary in the amount of teeth depending on what plant you look at.

This example has very limited teeth but is does vary from leaf to leaf.

Mid-stem leaf  July 2020 Devils Ditch. Newmarket.

A different plant in the same population has teeth that are very narrow and quite long.

The key talks about the teeth being longer than 6mm ( up to 10mm on stem leaves) or less than 6mm.

I think the plants at the Devils Ditch are typically below 6mm which leaves H. argillaceum, H. aviicola, and H. nemophilum.  At this point the very first photo shows the stem leaves gradually decreasing in size upwards which fits with H. aviicola. Result, happiness!- but the differences between these three species is very small in the terms of the key descriptions. 

In practice I looked at other features not in the key, to confirm the identification by reading the notes and photos about H. aviicola is both books.  The leaves tend to taper at both ends which fits in with the choice of all three species in the sub-group. 'The inflorescence with long lower branches from the leaf axils and with the lower peduncles making a wide angle with the stem and the upper being more or less erect, giving a large, broad panicle' fits well with H. aviicola and this is apparent in the structure seen in the very first photo and the photo below. However I lack experience of the other two species.

Styles are stated to be yellow in the Yorkshire and the South-East England books, so that matches with photo below.

Yellow stigma

In truth, without knowing what the species at the start ( thanks to Alan Leslie),   I would have struggled, in this final stage to get to the right result.  In reality you would need a lot of hard earned practice to get the expertise required.  This is hard to achieve but both books give sites where you can observe the various species and that it probably the only way to improve one's knowledge.  Both these regional books have great photos of example plants and these give as much insight as the keys, when you get close to the solution. Sometimes keys fail however and then a more multi-feature approach is needed.

 Early days but I have learnt a bit more on the detail needed to identify these difficult Hawkweeds. I suspect that this Vulgata group are not the easiest to make a start with. Without the books by Vince Jones and Mike Shaw I would not stand a chance. 

Resources:-

Hawkweeds of South-East England by Mike Shaw, BSBI Handbook No 20.

Yorkshire Hawkweeds by Vincent Jones , Yorkshire Naturalists' Union.

Flora of Great Britain and Ireland, Vol 4 by Peter Sell and Gina Murrell.   

Pedicles have stellate and glandular hairs.  7th July 2020

Peter Leonard

Rampton, Cambridgeshire.

22nd January 2021