On the 3rd June I had zero knowledge of roses. A chance encounter with Rosa micrantha (when looking at Crested Cow-wheat), initiated a quest to see and photograph all the possible rose species to be found in Cambridgeshire.
The main problem with wild roses is they all hybridise with each other and I took good advice to ignore hybrids, at least to start with. I looked for pure examples of each species, based on the principle that I need to learn the features of each basic species, before one could even consider examining hybrid plants. This involved rejecting examples which did not conform exactly to the handbook description.
I ordered Sell and and Murrell Volume 2 which arrived on the 5th June. This volume contained somewhat disturbing news, quote ' We support John Lindley's remark of two hundred years ago that the study of Roses has been so detailed that one can no longer distinguish species. They are in a taxonomic and nomenclatural mess. All we have been able to do is follow Graham & Primavesi's (1998) Roses of Great Britain for species and hybrids, but we believe that this is a dumbing-down which produces aggregates that could be ecological and geographic non-sense'.
Roses of Great Britain and Ireland, BSBI Handbook No7 by Graham and Primavesi would appear to be a very good starting point despite the rather negative comments by Mr Sell.
Over the summer I have managed to photograph the possible species to be found in Cambridgeshire using the handbook No7 as a guide, in an attempt to find 'pure' non-hybrid examples. Actually all the roses are derived from hybrids and what are regarded as species are just stabilised and widespread plants that share the same features. The BSBI handbook is well laid out, has good line drawings and is concise covering species and hybrids and remains the essential reference text. More recent Dutch work still uses much of its content.
This blog shows leaflet edges of the species and compares them with the stated description in the handbook, as either uni-serrate, bi-serrate or multi-serrate.
Handbook descriptions are stated for each species and the photos compared to see if they agree with that description. Definitions from handbook :-
A) A Uniserrate leaflet has sharp teeth, all more or less the same size.
B) Biserrate is defined as having large teeth, from the lower side of each of which a single smaller tooth arises.
C) A Multiserrate leaflet has large teeth, on the lower side of which, and sometimes also on the upper side, two or more smaller teeth arise, these secondary teeth being usually gland-tipped. This type is not as well defined as the previous ones, because in some cases the secondary teeth are little more than rounded protuberances tipped with glands, and the larger primary teeth are sometimes not noticeably sharp-pointed.
One immediate problem when looking at leaf edges is that there is variation even on a single leaflet, which for example may have uni-serrate teeth on one part and bi-serrate on another.
1) R. arvensis Field Rose
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| Temple dome shape with base convex and concave point. |
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| R arvensis leaflet tip showing dome shape teeth with the tips having a hydathode. |
Described as crenate-serrate. Crenate means rounded. The hydathode is a hard red tip, not glandular.
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| Dome shape only present towards tip of leaflet. |
This is not a clear cut difference but pure R. arvensis tends to have the dome shaped teeth at least on the sides near the tip. Other species share this temple dome shape but the convex base is often not quite as pronounced. Burnet Rose also has these temple dome shaped teeth but it does not occur wild in Cambridgeshire. Some Dog Rose and hybrids also show this dome shape.
A R. arvensis that does not show this shape might well not be pure. Those with occasional stalked glands would suggest some influence of some other species. Note also the example above has some bi-serrate sections which are less temple dome shaped.
Described as uniserrate. R. stylosa shares the dome shaped teeth but not as perfect as in R. arvensis.
Hydrathodes only , no stalked glandular hairs should be present.
Example of a Dog Rose with red tips ( hydathodes) only without any glandular tips. The secondary tips when probed were hard and did not show the normal soft sticky balls that glandular tips have. They seem to be hydathodes rather than glandular hairs. This leaf edge could be regarded as bi-serrate with alternate main teeth and secondary smaller teeth.
Example of a Dog Rose ( possibly a hybrid with R. stylosa) with red tips plus some stalked glandular hairs. This edge might actually fit the description of a bi-serrate edge with its primary teeth and smaller secondary teeth..
Dog Rose is an aggregate of several different variations. The additional problem in Cambridgeshire, is that the Northern Dog Rose R. cassia has hybridised with R. canina and these hybrids are the most common (but variable) plants to be found.
R. canina can have uni, bi and multi serrate leaf edges depending on type although so far I have not found a example with a multi-serrate edge ( group Dumales)
Described as finely biserrate with numerous small, reddish-brown glands on the teeth.
The glands tend to have formed their own tips giving a multi-serrate appearance but note the glandular tips tend to occur on only one side of the main teeth. This might just about pull the description back to being biserrate. Tricky as the clear sides main tooth edge has a single glandular tip on three of the teeth seen in this photo against only two which have no secondary teeth. Secondary teeth, number two rather than the single tooth as suggested in the description of bi-serrate. I think these definitions are starting to struggle with this leaf edge. I would call this multi-serrate because the glandular hairs are generating tips of their own and not just formed straight onto the edge.
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| R. tomentosa |
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| Dog Rose |
2) R. stylosa Short-styled Rose
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| R. stylosa showing Uni-serrate edges |
Hydrathodes only , no stalked glandular hairs should be present.
3) R. Canina agg. Dog Rose
Example of a Dog Rose ( possibly a hybrid with R. stylosa) with red tips plus some stalked glandular hairs. This edge might actually fit the description of a bi-serrate edge with its primary teeth and smaller secondary teeth..
Dog Rose is an aggregate of several different variations. The additional problem in Cambridgeshire, is that the Northern Dog Rose R. cassia has hybridised with R. canina and these hybrids are the most common (but variable) plants to be found.
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| Dog Rose showing that different parts of a leaf may have a different types of edge. |
4) R. obtusifolia now called tomentela Round-leaved Rose.
Described as finely biserrate with numerous small, reddish-brown glands on the teeth.
The glands tend to have formed their own tips giving a multi-serrate appearance but note the glandular tips tend to occur on only one side of the main teeth. This might just about pull the description back to being biserrate. Tricky as the clear sides main tooth edge has a single glandular tip on three of the teeth seen in this photo against only two which have no secondary teeth. Secondary teeth, number two rather than the single tooth as suggested in the description of bi-serrate. I think these definitions are starting to struggle with this leaf edge. I would call this multi-serrate because the glandular hairs are generating tips of their own and not just formed straight onto the edge.
This example has glands on the underside but this feature is lacking in several of the Cambridgeshire sites.
This example has very round leaflets but this does not guarantee a obtustifolia as hybrids can have same rounded shape. The edge appears very spiky as the teeth are quite narrow.
The small leaflets have some tendency towards a bi-serrate edge but it is not consistent. Leaflet shape not quite so round but still typical, with lots of overlap and hairs on both sides.
Many plants are hybrids Rosa canina x obtusifolia ( R. x dumetorum) so it is quite hard to find examples that really fit with Round-leaved Rose 100%. The leaflets overlapping is probably more important than the rounded shape which is present in some of the hybrids. R. obtusifolia leaflets tend to have a dark shinny green surface with at least some white hairs on upper surface although canina agg. can have some white hairs on upper surface but normally limited to near the mid-rib. Not an easy species to nail down and not common at all in Cambridgeshire. Most of the plants at Gamlingay Wood were not 100% conforming to the required feature set of Round-leaved Rose, but a couple of plants on the east edge did seem to fit.
Described as strongly glandular-biserrate. This photo above does show a bi-serrate edge. A second leaf photo below does show this with primary teeth and slightly smaller secondary teeth. It is certainly strongly glandular.
The bi-serrate edge is clear with many glandular hairs on the edge which rarely form a point of their own. R micrantha seems to have glandular hairs that form tips but at a low density, but a much larger sample of plants would be needed to see if this feature is consistent and it's a very subtle difference given the leaf to leaf variation. Whereas R. rubiginosa seems to have a bi-serrate edge, R. micrantha seems to lack this being multi-serrate. Probably not a reliable difference but worth looking for.
Described as irregularly biserrate.
Underside of leaflet very hairy with white matted hairs. Edge has red tipped hydathodes on the teeth tips and the teeth sides have short stalked glandular hairs which are mostly formed on small teeth of their own. Zero to a maximum of three glands per trailing edge tooth side. The leading or clear edge of each primary tooth in this case has no glandular hairs.
Biserrate is defined as having large teeth, from the lower side of each of which a single smaller tooth arises. It is a fine distinction to multi-serrate. In this example the primary large teeth are dominant whereas the next species examples of multi-serrate edges, the secondary glandular tips make the primary teeth less dominant.
This is partly down to tomentosa having fewer glandular tips.
Note the lack of tiny glandular on the underside leaf surface which are hard to see at the best of times but appear to be missing in many R. tomentosa in Cambridge. Sometimes a few leaves have the tiny stalked glands whereas as many lack them on the same plant. Due to the hairs on both sides of the leaflet it can be hard to see the margin clearly but in conclusion I would say the leaf edge is bi-serrate to multi-serrate so irregularly biserrate is not far off.
Described as glandular-multiserrate.
Red hydathode tips as usual plus glandular short stalked hairs on tiny teeth (most of the time) do give a multi serrate look to the leaflet edge. Between one and four glandular hairs per main tooth side. Glandular tip quite variable in size. A rather messy edge.
Described as glandular-multiserrate. The tips have the usual red hydathodes and short stalked glandular hairs which are on the sides of the teeth without forming a separate tip of their own. One to four glands occur on each side of the tooth. In some ways the leaflet edge is uni-serrate with additional glands as these glands only have formed on tiny teeth of their own to a very limited extent.
Without this level of magnification the leaflet edge would look glandular multi serrate. No clear edge of the main teeth appears with secondary glandular teeth on both sides although the shape indicates the right hand edge is the clear one which on average also has less glandular hairs. The leaflet tip will be to the right, indicated by the clear edge being on the right hand side.
Conclusion.
The descriptions for bi- and multi serrate are tricky. This is recognised in the description on Multi-serrate in the handbook and I suppose the authors were somewhat constrained by previous work.
The think the main problem is due to the glandular hairs either just being on the leaflet edge or forming a point on their own. If the point is large you get the multi-serrate appearance even if the basic leaf edge is uni-serrate or bi-serrate. The example above for R. agrestis has a basic uni-serrate edge with all primary teeth the same size. The glandular hairs are mainly not forming any tips and the few that do are tiny. Because the glands are quite large in the field this edge would look multi-serrate but when enlarged and looked at in this level of detail a better description might be uni-serrate with additional glands. And that is before we consider variation.
I can't say I have found any new insights into separating these species but I am now at least more aware of the current descriptions and will pay more attention next season. Hydrathodes are solid whereas glandular hairs have a ball of sticky stuff at the tip but as the glandular hair ages it will lose some of its stickiness so that it can be hard to tell them apart unless examined under a microscope. As ever, you can't name a rose by only looking at its leaves, as all features have to be examined.
Peter Leonard
23rd August 2020
Rampton
Cambridgeshire.
Update More pictures of R. micrantha.
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| R. obtusifolia 22nd June Burton End, Cambridgeshire |
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| R obtusifolia. 5th July 2020 Gamlingay Wood. |
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| R. obtusifolia except middle hybrid leaf. 4th August Gamlingay Wood |
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| R. obtusifolia except middle hybrid leaf. 4th August Gamlingay Wood |
5) R. rubiginosa Sweet Briar
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| Glandular hairs are stalked and often do not form tips on leaf edge. |
The bi-serrate edge is clear with many glandular hairs on the edge which rarely form a point of their own. R micrantha seems to have glandular hairs that form tips but at a low density, but a much larger sample of plants would be needed to see if this feature is consistent and it's a very subtle difference given the leaf to leaf variation. Whereas R. rubiginosa seems to have a bi-serrate edge, R. micrantha seems to lack this being multi-serrate. Probably not a reliable difference but worth looking for.
6) R. micrantha Small-flowered Sweet Briar
Described as glandular multi serrate. I would agree as the glandular hairs are often forming their own tips but the quantity of glandular hairs is quite low with typical just one on the leading edge and two on the trailing edge.
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| R. micrantha showing glandular hairs on tips. |
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| R micrantha showing sparse glandular tips without stalks. |
7) R. tomentosa Harsh Downy Rose
Underside of leaflet very hairy with white matted hairs. Edge has red tipped hydathodes on the teeth tips and the teeth sides have short stalked glandular hairs which are mostly formed on small teeth of their own. Zero to a maximum of three glands per trailing edge tooth side. The leading or clear edge of each primary tooth in this case has no glandular hairs.
Biserrate is defined as having large teeth, from the lower side of each of which a single smaller tooth arises. It is a fine distinction to multi-serrate. In this example the primary large teeth are dominant whereas the next species examples of multi-serrate edges, the secondary glandular tips make the primary teeth less dominant.
This is partly down to tomentosa having fewer glandular tips.
Note the lack of tiny glandular on the underside leaf surface which are hard to see at the best of times but appear to be missing in many R. tomentosa in Cambridge. Sometimes a few leaves have the tiny stalked glands whereas as many lack them on the same plant. Due to the hairs on both sides of the leaflet it can be hard to see the margin clearly but in conclusion I would say the leaf edge is bi-serrate to multi-serrate so irregularly biserrate is not far off.
8) R. sherardii Sherard's Downy Rose.
Described as glandular-multiserrate.
Red hydathode tips as usual plus glandular short stalked hairs on tiny teeth (most of the time) do give a multi serrate look to the leaflet edge. Between one and four glandular hairs per main tooth side. Glandular tip quite variable in size. A rather messy edge.
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| R. sherardii 1st September 20 Fourwentways. Cambridgeshire |
9) R. agrestis Small-leaved Rose
Without this level of magnification the leaflet edge would look glandular multi serrate. No clear edge of the main teeth appears with secondary glandular teeth on both sides although the shape indicates the right hand edge is the clear one which on average also has less glandular hairs. The leaflet tip will be to the right, indicated by the clear edge being on the right hand side.
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| R. agrestis 22nd August 2020 |
Conclusion.
The descriptions for bi- and multi serrate are tricky. This is recognised in the description on Multi-serrate in the handbook and I suppose the authors were somewhat constrained by previous work.
The think the main problem is due to the glandular hairs either just being on the leaflet edge or forming a point on their own. If the point is large you get the multi-serrate appearance even if the basic leaf edge is uni-serrate or bi-serrate. The example above for R. agrestis has a basic uni-serrate edge with all primary teeth the same size. The glandular hairs are mainly not forming any tips and the few that do are tiny. Because the glands are quite large in the field this edge would look multi-serrate but when enlarged and looked at in this level of detail a better description might be uni-serrate with additional glands. And that is before we consider variation.
I can't say I have found any new insights into separating these species but I am now at least more aware of the current descriptions and will pay more attention next season. Hydrathodes are solid whereas glandular hairs have a ball of sticky stuff at the tip but as the glandular hair ages it will lose some of its stickiness so that it can be hard to tell them apart unless examined under a microscope. As ever, you can't name a rose by only looking at its leaves, as all features have to be examined.
Peter Leonard
23rd August 2020
Rampton
Cambridgeshire.
Update More pictures of R. micrantha.
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| R. micrantha 28th October 2020. Castle Camps, Cambs. |
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| R. micrantha 20 Oct 20 Langley Wood, Cambs |
