Saturday, 25 April 2026

Veronica cymbalaria Pale Speedwell

Veronica cymbalaria Pale Speedwell

Complications with the identification of a rare mediterranean alien in Britain.



Veronica cymbalaria, Crete, April 2026  


Veronica cymbalaria, Faversham, Kent, 10 Feb 2026.

Veronica cymbalaria has occurred in five sites in Britain and Ireland. First recorded in 1985 by B.M.Sturdy near Penzance where it persists, at least to 2023. Recorded near Glasgow in 1999 and also in Belfast. More recently found on a petrol forecourt by Paul Stanley in Southampton in March 2023.

It also was found in Faversham, Kent on 5th Feb 2021 by F. R. Gomes. I assume all these records conform to the standard form with hairy capsules.

Veronica cymbaleria has a Mediterranean distribution with records north to Germany and east to Iran.

The key features of cymbaleria are the pure white flowers (6-10mm Dia.) and the leaf shape with 5-9 lobes and the terminal lobe being wider, but not as pronounced as in V. hederifolia.  It is stated in nearly all the literature that another key feature is the hairy capsule, compared to the hairless capsule of V. hederifolia

V. cymbalaria, Faversham, 10Feb 2026. Capsule and sepals.

V. cymbalaria, Faversham, 10Feb 2026. 

Veronica hederifolia. note hairless capsule and pointed hairy sepals.

The identification features seemed straight forward until a visit to Crete in April 26 where some plants had hairless capsules. The majority of V. cymbalaria plants in Crete had the expected hairy capsules. The Crete plants did have glandular stem hairs, which was not seen on the Faversham plants.
 In two sites in Crete, some plants had completely hairless capsules and sepals combined with glandular hairs on the upper stems. They grew with the hairy capsule plants and had the same flower size and general appearance.

The question was whether these hairless capsule plants are a different species or just a variation on V. cymbalaria?.   


V. cymbalaria glabrous (hairless) sepals and capsule. 


V. cymbalaria at Late Minoan Cemetery at Armani, Crete. April 26

Hairy version of V. cymbalaria , Crete, April (growing with hairless capsule version). Note the glandular hairs on upper stem, sepals and capsule.


Research on the web indicates that V. cymbalaria is polymorphic and can have versions that have hairless capsules. A very similar species with hairless capsules is described as V. panormitana but that has smaller flowers.

From Web search...

The term "polymorphic" in relation to Veronica cymbalaria (Pale Speedwell) refers to its complex genetic and evolutionary history, characterized by multiple chromosome counts (polyploidy) and varied physical forms


Polyploidy and Genetic Diversity

  • Multiple Origins: Research shows that tetraploid (pastedGraphic.png2n=4x) and hexaploid (pastedGraphic.png2n=6x) versions of this species evolved independently several times in the Mediterranean.
  • Complex Evolution: It is part of a "polyploid complex," meaning it has several sets of chromosomes from different parent lineages, leading to high genetic variation.
  • Genetic Markers: Scientists use polymorphic SSR markers (microsatellites) to study gene flow and how these different genetic versions are related.

Morphological Characteristics

  • Variable Appearance: While generally a sprawling annual with white flowers (6–12 mm), it can range from being almost hairless to very hairy (glandular hairs).
  • Leaf Shape: Its leaves are round or "cymbal-like," typically having 5 to 9 lobes, which distinguishes it from similar species like Veronica hederifolia.

Two papers on the subject are :-

1) From 2022. An overview of Veronica in general but based on work by Manfred A Fisher who was the expert on this family.  Includes a photo comparison of V. cymbalaria and V. panormitana showing the smaller flowers of the latter. Early genetic work was indicating that V. cymbalaria in its polyploid forms are derived from V. panormitana and V. trichadena.  

What is a species in Veronica? Reflections ...Zobodathttps://www.zobodat.at › NEIL_13-14_0305-0323 

2) From 2007. A very complex paper:-  Amplified fragment polymorphisms and sequence data in the phylogenetic analysis of polypoids, Multiple origins of Veronica Cymbalaria

 Not much help except to confirm that the V. cymbalaria complex is variable in features and has a very complex history involving V. panormitana and V. trichadena with diploid, tetraploid and hexaploid forms.

For the practical botanist one feature of interest was that the stomata size from lower bracts was measured and found to be:-

Diploid   25.8 +/- 2.4 micrometers

tetraploid  35.5+/- 2.7 micrometers

Hexaploid. 40.7 +/- 3.5 micrometers.

"In a conservative approach plants with stomata 32.5-37 micrometer were designated as tetraploid.

Those with stomata between 42 and 46 micrometers long were designated as hexaploid. Environmental factors could cause quite a large variation in stomata size." I assume a reasonably large sampler size would need to be taken for this to be useful. Pity I did not take a sample of a leaf.

https://doi.org/10.1111/j.1469-8137.2007.02172.xopen_in_new

Conclusion.

V. cymbalaria is a complex with various sub-species listed but I failed to find detailed descriptions of the sub-species and I guess that the hairless capsule plants are just an example of variation rather than a different species. Hairs are a defence against insects, especially those with glandular tips but use energy to create. The majority of plants seen on Crete were of the standard type with hairy capsules and sepals, so it might be concluded that having hairs is a better option in evolutionary terms. Alternatively the plants without hairs might prove more successful in time and that is an example of the fundamental driver of survival.    

Most of the literature describing Veronica cymbalaria does not cover the variation that this species can show. It is so rare in the British Isles that most British floras do not cover the species at all. How plants of this species occurred here, in such a random widespread distribution is unknown but they have and will no doubt, occur in the future.   It is possible that future examples may conform to the glabrous version that I saw in Crete. Most of the literature does not cover the extent of variation and this includes the following article which has a table showing differences between related species in the group. 

Finally an interesting and comprehensive report about finding V. cymbalaria in New Zealand and making sure it was indeed that species.

Veronica cymbalaria, a new record for New ZealandNew Zealand Plant Conservation Networkhttps://bts.nzpcn.org.nz › site › assets › files › ak_...


Peter Leonard

Cottenham, Cambridgeshire

April 2026

i

Sunday, 22 March 2026

Veronica agrestis and Veronica polita

Veronica agrestis ( Green Field Speedwell) and Veronica polita ( Grey Field Speedwell).

Although the main distinguishing feature between these two similar species is the type of hair on the seed capsule, in practice this is far less clear cut that the current literature implies. 

Several identification articles have been published recently covering Speedwells from the recent Beginner's Corner paper by Mike Crewe in BSBI News Winter 2025 158, page 21, and

  'A pictorial guide to some of the more common Speedwells of the British Isles' by Moira O'Donnell in the Wild Flower Magazine Autumn 2021. 

These articles and many identification guides like the revised version of The Wild Flower Key by Francis Rose, Harrap's Wild Flowers, and the new British & Irish Wildflowers and Plants, A pocket Guide, all state that Veronica agrestis has capsules with long glandular hairs ONLY.

Maybe this is true in some places but it is certainly not correct in East Anglia. This was pointed out back in 2010 by Bob Leaney, BSBI News, April 2010, No 114.

Common problems with identification in the field – experience

with the Norfolk Flora Group

13. Veronica agrestis (Green Field- speedwell)/V. polita (Grey Field-speedwell) The only clear-cut vegetative field character here, according to Poland & Clement, would seem to be the longer petioles in A. polita (<4 mm, as opposed to <2 mm). I have looked at about twenty specimens in the field and NWH, and found that leaf shape and colour were often intermediate and unhelpful. Attempts to separate these two in the field usually resolve around the capsule hairs, but these need a ·20 lens and good light conditions to interpret, and usually there is a difference of opinion! When one gets a few capsules under the microscope at home, moreover, one often comes to a different conclusion! In my opinion, a much better field character is the shape of the sepals, where there is a very clear cut and invariable difference. The sepals of V. polita are always broadly ovate, with the distal edges straight and converging onto a sub-acute or acute tip. Those of V. agrestis, on the other hand, are narrowly elliptic-lanceo- late, with +/- parallel sides and the distal curving very gradually to a rounded tip (see illustration). In fresh material these sepal characters correlate absolutely with the capsule hairs, and they also correlate well with leaf colour and shape when these characters are clear cut one way or the other.

Recently Mike Wilcox has a useful article in BSBI News issue 153 April 2023 'Distinguishing Veronica agrestis from Veronica polita', which correctly states that Veronica agrestis can have mostly long glandular hairs, though a few eglandular hairs can occur. Mike Wilcox also introduces a new feature which is that the stigma is squeezed between the two capsule lobes whereas Veronica polita has a longer stigma which is not held so tightly due to a slight difference in capsule shape.

My conclusion is that recent literature, except Bob Leaney and Mike Wilcox, has often simplified the hair characteristics, as if you go back to the excellent Clapham, Putin and Warburg 'Flora of the British Isles' 1962 it states V. agrestis capsule with long glandular hairs, often with rather shorter glandless ones'.

I have been taking photos of speedwells in an attempt to produce a photo guide and have found that all features that differentiate these two species are subject to qualifications. An example being the sepal shape that Bob Leaney was keen on. This can only be relied on when the capsule is fully developed as the broad sepals of V. polita get wider during the development of the capsule. Looking at the sepals at the flowering stage does not help as they may be as narrow as those in V. agrestis.


V. polita flower showing narrow sepals. 25th Feb 26
            Sepals at flower stage are both narrow and have not developed their final useful shape. Sepals may enlarge to protect the seed capsule as the seeds develop. The capsule hairs are another defensive feature to protect the seeds that are inside the capsule.
 
V. polita at capsule stage showing both types of hair and ovate sepal.

The above photo shows that the fully developed sepal shape is wider and ovate, in that it has the widest point below the middle and has an acute tip. However there is variation as shown by the left sepal which is not as wide. The stigma still looks quite fresh so this sepal may develop further. 

V. agrestis sepals (despite having some slight lobing) are oblong/linear with parallel sides and rounded tip. Overall a more narrow shape.

V. agrestis showing narrow oblong/linear sepals shape. It appears to have a unusually short stigma which looks fresh and not decaying yet. 17Jul 2022

Conclusion. The sepal shape is a good feature but only when the capsule is well developed.

How to identify between these two species and Common Field Speedwell ( V. persica).

1) Flowers. In many cases the first thing that stands out when looking at both V. agrestis and V. polita is that the flowers are much smaller than a typical V. persica Common Field Speedwell.  Flower colour can be variable in speedwells and paler to white examples of many species can occur. 

Flower colour is also a good guide as V. agrestis has pale flowers often very pale almost white, whereas V. polita often has really dark blue flowers, but can have paler flowers which makes some look intermediate. Occasionally speedwells have white flowers, so flower colour is a good guide but not conclusive. I have never seen a V. agrestis with dark blue flowers.

2) Capsule. Second step is to look at the capsule if you can find one. It is important to find a fully developed capsule as early or sterile ones do not show the shape differences which are useful.  

The capsules nearest the flower will be the most undeveloped so it is good to move down the stem and check several capsules. The most developed will have the stigma decayed back so that comparing stigma length at that stage has difficulties but works well for sepal shape. 

Capsule shape can vary as seen in V. persica. The capsule lobes are not spreading in both V. agrestis and V. polita, whereas the lobes of V. persica has spreading lobes. The next photos show that the spread in V. persica does vary.  A feature rarely photographed. The shape is quite distinct however except in sterile or undeveloped capsules which can cause confusion.

V. persica capsule with less than usual lobe spread. 4th Jun 2023  
V. persica capsule with limited lobe spread and starts to approach the capsule shape of V. polita, 16Apr25
Note the capsule even in this extreme case, is much wider than tall whereas V. polita/V. agrestis would be square in profile being about as tall as wide. 

V. persica with typical lobe spread. 22April 25

Note the very long thin stigma which is often bent over and is protruding well beyond the top glandular hairs. The capsule hairs are a mixture of long glandular hairs and short slightly curved eglandular hairs. Density of both type of hairs can vary considerably. Sepal shape is quite variable at capsule stage.

Capsule shape and hairs, V. agrestis.

V. agrestis 10Jun2025
Note the long glandular hairs and no shorter eglandular hairs and the narrow sepals have rounded tips.
This one fits the literature. Slightly deformed lobes are unusual.

V. agrestis 11Jun2025
Note narrow sepals with rounded tips and just a few short eglandular hairs on capsule.
 V. agrestis Capsule with more short eglandular hairs amongst  the longer glandular hairs. Cottenham, Cambs. 11Jun2025

V. agrestis, showing how tight the stigma is held between the two lobes. 16Jun2025

V. agrestis. an example of variation as the stigma is not held tightly between lobes. 9Feb26

This photo shows that although the overall shape of two parallel lobes is good, the tightness of the held stigma can vary, so although this is a useful feature and can be a good guide but should be considered with other features, before making a determination. I suppose we should not be surprised having seen the variation in the V. persica in photos above. In my experience the feature of a tightly held stigma works most of the time but occasionally fails, but that's botany. The identification of this particular plant was based on the narrow sepal shape with parallel sides and rounded tip, the capsule hairs being mainly long glandular with few eglandular and the stigma although fairly fresh ( white colour with brown tip) being quite short, protruding out less than the hairs.

Capsule shape and hairs, V. polita.

Typically a dense fuzz of short eglandular hairs outnumbers the long glandular hairs in V. polita. but beware variation as mentioned above by Bob Leaney.

V. polita 13May2025 with fresh stigma protruding well beyond hairs.

Capsule hairs are a mixture of longer glandular hairs and quite dense short eglandular hairs. Broad ovate shape to sepals and stigma not held tightly between lobes.

V. polita 13May2025
The stigma although starting to decay is still protruding well beyond the level of the longest hairs.
The sepal shape is broad, ovate and reasonably pointed at the apex. The capsule hairs are a mixture of long and short, about 50:50 in quantity. V. polita have been seen with lobed sepals which adds a bit more challenge.

V. polita  10Jun2025

The stigma has started to decay and turn brown but still remains long and protruding well beyond the hairs. Lots of short eglandular hairs.

Flowers.

V. polita, only three petals, just another example of variation.10Jul2023

V. polita, typical dark flowered example. 11Apr2023

V. agrestis. 10Aug2023


V. agrestis 17Jul2022

3) Other features.

Many books mention the difference in leaf colour, hence the English names Green and Grey however in practice there seems to be overlap and leaf colour seem more dependent on growing conditions. Occasionally V. polita seems to have thicker more fleshy leaves which are dull but again this is not consistent. There is some truth that the length vs width of V. agrestis leaves suggests that the longer leaves of V. agrestis vs 'the length similar to the width' for V. polita is a useful feature however the shape of leaves is quite variable. 

V. polita, leaf length similar to width.

V. agrestis Leaf shape longer than wide.

Stigma length. The problem with stigma length is that the stigma will decay back, going brown and becoming shorter sometimes quickly . Also there seems to be quite a variation in the length. When fresh, the length of  the stigma in V. agrestis may just reach beyond the top of the long glandular hairs but is often much shorter. In V. polita the stigma often reaches well beyond the top of the longest hairs.
Best to check several capsules and forget those which have decayed stigma. If you can find a stigma well beyond the hairs it is a V. polita. 

Stem hairs.  Upper stem hairs of both species are dense curved short hairs with a few long hairs, on lower stems the short hairs become less, leaving just long hairs equal to the width of the stem in length.
V. agrestis upper stems have dense short hairs in two bands with some longer hairs. V. polita has short hairs which are longer than the short hairs in V. agrestis and mixed in with longer hairs. Looks more untidy.
 I am not sure stem hairs will distinguish V. polita from V. agrestis, as a larger sample would need to be checked.


Veronica agrestis, upper stem hairs tend to be very short and dense with occasional long hairs.
The dense short hairs are curved and are more dense in two broad lines down the stem. 

V. ploita, upper stem hairs, hairs slightly longer and more a mixture of long and short.

Conclusion.

The above is based on plants seen in Cambridgeshire and Kent only. Although many plants are not too difficult to separate, care should be taken to check all relevant features to make a determination.  

I order of importance I would suggest, Flower colour, capsule hairs, sepal shape but beware some variation like V. agrestis having pointed apex and then stigma length and tightness of stigma being held.

Leaves of V. agrestis are slightly longer but V. polita leaves are often longer than wide as well, so difficult to use as a feature. 

Leaf stalk, petiole is about 1.5X stem thickness in V. polita vs. about 1-2X in V. agrestis and is too variable to be useful.


Peter G. Leonard

March 2026

Cottenham. 

                          V. agrestis                                                  V. polita



V. agrestis. close up of capsule hairs showing a few shorter hairs.





Friday, 14 November 2025

Chickweed Willowherb, Epilobium alsinifolium

 Chickweed Willowherb, Epilobium alsinifolium.

I have been taking photos of Willowherbs this year and a trip up to Upper Teesdale in early August raised the possibility of seeing two northern species, Alpine Willowherb ( Epilobium anagallidifolium) and Chickweed Willowherb ( Epilobium alsinifolium). Both occur at high altitude and are given full page coverage in Margaret E. Bradshaw's book 'Teesdale's Special Flora', published in 2023. In addition both species have been added to the Second Edition of Harrap's Wild Flowers which has been extended in a very useful way and is the best field guide due to its 'Detail' information. 

Alpine Willowherb is very much at its southern limit at Teesdale and it is a very rare plant with few recent records. Chickweed Willowherb is more frequent and has wider altitudinal range and even occurs further south in Snowdonia.  

Anyway I set off to see both and was lucky to find the more frequent species.

6th August 2025. 

As I walked up the steep hillside I spotted a damp area highlighted by pale green moss in which were a lot of Willowherbs. Up to that point I had only seen Marsh Willowherb, which were easy to identify due to their narrow leaves, but these plants looked very different with very wide leaves.

Typical Willowherbs flowers at the tip of the long seed capsule.

The problem was then to confirm the identification which was not easy. Both have a club-shaped stigma. Both have leaves that are hairless. Stems sparsely hairy in 2 rows for both, plus a lot of overlapping features like fruits 2-4cm long in Alpine and 3-6cm in Chickweed.  Flowers variably glandular-hairy on base of flower and fruit for Chickweed vs. a few glandular hairs on base of flower and fruit for Alpine. Clearly not a lot to go on here in terms of distinguishing features. 


Without any previous experience of either species I checked the books mentioned above. The main difference as noted in Teesdale's Special Flora, is that Alpine has yellowish-green leaves, tapered at both ends, unlike Chickweed Willowherb which has bluish-green leaves and have a rounded base with a distinct stalk. The colour difference does not appear to be strong in the example photos in either book.

Alpine Willowherb has leaves 1-2.5cm long described as elliptical-lanceolate, tapered at both ends, entire or faintly and distantly sinuate-toothed. Gradually narrowed below into a short, stalk-like base.

Chickweed Willowherb has leaves 1.5-4cm long described as ovate to ovate-lanceolate, distantly sinuate-toothed, rounded at base, petiole short.

Since elliptical means widest in the middle and ovate means broadest towards the base it would seem that the photo above shows the correct leaf shape for Chickweed Willowherb. This is backed up by the clearly toothed margins.

Chickweed Willowherb leaf, 6th Aug 2025.

Flower , none were open that afternoon.


Some patent glandular hairs on calyx and capsule.

Mid stem showing curved non-glandular hairs although the '2 rows' are not that clear.

It would appear that patent glandular hairs are frequent on upper stems but lower down are replaced by curved non-glandular hairs with both types present on upper stems. Strangely although the literature says the leaves are hairless, some tiny glandular hairs were present on the leaf margin.

The site I visited had a previous record for both rare willowherbs but I only found Chickweed Willowherb on this visit. I think I was lucky to find one species as the damp stream bed was the only place where these were present. Marsh Willowherb ( Epilobium palustre) was common in the area with its narrow leaves.  

Marsh Willowherb ( Epilobium palustre) Narrow leaves with downturned margins.


Marsh Willowherb, with patent glandular blunt hairs plus curved tapered hairs. 6th Aug 2025

Always great to find a target species.

Peter Leonard, 

November 2025


Tuesday, 24 June 2025

Fen Violet? Viola stagnina

 Fen Violet ( Viola stagnina ) or a hybrid?.  

This was one species of Violet that I had never seen. The local population in Wicken Fen has not been seen for many years and it would appear to have gone from Woodwalton Fen. A trip to the Burren in May 2018 had failed to definitely find one, although a possible hybrid with Heath Dog Violet ( V. canina) was seen in a grike.

The Burren,  below Mullagh More. May 2018

That potential Fen Violet looked good in terms of flower colour, but didn't quite in other details.

Potential Fen Violet May 2018

Another chance to see Fen Violet  occurred in June 2025, when I was able to visit Mullagh More and its adjacent turloughs again.  An even better candidate was found, however it would seem that Fen Violet at this site has largely hybridised with the more common Heath Dog Violet. This hybrid is called Viola x ritschliana.  A search south west of the road near the start of the walk to Mullagh More in a turlough, which had previous records, produced zero violets, which was disappointing. Despite the dry weather there was still water in the turlough and the edges looked like suitable habitat.

It was during a lunch break that our luck changed and a small population of about six violets was found near the turlough below Mullagh More.  R 3107 9456

Flower Plant 1 ,  28th May 2025. 

The flowers of Fen Violet are supposedly flat but the backward upper petals on this example do not conform to that description.  The tinge of violet on the petals is perhaps slightly more than typical for Fen Violet?

Spur and sepal appendages. Plant 1. 

Fen Violet is supposed to have a short straight pale green spur, whereas V. canina typically has a trace of pale yellow. The hybrid apparently has slightly longer whitish spurs which may be decurved. This spur looks good for Fen Violet. The backward pointing sepal appendages are very big but so are those on V. canina. In fact I find that the big sepal appendages are a really good feature in V. canina when separating from other Dog Violets.  

Stipules. Plant 1.
About all I can say is, that the stipules are coarsely toothed, but so are V. canina and the hybrid. The Violet Handbook suggests that Fen Violet has hairy stipules and are up to 20mm long. The 2nd Ed. Vegetative Key to the British Flora says; Stipules to 8mm x 1 mm, usually less than half as long as the leaf stalk (petiole) but does not mention hairy.  Stipules can be useful but can vary so I don't think this photo is much help.  The literature is inconsistent regarding hairy.

Leaf Shape Plant 1.

 
Leaf Shape Plant 1.

Leaf shape, was as seen from the two photos above, a bit variable but within the 2 to 4 times as long as wide, needed for Fen Violet. The base shape also looks good. V. canina has leaves 1 to 1.6 times as long as wide. The hybrid 2 to 3 times. Our Plant 1, had leaves 3.75 as long as wide. The dimensions would support Fen Violet however descriptions of Fen Violet often refer to the leaves being very thin and pale green compared with V. canina. These leaves did not seem very thin compared with Heath Dog Violet, V. canina.

Final nail in the coffin.

Not far (2m) from Plant 1 was another group of violets.

This group seemed to fit with Heath Dog Violet with blue flowers and shorter leaves except note the pale flower to the bottom left.

Two colour flowers on same stem.

I think this photo demonstrates the classic problem with plant identification, beyond the normal problem with variation. A single plant with its genetic code, has on a single stem produced two very different flowers. The genetic code can be modified by the environment to change features know as Phenotypic Plasticity. However this plant has produced two different flowers on a single stem, so environmental conditions are the same. This is not Phenotypic Plasticity, something else is going on and I think this points to hybrids, having more variability across a single plant.  Hybrids can be fertile and features can lie anywhere between their parents. In this case, the hybrid contains features of both parents and which one wins out is anybody's guess. 

This phenomenon is common in Roses. Wild roses are all derived from hybrids thanks to reticulate evolution* and often 'species' that have been stable, have consistent features, whereas if you find a rose bush with different features on different stems it is often a more recent hybrid. This might be chimerism, a term I was not familiar with in plants. It would appear that chimera are not fully understood and quite what would explain these two different flowers on the same stem remains a puzzle.

"In plant biology, chimera is often used to denote a specific case of visible variegation called Genetic mosaicism, which is a phenomena where cells of different genetic load are present within the tissue of one plant. "


Conclusion.

The fact that all the violets were in a small group with different coloured flowers would point to all of them being hybrids. To claim a Fen Violet I think I would have to find a population of consistent plants with very pale flowers and thin leaves. It would appear that the Fen Violets around Mullagh More have been hybridised out by the V. canina and another turlough in the Burren might be a better place to search. 

Plant 2. Pale flower on stem with blue flower.

Plant 2. Blue flower on stem with pale flower.

Life is never simple.

Peter Leonard 24th June 2025

Ref BSBI Handbook No 17 Violas of Britain and Ireland. 2017 by Michael Porter and Micheal Foley.


* Reticulate evolution, also known as network evolution, describes evolutionary processes where lineages merge and exchange genetic material, creating a network-like pattern of relationships rather than a simple tree structureThis contrasts with traditional evolutionary trees, which depict a branching pattern from common ancestors. Reticulation can occur through various mechanisms, including horizontal gene transfer, hybridization, and symbiogenesis. 

A paper on Chimerism in plants can be found :-

Plant chimeras: The good, the bad, and the ‘Bizzaria’

https://doi.org/10.1016/j.ydbio.2016.07.003