Thursday, 13 January 2022

Lanceolate Spleenwort in West Cork

Lanceolate Spleenwort in West Cork.

A search for new ferns while on a winter break in West Cork, December 2021.

 Two possible targets were Irish Spleenwort (Asplenium onopteris) and Lanceolate Spleenwort (Asplenum obovatum).  Both are rarely recorded, especially Irish Spleenwort which has no recent records in County Cork.

Both species hybridise with the variable Black Spleenwort (Asplenium adiantum-nigrum) so some care would be needed in identification, especially as I have no previous experience. A site near Bandon, Keye's Bridge, was checked for Irish Spleenwort, where it had been seen in the past but only Black Spleenwort was found. About ten quite large plants were seen. One possibly might have been showing some intermediate characterises of Irish Spleenwort but more likely was just variation. 

 The new book on ferns, 'Britain's Ferns' by James Merryweather, uses photos taken in Corfu which shows plants of Irish Spleenwort which are more similar to Black Spleenwort than those seen in Ireland. The Irish plants are more extreme in their fine dissection. 

The Keye's Bridge visit did allow me to get more familiar with Black Spleenwort. These were large plants that had fronds with pinna over 20cm of rachis.

Black Spleenwort at Keye's Bridge.  19Dec2021


Black Spleenwort, large frond. 19Dec2021

The two lowest pinna have pinnules that are divided into pinnulets so this large frond is tripinnate.
Smaller fronds are only just bipinnate but all are triangular in outline.

A bit of detail.

Black Spleenwort. Keye's Bridge.  Linear sori are long. 19Dec2021
The sori are covered by a hinged indusia which is at least four time as long as wide, on the longer ones. They are also starting towards the inner side of the pinnulet. 

Black Spleenwort indusia is long and thin and they start near the base of the pinnule/pinnulet.
The one highlighted is measured as six times as long as wide although the ones further out are much shorter. The indusia are hinged along one long edge and cover the sori. 


Black Spleenwort. 27th Dec2021

Notice the stem , called the stipe below the lowest pinna, is dark brown. This dark shinny brown colour goes all the way round the stipe until just below the lowest pinna then fades out to green on the upper side but continues on the back of the frond as a tapering brown line that eventually thins out at least half way up the rachis. See photo below.
Black Spleenwort 27Dec2021. Brown strip tapers out on underside of rachis. 

Why are these features important?  The new target species, Lanceolate Spleenwort, has short indusia.
The shinny red-brown stem ascends the stipe/rachis higher in Irish Spleenwort according to some literature but I have yet to see that feature or the species, to see if it holds true. 

The search for Lanceolate Spleenwort started with research into the British Pteridological Society Bulletin ( Vol 7, 2010 No3 page 198-204), where I found a society visit to West Cork back in 2009. They had found an 'easy to access' colony of Lanceolate Spleenwort on the Kilcatherine area of the Beara Peninsula, not far form where we were staying. There was even a photo showing members taking pictures of Asplenium obvatum subsp. lanceolatum on the wall of a small outbuilding beside the road.
A bit more research using street view on google maps located the outbuilding was still present and that ferns could still be seen growing on it.  It seemed likely that this would be a good place to check out.

On the 31st December I drove to Kilcatherine and found the stone outbuilding. 


It looks as if nothing has changed since 2009. The ferns were still growing on about ten clumps high on the wall. The house has been done up but that's about it. I took photos.

The first thing to say is that these clumps of ferns looked similar to Black Spleenwort but were somewhat different. Late December is probably not the best time of year and they were a bit bashed up but the fronds which stayed close to the wall were still in good condition and even at a distance looked different. Something about the way the terminal pinnae stick out with a clear gap between them and form a ladder each side of the rachis was unlike the Black Spleenwort I had seen earlier that day. Out on the end of the Beara, all these plants are small and the fronds are typically not more than 7cm long compared with the 20cm of the more inland Black Spleenwort (Keye's Bridge, Bandon).  

Lanceolate Spleenwort, 31Dec2021, 

Lanceolate Spleenwort. Detail of frond showing ladder of pinna on each side of the rachis.

Another characteristic which the above photo shows, is that the pinnules on the lower pinna are cut back to the pinna stem making this a bipinnate frond. This is not a useful distinction as the small Black Spleenwort are also often bipinnate ( pinnate to bipinnate to tripinnate). What is slightly more interesting is that the pinnules are rounded (obovate) and have points, like little hands with tiny short fingers.

Shape:


 The most important difference as stated on page 36 of 'Britain's Ferns' is

                                       Lanceolate  Spleenwort                                 Black Spleenwort
Fronds-                          Ovate-lanceolate in outline narrowing             Triangular in outline. broadest
                                       at the base. Basal pinna weakly inflexed.         at the base. 

Pinna -                           lanceolate shape                                               triangular shape
Pinnules-                       obovate shape                                                   lanceolate shape

(Note Obovate , egg-shaped with the broadest part near the apex.)

My photos did not support the pinna shapes as stated above. Maybe this is due to small plant size.

I could see that the Lanceolate Spleenwort has fronds that are not triangular. The pinnae were often triangular in the sense that the pinnules get larger towards the base on the pinna, not lanceolate. These pinnules were rounded/obovate. 

Frond of Lanceolate Spleenwort, Asplenium obvatum subsp. lanceolatum   Kilcatherine, Beara.

The main point is that the frond is not triangular with the lowest pinnae being slightly smaller than the next pair up. I would consider the pinnae to be triangular rather than lanceolate. Maybe larger plants show a lanceolate shape as stated in 'Britain's Ferns'. The lower pinnae are clearly supporting separate (stalked) pinnules (example highlighted in blue), which are quite rounded in shape.  The terminal pinnae are stalked.

The pinnae start off being opposite and become more and more alternate as you go up the rachis. Some fronds had opposite pinnae all the way up but others were alternate for most of the way up. Lots of variation on this feature and it is probably not that useful.  I have yet to see a Black Spleenwort with opposite pinnae going all the way up the rachis. 

Lanceolate Spleenwort. Kilcatherine, Beara.

Another frond which again is lanceolate in outline - certainly not triangular. Pinnae shape not as open on this frond but pinnules are still rounded. Ultimate segments near the apex are stalked.

Lanceolate Spleenwort, Kilcatherine, Beara.

Although the tip of the frond is rather damaged this frond displays the ladder effect of the pinnae sticking out at right angles in a line. Black Spleenwort tends to have more upswept pinnae but this is a marginal feature.

 

Lanceolate Spleenwort. Detail of pinnule showing the serrated outer margin with sharp tips.

Black Spleenwort. Detail showing similar sharp tips which is not always present on some plants. 

Black Spleenwort showing triangular frond outline despite some damage.
Note the terminal segments are wide based rather than stalked at least on smaller fronds, whereas on Lanceolate Spleenwort these terminal segments are more stalked. There is variation as some Black Spleenwort also can have stalked terminal segments.

Black Spleenwort , typical small frond from West Beara. 

Lanceolate Spleenwort. 

The above photo shows the short indusia which are at most, three times as long as wide in Lanceolate Spleenwort.  They also start towards the margin rather than at the base. The tiny hair like scales that are present on the rachis and underside of the pinnules, a feature that Black Spleenwort can also have.

Lanceolate Spleenwort. A more mature frond showing indusia and sori.

The shape and position of the of the indusia are useful in separation of Lanceolate and Black Spleenwort. The above photo shows very short indusia at most three times as long as wide, plus the starting point is further out from the base in comparison to Black Spleenwort.

I made a second trip back to Kilcatherine to double check I really had found Lanceolate Spleenwort and to exclude the possibility that some were hybrids. Black Spleenwort is quite a common plant in the area. More photos were taken and in the end I was happy.

 Something in the shape of the fronds is different even before you look at the outline shape, but is hard to put into words that do not fall foul of the variation between fronds. Size of fronds makes a big difference and all the Black Spleenwort I found this far west, are small. Getting very familiar with Black Spleenwort would seem important before looking for the rare species and I am only starting on this journey.

The good news was that on the 4th Jan on a walk out the road on Dursey Island, I was looking at the Black Spleenwort in the roadside bank when I spotted something different, a Lanceolate Spleenwort growing in a crack between stones in the bank.  A new record for Dursey Island.

Lanceolate Spleenwort, 4th Jan 2022. Dursey Island.

Lanceolate Spleenwort is called Aspenium billotii in  C.N. Page, The Ferns of Britain and Ireland but the scientific name has been updated to A. obovatum.  Two sub-species are known, subspecies obovatum is found in SW Europe and Mediteranean but has not been recorded in the British Isles. It is a diploid whereas A. obovatum subsp. lanceolatum is a autotetraploid. ( ref Plant Crib 1998, BSBI) The Plant Crib has an interesting table to separate Black and Lanceolate Spleenwort including  a comment on habit. 

Black Spleenwort is a plant rarely with a well-formed rosette , with few leaves whereas Lanceolate usually forming a compact rosette of many (15+) leaves amongst old persistent leaves and petioles. I did not count the number of fronds but I think my photos did show these features. Indusia length is noted as 1-3mm in Black Spleenwort and 1-2mm in Lanceolate which does not sound much of a difference but together with the position actually quite a useful ID feature. 

Resources

Page, C. N. (1982) The Ferns of Britain and Ireland.   Cambridge University Press.

Merryweather, J (2020) Britain's Ferns. Princeton University Press.


Peter Leonard

Rampton, Cambridgeshire. 13th January 2022

 






Friday, 26 November 2021

A start into Ferns. Bipinnate or Tripinnate.

A start into Ferns. Bipinnate and tripinnate ?

I started looking at ferns in the autumn of 2020 in West Cork as my normal summer trip had been delayed due to COVID and flowering plants were over their best.

As a complete beginner I made some progress helped by the arrival of the new fern book, 'Britain's Ferns' by James Merryweather which arrived towards the end of my holiday. This new book contains a lot of information and many photographs and is well worth the price of £16.  It does lack some of the detail found in 'The Ferns of Britain and Ireland' by Chris Page which was published in 1982 and has more on hybrids etc. No photos though.

This blog looks at Buckler ferns, as I made basic mistakes in 2020 and missed identifying Broad Buckler- fern ( Dryopteris dilitata).  This was corrected in 2021.

The first reason for going wrong was not understanding the distinction between bi-pinnate and tri-pinnate, which is used a a basic key differentiator in 'Britain's Ferns'. Second reason was not fully appreciating the difference in the size of the pinnule teeth of the Shield ferns vs. the Buckler ferns. 

As a complete beginner, the sheer density of information in 'Britain's Ferns' key was a problem.  Not fully understanding the definition of bipinnate and tripinnate definitely puts you at a disadvantage, along with the fact that this is not a clear distinction in practice.


The above diagram is based on the textbook definition of bi and tri pinnate (Ref.  The Kew Plant Glossary) and is not to scale.  Nor does the shape in the textbook diagram come close to a real fern but it does show the principle.

 If each division were stalked as shown, by the blue Pinnule and purple Pinnulets, it would be fairly straight forward but in real life ferns have a much more complex shape.  In a real fern, the divisions might start off being stalked but become merged, so the distinction between bi and tri has to be based on looking at the lowest pinna rather than the tips. This applies to the pinna division as well as the further pinnule and pinnulet divisions.  An example of these problems is shown in the green highlighted pinnules which show that the pinnules are clearly stalked at the base of the pinna but become merged at the tip. Also the pinnule are segmented into pinnulets at the base of the pinnule but become merged towards the tip.

 The amount of segmentation that forms the pinnulets can cause problems which will be illustrated later using photos.

One suggestion might be that it pays to be methodical. Start with the main frond stem (stipe) and moving up from the base, determine what is a pinna, the first division.  Then move up that pinna and check if the pinnule nearest the stipe is divided into pinnulets, i.e.  separated into distinct sections. This is where it can difficult, as this third division is not always clear cut and this gets worse as you travel up and out on the frond. Also as I will demonstrate later, not all plants conform to the segmentation being complete, even at the base.

Buckler Ferns.

Buckler ferns are tripinnate in 'Britain's Ferns' initial Key. The pinnulets have pointed tips but not as strong as those shown on the bipinnate Shield Ferns. Broad Buckler-fern has the classic shuttlecock form. Separation of the different species of Buckler-fern is difficult but the Broad Buckler-fern normally  has stipe scales that have a dark line through the middle. Separating Buckler ferns species is not the goal of this blog, but it was these dark strips that first alerted me to the correct identification. I had been seeing a Buckler-fern not a Shield-fern. As a beginner with no experience, you can make this type of mistake.

Broad Buckler-fern stipe near the base showing dark centre line.  23Sept21

  Back to the frond detail.

Detailed photo of the pinnule of a Broad Buckler-fern. 23Sept21

I might be breaking my rule to look at the lowest pinna but in this example even the mid pinna show a pinnule (shown outlined in red) has at the base pinnulets, which are segmented right down to the stem of the pinnule (outlined in white). Although the pinnulet base is quite wide and gets wider as you go up the pinnule the segmentation remains 100% until you get close to the tip. This is clearly a tripinnate frond. 


Broad Buckler-fern. Part of pinna near top of frond.

The above photo from the same frond but further up, shows that the pinnule is segmented but only to about 60%.  If you only looked at this part of the frond, the plant might be regarded as bipinnate.  

My first error using the Key was thinking Broad Buckler-fern was bi-pinnate because I was looking too high up the frond.

I wondered if I had found a Shield-fern never having seen a Shield-fern?


Photo showing pinnulet tips follows.

Broad Buckler-fern showing tips to pinnules.


Where it starts to get difficult, is that on some plants only the very lowest pinna and the closest pinnule to the stipe has anything like a full segmentation, all the other pinnules have partial segmentation.
There seems to be a lot of variation in this feature. Some fronds are clearly tripinnate for at least the lowest four pinnae and only above that become bipinnate.


Narrow Buckler-fern ( Dryopteris carthusiana) showing lowest pinnule lacking segmentation into pinnulets. 

The photo above shows the lowest pinna base coming off the stipe. The pinnule is segmented but only the very lowest pinnule next to the stipe is fully segmented right down to near the stem of the pinnule.


Photo of the lowest pinna base with the pinnule closest to the stipe. It shows the first pinnulet
is segmented back almost to the stem, the second segmented to about 90% and the third only to about 80%.  I have highlighted the pinnulet margin in black to show this. The next potential pinnulet out is far less segmented.

 I think the implication of this is that Broad Buckler-fern and probably all the Buckler ferns are variably bipinnate to tripinnate. 
Buckler-fern frond with tripinnate pinnulets highlighted in yellow, all the rest is bipinnate.

Conclusion. It is good to understand the principles behind the terms bipinnate and tripinnate but also be aware that in real life, ferns require a more complex description. It is interesting that Poland and Clements in their 'Vegetative Key to the British Flora' do not use the term bipinnate and tripinnate but use terms like 'Group BH - Lvs 2-3(4)-pinnate for all the Buckler-ferns, Shield ferns and even Bracken.  
I take from this that the Buckler-ferns can be bipinnate through to tripinnate and is therefore not a good fundamental separator to use in a key, as used in 'Britain's Ferns', if you are a complete beginner.  The experts know all this anyway.

To finish-  a few shots of Soft Shield Fern to show the different frond structure and the stiff terminal spines to the tips of the pinnules.

Soft Shield-fern, taken West Cork, 25Sept21

Soft Shield-fern. Base of pinna with pinnules with a thumb. 


Soft Shield-fern. Stalked pinnule with thumb and stiff terminal spines.

The first comment on Soft Shield-fern is that the pinnule is only slightly segmented so this is a bipinnate  frond. The shape is very different to that of a Buckler-fern with a much less symmetrical pinnule, unbalanced by the thumb which has a margin that runs very close to the stem.  The tips have terminal spines which are longer than those on the Buckler-ferns, but this is a variable feature.   I saw my first Shield-fern after returning from Cork in 2020, in late November in a ditch in Cambridge.


References:-
Beentje, H. 2020 The Kew Plant Glossary. (2nd Edn.) Kew Publishing.
Merryweather, J. 2020   Britain's Ferns. Wild Guides
Page, C.N. 1982 The Ferns of Britain and Ireland. Cambridge University Press.
Poland. J & Clements. E.J. 2020 The Vegetative Key to the British Flora.(2nd Edn.) John Poland.
 
Peter Leonard
Rampton
November 2021


Other terms not used:-

 The segmentation of the pinnules is partial and this is called pinnatifid where the depth is not specified, pinnatipartite where segmented to about half way and pinnatisect where divided to almost the midrib.

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