Sunday, 31 May 2020

Christmas Tree in May?

Identification of 'Christmas' Tree in May.


Lockdown Project. What is the conifer planted by the Rampton village hall?

I have never really got to grips with conifers, just one of those 'never quite got round to' tasks. I have quite a few tree books but they tend to jump straight into species.  With so many species and cultivars planted some knowledge of the genus groups would be useful.

The tree in question had no cones visible, it is not an old tree and in many ways unremarkable.

Checking through the books, I found 'Know Your Conifers',  Forestry Commission Booklet No 15  Price 6s 0d.   1970.   This had some good advice based on looking at the leaves. There is a warning to avoid upright leading shots or juvenile foliage.  'Go for the side branches' sounded good as some were within reach.
Leaves from tip of side branch of the Rampton tree.
Fist trick is that you can see the individual leaves or should I call them needles?.   They are not all tight to the stem so we can exclude a whole group of difficult conifers like Leylandii and Lawson Cypress.  Example photo below.

Leaves tight to stem. Flattish foliage.
Flattish tight leaves are probably from the genus Chamaecyparis which includes Lawsons Cypress or the genus Thuja which includes Western Red Cedar. We can exclude those.

Pines of the genus Pinus have  needles grouped in two's, three's or fives's so we can exclude those as well as we have single needles on the Rampton tree. The hemlock or Thuga genus  have needles that vary in length which the tree in question also does not have. I know it's not a Yew or a Juniper.

Juniper.
The next trick is to see how the individual needle is attached to the stem as that is a key identification feature. The needles are attached with a short brown peg.

Needles attached by a short brown 'peg'.

From the 'Know Your Conifers' booklet.

So now I know I am dealing with a spruce from the genus Picea because the needles are attached with a peg.

What kind of Spruce?

The "Know your Conifers' book covers two species of spruce, Norway and Sitka because back in 1970 that is what they grew commercially.

Actually there are quite a lot of spruces. Most are exotic, planted in gardens and arboretums.
The most common Spruce is Norway Spruce Picea abies and that is 'readily told apart from others by its soft mid-green needles, which are pointed but not sharply so'.

The Sitka Spruce Picea sitchensis has bluish or slate-grey tinted needles which end in a sharp point.
A short video from Jim Waterson picks out key features of Norway Spruce:-
https://www.youtube.com/watch?v=d2naxGZKOgY&list=PLRKWnZs4l1bBDFiFRME9zuvHYyZnCJ1Xm&index=6

The key features being classic green top and bottom of the needles which are of even length, and are distributed round the stem to give bottle brush like effect. Texture not harsh to the touch.

All this seems to fit with the tree beside the village hall. Norway Spruce used to be the most common Christmas tree but has been superseded by the Nordmann Fir.

The double check. See what a Norway Spruce looks like at Lynford Arboretum.

Norway Spruce Picea abies trunk

Picea abies needles attached by pegs.
This looks just like the village hall tree. The needles are green looking from the top and from the bottom. This is because the lines of white stomata are the same on all four faces of the needle. The stomata are in two or more usually three rows, of evenly spaced white dots. The brown stem has an interesting pattern and have almost no hairs. No hairs is a identification feature to separate different species of spruce.

Picea abies new growth showing the lines of stomata.
The needle tips can be seen to be quite pointed and the pegs are still green on new shoots.



 Needle attachment in other conifers, a few examples follow.

1) Silver Firs, genus Abies have needles attached by little green suckers.

Example, Grecian Fir Abies cephalonica.

Abies cephaloncia, needle attachment.

2) Douglas Fir Pseudotsuga menziesii.  Foliage most like the silver Firs but suckers are tiny and only evident when the needle is pulled off.

Pseudotsuga menziesii, needle attachment.

3) Western Hemlock Tsuga heterophylla.  The leaves are different lengths and do not have the same shape being flatter. The needles have thin bases that run parallel to the stem.

Tsuga heterophylla, 

Conclusion.

Little brown pegs mean Spruce,  Genus Picea. The tree outside the village hall is a Norway Spruce.
I have learnt just a little about conifers, so a start has been made.

Final shot another Spruce species to show pegs.


Serbian Spruce Picea omorika with pegs and hairy stems.

The End

Peter Leonard
24th May 2020



Wednesday, 13 May 2020

Herb Robert (Geranium robertianum) and Little Robin (Geranium purpureum)

Herb Robert (Geranium robertianum) and Little Robin (Geranium purpureum)

My Geranium ID Key Blog of last August highlighted the main differences between these two similar species; i.e. the smaller flowers of Little Robin and its yellow anthers. The blog did lack detail on the hairs that Little Robin displays. Here are a few additional photos to show Little Robin against the much more common Herb Robert.
Herb Robert left and Little Robin right, showing the size difference in the flower. 11th May 2020, Cambridge.
White petal lines more prominent in Herb Robert.

Little Robin showing the yellow anthers, Cambridge
Herb Robert showing orange anthers 28th June 2019 Cork

Herb Robert with dark purple anthers 17 June 2019
Herb Robert normally has dark purple anthers but can have orange anthers.
The pollen of both species is yellow so when comparing the anther colour pick a flower that has anthers which have not opened to avoid confusion.


Little Robin, sepal hairs 11th May 2020. Cambridge
Neglecting the stray hairs picked up from a nearby composite, the Little Robin has sepal hairs which are different lengths and have red glandular tips. These are similar to the hairs on the upper flower stem.

Herb Robert 28th June 2019, Cork showing the very long sepal hairs.
Herb Robert sepal hairs, 11th May 2020, Rampton
Herb Robert also has tiny red glandular tips to the sepal and flower stem hairs. The length is much longer for many of the hairs compared with Little Robin. The sepal hairs are longer than the flower stem hairs but the flower stem hairs also have some long hairs. Some non glandular hairs are also present on the flower stems and the main stems have curved simple hairs pointing downwards.

Little Robin, flower stem hairs similar to sepals but less dense. Ignore the stray composite hairs.

In summary Little Robin has sepal hairs that look quite normal whereas Herb Robert seem excessive.
This is a generalisation and sepal and flower stem hairs will vary depending on the population. The amount of hairs is a variable feature, however this is an interesting difference.

Leaves.

Little Robin has pale green leaves that look smooth and hairless to the naked eye. A close look shows they do have some hairs. Herb Robert can have slightly darker green leaves and again it is easy to miss the sparse hairs. Leaf shape is similar between these species. Stems are often red in both species. It is usually regarded as impossible to identify these two species apart, using vegetative features.

Pale green leaf of Little Robin, with some sparse hairs just visible. 11th May 2020 Cambridge
Some leaves have a thiner shape.

Little Robin leaf, 11th may 2020 Cambridge.

Stem Hairs

Stem hairs are mainly short downward curved hairs without glandular tips. G. purpureum
Stem hairs are mainly the short curved hairs but occasional simple long hairs are present or some stems may be hairless.


Hybrids between these two species have been found and the situation in Europe is apparently more difficult due to variation.  Herb Robert has chromosome count 2n=64, Little Robin 2n=32.
Some suggest that Little Robin is a parent of Herb Robert. Cross fertilisation experiments have been done but the situation in the wild is not clear. It is suggested that some hybrids have no flowers but I can't see how you would prove that this is a hybrid. Some plants have been found with intermediate features. It is not known if any recent research has been done on these two species to confirm their relationship.

Little Robin records from Cambridgeshire have been from sites associated with the railways. Recent expansion of Little Robin may be related to winters with less hard frosts.

Peter Leonard
Rampton, Cambridgeshire.
11th May 2020


All comments welcome.












Saturday, 2 May 2020

Erophila ( Common Whitlowgrass)

Erophila (Common Whitlowgrass) and its close relatives.

The fullest and most useful account of Erophila is given in the BSBI Plant Crib ( T.C.G. Rich and A.C. Jermy) by S.A. Filfilan and T.T. Elkington, available on the BSBI website. The second source is the 'Crucifers of Great Britain and Ireland' by Tim Rich BSBI Handbook no 6.



In summary, it would appear to be, that within the UK Erophila is split into three 'species' by chromosome number.

E. majuscula        ( Hairy Whitlowgrass)        Chromosomes 2n=14  (Diploid)
E. verna               ( Common Whitlowgrass)   Chromosomes  2n=30-44
E. glabrescens     ( Glabrous Whitlowgrass)   Chromosomes  2n=52-64

(One cytotype with 2n=24 was only recorded in Germany.)

Key features are:-
E. verna   Variably hairy, petals split more than halfway, leaves tapering to broad stalk, 0.5-1 times as long as leaf blade. (Deep petal groove.)
E.glabrescens  nearly hairless, with longer leaf stalks and less deeply cleft petals.
E. majuscula  leaves densely greyish-hairy, with shorter leaf stalks and less deeply cleft petals.
(Taken from Harrap's Wild Flowers.)

Now if you had the skill and knowledge to do a root tip chromosome count, it would be possible to identify the plants we see but I don't and worse that that, the key features listed in the field guides do not take into account the variation in E. verna. It is not difficult to find plants with a deep petal groove that go from having almost no hairs to very hairy. The deep petal groove suggests these plants are all E. verna ( Common Whitlowgrass).

The chromosome counts indicate that E. majuscula is the original type of Erophila and that evolution has caused more than just a doubling/ tripling/quadrupling of the base number of chromosomes.
 Quite what this range of chromosome counts mean is well beyond my own very limited knowledge. Normally plants go 14, 28, 56  but for example E. verna has been found with 30, 32, 34,36, 40, 42, and 44 chromosomes. This abnormal variation in the number of chromosomes within one species is called Aneuploidy.  Aneuploidy can even occur in the diploid form of some plants ( e.g. Claytonia virginica) but in humans is bad news causing for example, Down's Syndrome.

It is interesting that the polyploid E. verna is by far the most successful type of the three species.

The plant crib article tends to suggest the E. verna leaf is 'lamina scattered to moderate pubescence of mainly branched hairs'. I think this understates the variation of hair density on E. verna.  an example photo follows:-

E. verna from Sutton Gault, Cambs. 14th Feb 2020 Very hairy leaves.

E. verna, same plant as above showing petal cleft/notch.
This Sutton Gault plant is from a population of standard E. verna which have much less hairy leaves, however just a few plants out of several hundred, had this greyish very hairy appearance.

The extent of hairiness appears consistent where plants seem to be clones ( from self pollination) but  a few aberrant plants can occur. The petal cleft is clearly deep but even this feature is not completely reliable. Just occasionally clearly E. verna type plants can have a shortened notch ( this is also noted by Tim Rich in a paper looking at herbarium specimens.)

One might think the grey hairy leaves would make this a E.majuscula but the petioles are too long and the deep petal grooves do not fit the requirements.

Typical E.verna 14th Feb 2020 Sutton Gault.

E. verna showing few hairs 14th Feb 2020 Sutton Gault

Sub-conclusion.   The term 'variably hairy' should not be underestimated. E. verna can vary from very very hairy to almost no hairs. Hairs seem to reduce with age so only new leaves should be considered. This can be seen in the last photo where the lowest leaf has lost most of its hairs.
 Note also the highly variable shape of the petiole and leaves.

Leaves.

What is left to tell these species apart? Next up is the shape of the leaf stem compared to the leaf.  Immediate problem which can be seen in the above photo is where does the leaf start and the petiole finish, as this is not clear to me.  It would seem hard to assess and plants are highly variable.  Some leaves can have a tooth ( or teeth) but this is another variable feature like the hairs being simple or forked.

E verna This plant has attempted to 'self mark' the extent of leaf vs petiole but failed to do it correctly!. Nice try.
One comment is that these leaves do have prominent leaf stalks so that would exclude E majuscula.

Before moving on what does a petal cleft/notch look like.
Petals.

E. verna has cleft from 1/2 to 3/4 of their length
E. majuscula and E. glabrescens , petals bifid to not more than 1/2 their length.

E. verna 14th Feb 2020 Sutton Gault. Normal deep notch in each of the four petals.
E. verna  deep petal notch visible. 14th Feb 2020 Sutton Gault

Petal notch not quite half length, 18th March 2020. 
Petal notch short, 18th March 2020


Petal notch short 27th March 2020

Once familiar with the petals of E. verna the shorter petal notches of glabrescens/majuscula stand out  quite easily. It helps if the flowers are fully open but even if not, the difference is usually clear.  In Erophila some plants are not so clear cut and E. verna occasionally has short notches . In Europe, work by Jordan/Rosen back in the nineteenth century, spilt E. verna into 53 species, some based on petals that were enlarged or had very had narrow petals, so in the UK we are seeing only part of the possible variation.

Stems
The Handbook No 6 shows another feature.
E. majuscula   Flowering stems densely hairy and with at least scattered hairs beyond the first pedicel ( stalk of a flower).
E. verna   Scattered hairs on flowering stems on lower part, upper parts and pedicels no hairs.
E. glabrecens  Flowering stems with hairs on lower part only or no hairs.

Typical E. verna with no stem hairs on upper parts and pedicels but
many hairs will have fallen off at this fruiting stage.
Often E. verna has stem hairs up to the first stem spit and occasionally just above.

E. verna with new stem showing many hairs but the older stem with only a few at the lower end.
A problem with hairs is in Erophila they fall off quite quickly.  By the time the fruit have developed the stems will often have no hairs left, even when they started out very hairy. Stem hairs ideally should be checked at pre-fruiting stage before their number and extent is reduced.

Plants with extreme features that might suggest they are not E.verna.
A) Potential candidate for E. glabrescens

Leaves have almost no hairs. 17th March 2020 Girton, Cambridge.

The plant above was in a group of E. verna but just a few plants had no hairs.
a) The leaves were green with just a few hairs along the margin even when new.
b) The stem had no hairs, even near the base on pre-fruiting stems.
c‚ The petiole ( leaf stem) looks quite long compared to the leaf blade however this seems a very variable feature. I am not sure this can be used to distinguish from E. verna.
e) The sepals surrounding the petals have no hairs. E. verna can have sepal hairs or no sepal hairs. E. majuscula seems always to have hairy sepals.
d) The petals have a notch less than half way.

The combination of the listed features would suggest this is a E. glabrescens.   The seed size is the same as E.verna so there was little point waiting until the plant fruited (fresh seeds 0.5-0.8 mm). The number of seeds in each fruit can be 20-60 for E. glabrescens and 15-50 for E. verna.  The combination of features is the critical factor as any individual feature is not totally reliable. This is very probably E. glabrescens but it is hard to be certain without backing the identification with a chromosomes count.

B) Potential candidate for E. majuscula 
Short petiole gives tight rosette of leaves.  18th March 2020. Isleham Plantation
Enlargement to show new leaves. Note also sepals have hairs.

The compact rosette due to the short petioles is quite different to the normal E. verna growing at the same site.  This feature suggests the plant is a  E. majuscula but it has leaves that are not hairy!.  This would surely be a problem but the new leaves as shown in the enlargement of the rosette, do show early leaves have dense hairs. The leaves are green and shiny but I have seen huge variation in E. verna, so I am not surprised potential E. majuscula could have these features. In fact the Plant crib says majuscula leaves often appear grey , so therefore some do not. The key feature is the very compact form of the rosette caused by the short petioles.

Next step was to check petals notch. Some flowers had a short notch but others were more marginal.

Petal notch less that half way.
Next check if hairs go beyond the first pedicel.

Stem is very hairy and although this photo does not show it well, hairs went beyond the first pedicel.
Stem hairs go up beyond 1st and 2nd junction even when fruiting has started on top right flower.
The stem hairs are often lost by the time the fruits appear so only look at stem with flowers before pollination. Those with fruits will have lost all or most of their hairs. Sepals have hairs.

A small percentage ( est. 5-10%) of plants at this sandy site showed consistent features of very short petioles giving the rosette a compact shape, petals with short notches and hairs that went beyond the first (and second) pedicle.  These plants could be E. majuscula.  

As the population of these compact rosette examples was quite large, well in excess of twenty plants, two samples were taken and potted up, so that seed length could be measured when fruits matured. 

E. majuscula is supposed to have smaller seeds at 0.3 to 0.5mm whereas E. verna/glabrescens has seeds 0.5 to 0.8mm.

 When two plants were measured the first one had seeds in range 0.47 to 0.57mm and the second from 0.4 to 0.59mm, with mean length of 0.54 and 0.5mm. (E. verna seeds ranged from 0.5 to 0.75mm in my sample).   This suggests that in practice there is some overlap in seed length but on average the seed size is less than E. verna.  In Pot 2, some fruit contained seeds that were all below 0.5mm but not all fruit conformed to the expected limit of 0.5mm. All seeds measured were fresh.



1st Plant from Isleham Plantation in Pot 1.
2nd March 2020. Potted up potential E. majuscula, note hairs on stem even at fruiting stage go above first junction.


Plant 1 still in flower on 22nd April 2020.
Enlarged version of above photo showing a few forked hairs on stem above third junction.
You will not see these hairs without a lot of magnification but a few are left even at fruiting stage, in this case at least.

2nd plant from Isleham Plantation in Pot 2

Potential E. majuscula
Seeds from 1st plant

The Erophila aggregate group have had a long and troubled history with several attempts to describe species from Mr Jordan back in 1864 to the chromosome count method used today. The basic problem is relating the chromosome count to features that can be easily observed. The common E. verna shows a lot of variation and the field guides do not describe the complexity.

The reproduction system forming populations of clones and the aneuploidy are surely a warning that separating these three species is not going to be easy.

Hopefully my photos show this group with enough attention to the detail so that some plants can be at least considered as candidates for E. majuscula and possible the even more difficult E glabrescens. Identification has to be based on a full range of features. If only I could count the chromosomes....

The Isleham site for the E. majuscula was found by Alan Leslie.  Interestingly a plant taken by Alan Leslie from the Isleham site had all seeds measuring below 0.5mm showing sample size is a important factor in the determination of limits. Alan's sample has been confirmed as E. majuscula by the BSBI referee Dr T Elkington.


Comments welcome. The season is now over, so we will have to wait until next February to start again to improve our knowledge of these charming plants. The Girton site for the E. glabrescens was found by Jonathan Shanklin. The Isleham site for the E. majuscula was found by Alan Leslie.  At least this year with help from Alan Leslie regarding E. majuscula,  some progress has been made.


Peter Leonard
Rampton
Cambridgeshire
2nd May 2020


The stigma is held very close to the pollen bearing anthers in the open flower on the right and then elongates past the anthers on the left flower.  

From O Winge, 1940  showing just how much work was done on E verna in the past. A small extract follows:-

The present  investigation  confirms  the  view  that  the  Erophiln- 
microspecies  biologically  really behave as a series  of  Linnean species. 
They  are  constant  and  have  different  chromosome  numbers.  Their 
hybrids  are more  or less  sterile,  owing to abnormalities  during  the 
meiosis.  They are able to give constant amphidiploid hybrids.  When 
nevertheless  the collective species Erophila verna is commonly regarded 
as a good  Linnean species  by  taxonomists this  is  the outcome of  our 
defective classification  of  the phenomena in  Nature. 

1940 article at A CASE OF AMPHIDIPLOIDY WITHIN THE COLLECTIVE ...onlinelibrary.wiley.com › j.1601-5223.1933.tb02609.x


Reference of Watsonia paper by Tim Rich and J Lewis 1999 containing in particular comment on how difficult it is to  separate verna from glabrescens in Results section


http://archive.bsbi.org.uk/Wats22p377.pdf


End