Sunday, 7 April 2019

Viola reichenbachiana and V.riviniana Hybridise?

Common ( V. riviniana) and Early Dog ( V. reichenbachiana) violets have been a much debated subject in regard to intermediate plants being either variation or the result of hybridisation.

The BSBI Viola handbook covers the problems and attempts to provide a practical approach based on morphological features but concludes 'more work needs to be undertaken on the taxonomy of this group'.

I found a paper on the internet (abstract only unfortunately ) that has an interesting claim that in Europe there is no evidence of hybridisation, or that's what I understand it means. Whether this result would apply to plants in the UK is not known.  The paper was written in Eastern Europe and the UK appears not to have been one of the four countries sampled. (I have not been able to review the full paper and would not have the knowledge to understand it anyway. )

It was published in the July 2017 edition of Plant Biology.  The abstract is below the following photos of Viola reichenbachiana variation.  These plants had quite pale spurs and remarkably sharp ends to the purple veins but within the limits of variation. Short sepal appendages well within normal range of V. reichenbachiana. Just an example of variation in Early Dog Violet.

Viola reichenbachiana with quite pale spur , Brinkley, Cambridgeshire, 6th April 2019
Viola reichenbachiana with clear ends to dark veins. Brinkley, Cambridgeshire, 6th April 2019

Plant Biol (Stuttg). 2017 Jul;19(4):542-551. doi: 10.1111/plb.12571. Epub 2017 May 17.No evidence of contemporary interploidy gene flow
between the closely related European woodland violets
Viola reichenbachiana and V. riviniana (sect. Viola,
Migdałek G1Nowak J2Saługa M2Cieślak E2Szczepaniak M2Ronikier M2Marcussen T3Słomka A4Kuta E4.Author information
Viola reichenbachiana (2n = 4x = 20) and V. riviniana (2n = 8x = 40) are closely related species widely distributed in Europe, often sharing the same habitat throughout their overlapping ranges. It has been suggested in numerous studies that their high intraspecific morphological variability and plasticity might have been further increased by interspecific hybridisation in contact zones, given the sympatry of the species and the incomplete sterility of their hybrid. The aims of this study were to: (i) confirm that V. reichenbachiana and V. riviniana have one 4x genome in common, and (ii) determine the impact of hybridisation and introgression on genetic variation of these two species in selected European populations. For our study, we used 31 Viola populations from four European countries, which were analysed using AFLP and sequencing of a variable plastid intergenic spacer, trnH-psbA. Our analysis revealed that V. reichenbachiana exhibited larger haplotype diversity, having three species-specific haplotypes versus one in V. riviniana. The relationships among haplotypes suggest transfer of common haplotypes into V. riviniana from both V. reichenbachiana and hypothetically the other, now extinct, parental species. AFLP analysis showed low overall genetic diversity of both species, with V. riviniana showing higher among-population diversity. None of the morphologically designated hybrid populations had additive AFLP polymorphisms that would have indicated recent hybridisation. Also, kinship coefficients between both species did not indicate gene flow. V. riviniana showed significant population subdivision and significant isolation by distance, in contrast to V. reichenbachiana. The results indicate lack of gene flow between species, high influence of selfing on genetic variability, as well as probably only localised introgression toward V. riviniana.

An interesting abstract for fans of Violets. 
Peter Leonard
Rampton, Cambridgeshire.
7th April 2019 

Wednesday, 3 April 2019

Reichardia ligulata on Tenerife

Reichardia ligulata? on Tenerife.                                                                        11th March 2019

On a short visit to Tenerife we stayed in Santiago Del Teide, in the Teno region, North West Tenerife.
One trip was to drive out to the Punta de Teno, the lighthouse at the very north west tip of the island via the dramatic road that is cut into the northern cliffs.

The area has a short chapter in the 'Natural History of Tenerife by Philip and Myrtle Ashmore' ,  and contains many endemic species with areas of Euphorbia etc.  ( pages 68 - 71).

We drove out to the end of the road and walked out to the lighthouse.

Looking back towards the mainland from the lighthouse at Punta Del Teno.

Far from a green and pleasant land, the area round the lighthouse is almost devoid of plants.

A yellow composite beside the road.
 With only about three plants to look at, I though I better take some photos of a yellow composite growing right beside the road.

First thing to say was I did not recognise it, another strange plant growing in a very strange place.

Crinkled and spiky leaves growing in a clump with flower stems supporting two or three flowers.

Close up of leaf, thick fleshy with spikes.
Thickened stem before the bulb shaped flower head.  Tough looking bracts stick out but no hairs are present, only a few black bumps a bit like the cockscomb on Cat's-ear (but they are hairs whereas these are just bumps).
(There may have been a few hairs on the inside of the bracts at the tip, see open flowers photo below.)

A more open flower head shows the yellow petals with slight red in the tips.

Open flower

Top view of flower.

Achenes with white simple hairs.

The 'Natural History of Tenerife' does not claim to be a field guide to the plants of Tenerife however it does have many photos of plants to be found in various habitats. One that seemed to fit was found on page 73 with a very short text, 'Another distinctive plant is the composite Reichardia ligulata with crinkled , fleshy, thorny leaves and all-yellow flowers'

This would seem to fit the plant photographed here although the description lacks the detail to be certain.

Google images for Richardia lingulata have several photographs that correspond well to the above plant, however they also have some photos, that despite being labelled as Reichardia ligulata do not resemble the plants photographed here.  

Unlike the the Tree Sonchus, the Reichardia family does not  appear to have multiple species on Tenerife.  Reichardia ligulata is present on all the Canary Island.

Three plants were present at the lighthouse site beside the approach road.

Peter Leonard
Rampton, Cambridgeshire
2nd April 2019

Saturday, 30 March 2019

Sonchus acculis on Tenerife

Sonchus acculis? , another massive 'dandelion' on Tenerife.

On our walk west of Erjos, the first 'Yellow Composite' seen beside the track was a massive rosette of leaves supporting a single flowering stem that splits to support some large yellow flowers.

 Erjos, Teno Region, Tenerife. 
By British standards this is an extreme plant with its rosette typically a meter across. It is still a 'dandelion' in terms of its flower but still quite a shock to see.

Calling it Sonchus acculis is based on a brief description in the 'Natural History of Tenerife' but without a full description being available there is room for considerable error, especially as Tenerife has apparently 700 endemic plant species.

'Dandelion' type Flower

 Apart from the large size the other strange feature of the flower buds is that they are covered in a thick layer of white hairs. This is especially thick on the un-opened buds where you almost think they are covered in some form of fungal growth.

Some flowers have less of these white fluffy hairs so you can see the bracts, or they may just be wearing off.
Single plant showing leaf rosette.

Leaf with spiky margin.
Large size apparent in this photo.

We continued our walk past the transmission towers and into the laurel forrest where we found more of these plants. Sometime the rosette is not on the ground but supported on a brown stalk which old leaves hanging down.

Rosette supported on woody stalk.
 On the boundary between the laurel forrest and the more open hillside near the transmission towers is a good place to find Bolle's Pigeon.

Detail showing achene.

Peter Leonard, Rampton, 30th March 2019

Tuesday, 26 March 2019

Sonchus canariensis in Tenerife

Sonchus canariensis or is it?.

Example Yellow Composite plants on visit to Tenerife. 10th March- 15th March 2019

 Tenerife has been isolated from Africa and Europe for 12 million years, so plants have developed many endemic species through geographical separation and  adaptation to an extreme environment.

The yellow composites ( Dandelion type) have some really extreme examples that showed up on our first walk from Erjos in the north western region of Teno. The one photographed here was Sonchus canariensis, sometimes called the Tree Dandelion.

Sonchus canariensis?.

To see a 'dandelion' six feet high was a bit of a shock as I had no idea a plant like this existed. Using the 'Natural History of Tenerife by Philip & Myrtle Ashmole' I managed to identify it as Sonchus canariensis.    A heavily branched shrub it can reach 3m high, almost a small tree. It was quite common around the Teno region and common around our base in Santiago Del Teide.

Thin Leaf shape, more air than leaf.
Typical leaf shown above but some leaves have a thicker shape, see lower leaves in photo below.
Typical Plant with thicker leaves

Very pale yellow-green stem and bracts becoming darker towards tips.

Some variation with more rounded outer bracts, darker type.
Flowers showed some variation in shape of outer bracts and density of inner bracts. Second example has white fluff around the bracts and there are more rounded in shape compared with the first photos.
Quite a difference between these two photos that I can't explain. The number of inner bracts seems much higher in the second type. This looks like more than variation?

Buds before flower opens, similar to type above, darker type.

Post flower , pale type

Stems branch many time to support flowers ( pale type)

Another possible difference is that the pale bracts type seemed to have thiner leaves whereas the darker type bract plants had thicker leaves.

Flower, top view
Receptacle with achenes.
Conclusion.  This is quite an amazing plant(s). We were lucky that it was in full flower on our visit but I now wish I had noticed the differences and investigated more at the time.  Although the 'Natural History of Tenerife' is an excellent book as it says in its preface it is not a systematic treatment of the plants which will have to wait for another book. I could not find a guide to the plants of Tenerife and have relied on the internet, which has its limitations. I had assumed all these photos are of Sonchus canariensis. The other possibility is that these tree Sonchus have spilt into several species and one name that has come up on the internet is Sonchus arboreus which is not mentioned in the 'Natural History of Tenerife' at all . Sonchus arboreus would appear to be present on Tenerife but I could not find detailed descriptions that would help with these species.

The lack of a good field guide is a major limiting factor when looking at flowers on Tenerife especially when there are so many endemic species (700 ). Photos of both species are present on Google but how reliable they are is hard to say, except they look very similar. None have the detail to really help. Some where there must be detailed descriptions of Sonchus but I have not found it.

The plants photographed were beside the path near the pools just south west of Erjos, so shared the same habitat.
Any comments welcome.

Peter Leonard
26th March 2019

Post Script.
The problem to identify Woody Sonchus on the Canary Islands has just got a lot more complex.
I found that some research based on plants grown in a greenhouse in California from seeds obtained in Macaronesia ( Azores, Maderia, Canaries and Cape Verdes) which lists rather more species than the two mentioned above. No ID information is included in the paper and the writers may never have been to to the Canaries. It would appear that the evolution of these Woody Sonchus species has had a lot of scientific attention with papers in Linnean Soc Vol 76:249-285 in 1978 that I can't access.
The paper below contains this list of species, all but two are endemic to the Canaries.
It is mainly about evolution of different leaf shapes in response to habitats.

The California paper can be found at : research

Correlated Evolution of Leaf Shape and Physiology in the Woody Sonchus Alliance(Asteraceae: Sonchinae) in Macaronesia

Article (PDF Available)inInternational Journal of Plant Sciences 170(1) · January 2009 with 100 Reads
DOI: 10.1086/593044

All but two of these species are endemic to the Canaries.

Saturday, 16 February 2019

Hawksbeards ( Crepis capillaris, Crepis vesicaria , Crepis biennis)

Hawksbeards.                                                                                      Yellow Composites ID article 

The Hawksbeards ( Crepis) species group are difficult to identify.
Crepis capillaris    Smooth Hawksbeard
Crepis vesicaria    Beaked Hawksbeard
Crepis biennis        Rough Hawksbeard

Separating Beaked from Rough Hawksbeard can prove a challenge.
 Fortunately they do not hybridise so we are left with just variation to contend with.  They also look similar to other yellow composites, especially the Hawkweed group.  The Crepis group has two rows of involucre bracts, the outer being spread out, whereas the Hawkweeds tend to have all the bracts held tight and in more rows.

Hawkweed ( Burren, Ireland)
Hawkweed ( Royston, UK)
Crepis vesicaria ( Cambridge)
Crepis capillaris ( Cambridge)

The similar feature with Crepis and Hieracium ( Hawkweed) at least in terms of flowers heads is:-
Dark (sometimes glandular) hairs ( simple , no splits)
White hairs (sometimes glandular) ( simple no splits)
Cobwebby white hairs ( arachnoid hairs).
Differences are outer bracts spreading and white pappus hairs in Crepis. Achenes are very different.
Hawkweeds are an even more difficult group than Crepis and are only mentioned in passing as they need to be excluded first.

1)  Crepis distribution.

The three species covered here are wide spread in the UK, Smooth Hawksbeard ( Crepis capillaris) is very common throughout Britain and Ireland, Beaked Hawksbeard ( Crepis vesicaria ) is common in England and Wales but less so in the North but present in Ireland whereas Rough Hawksbeard (Crepis biennis)has a much more patchy distribution mainly in England and some in Ireland.
There are two other species with more northern distributions not covered here  Crepis paludosa, Marsh Hawksbeard and Crepis mollie, Northern Hawksbeard which are well covered in the excellent blog which also includes comparison with Hawkweed :-   Article on Northern Hawk's-beard (left side menu).

2)  Structure.

The basic structure is one or more major stems splitting into branches with numerous flowering heads and with leaves at the base and at branching points. Size can be highly variable especially Crepis capillaris which can have robust large plants up to one meter high or can be tiny lawn plants just a few cm high. Crepis capillaris is generally a more slender plant.
Crepis capilllaris ( Rampton)
Crepis vesicaria ( Rampton)

Crepis biennis ( Cottenham)
3)  Achenes.
The really easy way to separate these three species is to look at their achenes ( seeds) which have very different shapes.

Crepis capillaris
Crepis capillaris. (Smooth Hawksbeard)

Crepis capillaris

Crepis capillaris (9 July 16 Grantchester)
The achenes are typically short at about 2mm long plus the pappus hairs which are clean white and simple hairs ( no side secondary hairs).  The achenes are strongly ribbed ( about 10 ) with pale edges and tapper at each end. They may be straight or curved. The short length is distinctive although this does not show in these photos as the scale is hard to judge with variation in the size of the flower head.

Crepis vesicaria. ( Beaked Hawksbeard)

Crepis vesicaria ( Longstanton, Cambs)

Crepis vesicaria ( Cottenham, Cambs)
The beaked achene gives this plant its common name.  The achene is typically 7-8mm long plus the pappus hairs ( again simple bright white). They are fully beaked with the achene tapering down for about half its length. The achenes are ribbed (10) with pale edges and have tiny teeth.  The receptacle has the pits surrounded by short hairs.

Close up of receptacle and beaked achene.

Crepis biennis ( Rough Hawksbeard)

C. biennis (Rampton 18th June 17)

C. biennis (Rampton Guided Bus Way  4th Jul 17 )
The achenes are similar to those of C. capillaris but at least 4mm long, typically 6mm whereas C.capillaries are typically 2mm long ( 1.5 to 2.5) . C biennis achenes have ribs which from these photos seem much less regular with some larger than others. Typically 13 ribs but up to 18.

This is fine except that very often you find flowering plants that have not reached the stage where the achenes have developed.  One feature is to see if the shape of the achenes is apparent when the flower is developing. Time to look at the flowers.

4)  Flowers. Top View

4a) Crepis capillaris. Smooth Hawksbeard

C. capillaris  (22 Jul 18 )  Note Yellow Stigma

C capillaris have quite small flowers, similar to the flowers of Nipplewort, being 8-15mm across ( robust form up to 20mm)  and this is a important ID feature.  C. vesicaria can have similar sized flowers and C. biennis have much larger flowers heads and often appear more ragged compared to the neater capillaris. Outer banding can be reddish in some plants.

C. capillaris 14Jul18  
Note stigma are are greenish. Style is yellow.

4b)  Crepis vesicaria. Beaked Hawksbeard

C. vesicaria ( 2 May 15)  Greenish Yellow style and stigma.
C. vesicaria ( 10 Jun 18,  Royston) stigma greenish.

The flowers are 15-40mm across often the outer petals having reddish ( or white) banding on outer face. Tip can show red. May have more petals than C capillaris, but generally more ragged than capillaries.

C vesicaria (13May18 Soham)
Typical array of flowering heads with bright yellow petals and some red banding, plus ragged appearance.

4c)  Crepis biennis   Rough Hawksbeard.

C. biennis ( 9Jun18)  Note Yellow style and sigma

C. biennis (9Jun18 Longstanton, Cambs)

The second flower is more mature but still shows completely yellow stigma and style.  The petals are completely yellow with no reddish banding. The two features are worth checking as they seem to be reliable. Flower across  30-45mm. much bigger than C. vesicaria.

C biennis ( 2Jun18 Great Eversden, Cambs.)

5)   Flowers Side View showing involucral bracts.

5a) C. capillaris. Smooth Hawksbeard

C. capillaris ( 22Oct15)

Typical flower showing the outer bracts spreading and curving back into touching the inner bracts.
Occasionally the outer bracts stay close in ( adpressed), not spreading.The outer bracts are thin and are hairless except for slight a cobwebby ( arachnoid) hairs. The are about a third in length of the inner bracts which have short black hairs mainly on or close to the centre line plus the white cobwebby hairs.
Overall colour of the bracts is pale green with edges slightly paler again.

C capillaris (14Jul18)
Again a typical flower. Black hairs prominent.

C capillaris ( 30 Jun 16)

Note the best image but the only photo I have a of the robust form of C. vesicaria.  Structure conforms to the examples above. Note slight red banding on our petals.

5b)   C. vesicaria Beaked Hawksbeard.

C. vesicaria (10Jun18 Royston)
May have more petals than capillaris but basic structure the same with a few outer bracts curving out.
Red banding on outer petals. Cobwebby ( arachnoid ) white hairs present plus the black stout hairs and some longer white hairs with glandular tips.
The outer bracts are wider and stronger looking than C capellaris but very similar to C. biennis.
A marginal difference is the outer bracts have very pale white edging which is clear in this example.

Red banding prominent ( 12 Jun16)
C. vesicaria (2Jun16)

This example is chosen as the cobwebby hairs are prominent but it almost lacks the stout black hairs which are tiny and the long white hairs which are more typical. An example of variation.

Cut flower, late stage
Cut Flower, early stage
It is possible to see the shape of the achene before the flower develops in the pappus stage. The late stage photo clearly shows the beaked achenes forming but the early stage also shows the achenes thinning down just before the pappus hairs.  This is not always so clear cut as the achenes on the left are not showing this feature as well as the ones in the centre of the photo.

5c)  C. biennis Rough Hawksbeard.

C. biennis 31May14

Outer bracts are very robust and have a dark centre line in this particular plant. Cobwebby hairs as usual plus some stout black hairs.  Pale yellow petals without red banding.  The outer bracts tend to stick out rather than curve inwards and they also tend to a pale green rather than white.  

C. biennis 22May16
This example lacks the dark centre line on the outer bracts.  The outer bracts do not start at the same height on the stem. This is quite common in all three species. This plant also is showing the pale green edging to the outer bracts.  

C biennis 9Jun18
Achene shape is well developed at the post petal stage. No sign of beaking.

C biennis 25Jun18
Petals have faded but at this stage achene shape without beaking is apparent.  

The shape of the developing achenes are probably a more reliable feature than the appearance of the bracts or leaf shape or colour of the sap.

6) Leaf shape.

C capillaris.
C capillaris  Lower leaf shape with thin protrusions at right angles.

C. capliiaris (30Jun16) Basal leaves. Robust plant.
Basal leaf without 90Deg points
Lower leaves and basal leaves can vary in shape but often have the protrusions stick out a 90 degrees to the axis. Mid stem leaves have pointed lobes which is a distinctive feature of C. capillaries.

C. capillaris (9 Jun18) 
A common feature in all three species is that the stem can be green or can have bright red lines running up. Some populations have about a 50/50 split with half the plants having completely green stems and the other half having the red lined stems. 

C vesicaria

C vesicaria Mid stem leaf (10Jun18)

C vesicaria 13May18 (Soham) 

Leaf shape is complex and very variable. It must be very hard to describe some of the complex shapes using words.   I am not convinced leaf shape is much help when separating C vesicaria from C biennis. The photo below shows how spiky they can be, mid stem example.
Crepis vesiciria , Bottisham 4th June 19

C biennis.
Lower leaves

C biennis Lower Leaf

Just when you might think a pattern or feature is apparent, a leaf will come up that breaks the rule. The only conclusion I have come to is Crepis biennis can have the most variable complex leaf shape
possible and that may be a feature in itself. Using leaf shape to distinguish between C vesicaria and C biennis is beyond me.

7) Sap Colour

The sap colour of Crepis vesicaria is noted as bluish-white and Crepis biennis as yellowish-white in Harrap's Wild Flowers.  

C vesicaria (3Jun18)

C biennis (21Jun16)
In practice the difference in sap colour may not be as pronounced as in the photos above but to date seems to be a reliable feature. 

8) Conclusion

The above photos give the basic difference between the three species.  This blog does not fully cover the variation and problems with plants that have been cut down and re-grown.  Achene shape is the gold standard feature even if looked for in flowers that are still in bloom.
C biennis seems to never have red banding that is often present in C vesicaria.    C vesicaria often flowers about two-three weeks before C biennis.
Stem leaves with pointed lobes at the base is a good feature for Crepis capillaris together with the lower leaf protrusions at 90degrees. As usual with difficult species as many features as possible need to be considered as plants are variable. A table follows as a trial key ID feature test. This will be used to see if these features always stack up or are not reliable in 2019. 

An example of extreme variation, the last photo below is of a flower taken in Baltimore, County Cork which is an example of C capillaris which had been cut down and regrown. Definitely one for the expert who confirmed its identification to me, based on several photos showing the leaves with the 90 degree protrusions. A very strange plant. 

9May2015(Baltimore, Co Cork)
Summary. Features to be tested in the spring and summer 2019 to determine how useful they really are.
Any comments and corrections always welcome. Crepis vesicaria flower during May in Cambridgeshire, whereas Crepis biennis starts flowering at the very end of May.

Some comments that the flower size of biennis is pretty conclusive enabling ID to be made out of the car window and this is probably true. Hight is often a factor where biennis can be much taller but this is not always true. Sap colour may not be 100% as some biennis have quite white sap which may only just show the yellow tinge after about a minute.

A comparison of flower size follows. In this case capillaries is not so different to the flower of vesicaria , but biennis is about 38mm across.

Peter Leonard
Rampton, Cambridgeshire
16 Feb 2019 updated 5th June 2019

White banding on underside of petals on C. vesicaria 19th May 2019 

Spot the biennis in the sea of vesicaria, Cottenham 31st May 2019