Ptyxis Ecology - Our Botany Blog

Sunday, 31 October 2010

Looking for a plant identification, botany or habitat survey training course?

We are running a programme of plant identification courses aimed at professional ecologists and interested volunteers again in 2011. See or email us on for a Booking Form & prices. Our courses are the same price as most ecology CPD, at between £60 and £80 a day (no VAT).

Our courses include:
•Phase 1 Habitat Survey
•Grasses, Sedges & Rushes for Phase 1 Habitat Survey
•Identifying Invasive Plants on the New Schedule 9 List
•Using the Wild Flower Key: Botany for beginners & the top 10 plant families
•Identifying Grass Indicator Species in Flower
•Advanced Grasses
•Plant Indicator Species for Phase 1 Habitat Survey
•Introduction to Aquatic Plants
•Sphagnum Identification & Ecology
•Introduction to Bryophytes as Indicator Species

There are still few organisations offering this type of botanical CPD training in the UK. Many are unaccrediated courses, which means that the quality of the teaching is not independently monitored. This is probably OK if the tutors involved have their work regularly checked anyway as they teach for universities or colleges or other awarding bodies with QA processes, but many courses never mention who is actually doing the teaching - and if they do, few state that their teaching is independently assessed. Being a professional ecologist does not mean that you know how to teach professionally! Professional teachers have to do CPD, just like ecologists, so they should be striving to improve their courses and, for example, have evidence to show that they can cater for mixed abilities in their groups.

It is also important to realise that attending an identification course is a great start, but that you need to practice regularly (by which I mean at least once a week, every week over the summer season) to retain and develop the as with any field of expertise, it helps if you really love the subject (and being outdoors)!



Hybrid thistle

A local botanist, Phill Brown, found this strange looking thistle about 2 or 3 miles from where we live
You can see that it is quite a robust plant, with large, fairly flat leaves that are deeply lobed.

The inflorescence is similar to melancholy thistle Cirsium heterophyllum, but perhaps a bit narrower than normal. The top of the stem has no spines and only weak ridges or wings, which also almost fits with Cirsium heterophyllum. It would have no ridges on the stem at all. This is a character not found in most other British thistles.

The word 'heterophyllum' means variable leaves and Cirsium heterophyllum can have both unlobed leaves or lobed leaves like these. The dense cottony underside to the leaves is also a Cirsium heterophyllum characteristic.

However, the undulate (wavy) margin to the leaf with strong spines, does not fit with Cirsium heterophyllum and this photo shows a leaf resembling those from marsh thistle Cirsium palustre, but broader and more robust.

You can also see the undulate spiny margin on this more-or-less entire leaf from the same plant.

Additional characters that fit with Cirsium palustre more than Cirsium heterophyllum include: height (Cirsium heterophyllum is normally shorter); well-spaced leaves along the stem; long branches; and shoots all from a single rosette (Cirsium heterophyllum normally has lots of vegetative growth about the base). In addition, the plant was pretty infertile with only 8 normal-looking seeds from 3 flower heads.

Initially it was the overall 'odd' appearance of the plant, plus the combination of Cirsium heterophyllum type lower leaves and the degree and nature of the branching, that caught Phill's attention and caused him to suspect that he had found the (unfortunately named) hybrid between the two, Cirsium x wankelii. The combination of aditional characters from both Cirsium heterophyllum and Cirsium palustre listed above, helped Quentin Groom to confirm the identification. This is only the third record for this hybrid in England!

That process of identifying a hybrid by assessing all of its characters and comparing them to possible parent plants, is typical of how hybrids have to be identified. Hybrid identification probably qualifies as a 'dark art'. Part of the trouble is that you can rarely fit hybrids neatly in to keys to species, as they are too variable. This variability is often due to back-crossing (i.e. hybrid plants crossing again with one of the parent species. This means you can get hybrid plants that are very close morphologically to either parent and other hybrid plants at stages in between the two extremes. That is just too much variability to accomodate in a dichotomous key usually. Where there is not so much back-crossing, it is usually less of a problem and genuinely intermediate plants are more common. An exception to this involves Roses which have an unusual way of inheriting genes from their parents (split 20-80, instead of the normal 50-50).

Even without back-crossing, first generation hybrids are not necessarily intermediate in every character between the two parents. There are several reasons for this, e.g. some characters are associated with dominant and recessive genes, so the morphology in the hybrid plant will resemble the parent plant with the dominant gene entirely.

As they can be so tricky to identify, it is often useful to collect some more information about the plant. What other species from the genus are growing nearby? If both potential parents are growing right next to the hybrid that is reassuring, but not absolutely necessary or conversely, not absolute proof in itself.

Most hybrids are at least partially sterile and so at least some will not form viable seeds. Sterile seeds often look shrivelled and empty compared to viable ones. However sterility in hybrids can vary between 100% and 0%. For this character to be useful, you really need to have some knowledge and experience of what the normal range of sterility is for the particular hybrid that you are dealing with. This information is not included in popular books, so you need to have access to specialist texts, or to someone with a particular expertise in the group of plants you are dealing with.

Hybrids often have some sterility in their pollen. This can be checked easily under the microscope by putting some pollen in stain. The viable pollen is usually coloured and full, whereas the sterile pollen appears shrivelled and colourless. You simple count how many of each type you have and from that work out the percentage fertility. Again for the results to be meaningful, you need to have some experience with the particular hybrids.

On top of all of that, of course, sterility can be caused by environmental factors, so just because you have some sterility, does not mean necessarily that it is a hybrid!

This all sounds complicated, but it is really a simplified account of some of the factors you consider with hybrids. It is no wonder that most people interested in plants groan in despair at the mere mention of the word hybrid.


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Monday, 25 October 2010


This year I have been busy doing a big upland National Vegetetion Classification (NVC) survey on a site near where I live, covering about 3,000ha. Its been really hard work doing such a large survey by myself, but at last, I've nearly finished it!

My favourite habitat on the site is labelled as 'H21a' in the NVC. This is a habitat that is easy to recognise - heather and/or other dwarf shrubs, with Sphagnum beneath and no hare's-tail cottongrass. Around here, it usually occurs on steep (c. 45 degrees) north-facing slopes.

This is a very nice example of the habitat on a very steep (>50 degrees) slope. As the site is right on the north edge of the Pennines, there are lots of steep north-facing slopes. But you find it throughout the North Pennines, particularly in narrow strips along the north side of east to west stream valleys.

Here is a close-up showing some red Sphagnum in amongst the dwarf shrubs. You can get 4 red Sphagnum species from Section Acutifolia in this habitat - capillifolium, russowii, subnitens and quinquefarium. This is more or less the only habitat that S. quinquefarium grows in around here.

I suspect that this habitat is often overlooked in the Pennines for several reasons: it often occurs in strips of habitat that are too narrow to map; it occurs on steep slopes that are more difficult to walk along than the more gentle slopes on the top, which are usually covered by blanket bog; it looks superficially similar to blanket bog, just lacking any hare's-tail cottongrass; and all habitats with prominent bryophytes are overlooked and misunderstood, as most surveyors can't identify any bryophytes.

The shots aove show a very open sward of dwarf shrubs, but more usually there is a thick sward of dense heather with patches of Sphagnum here and there. Sometimes (on grazed sites) you get a lower sward with bare patches. It is always worth looking closely at these areas as here you often find locally or regionally uncommon liverworts. Recently, I have found Barbilophozia atlantica, Kurzia trichoclados and Lophozia incisa in patches of this habitat.

In the north and west of Scotland, whole hillsides can be covered with this habitat and the best spots have H21b, which is a version of the habitat that is much richer in liverworts. Not only are liverworts abundant in H21b, but there are usually rare oceanic species included. This is what bryologists refer to as the 'Northern hepatic mat'. Along with atlantic temperate rain forest, H21b is probably one of the most special habitats in Britain as there is more of it here than anywhere else in the world. In the North Pennines. although we get some interesting liverworts in H21a, it would be stretching it too far to refer to this as a 'hepatic mat', as there are usually only small patches of liverworts in our examples.


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New things to look out for in the autumn

Quentin Groom sends the following pictures and text about Conyzas:

Conyza canadensis (Canadian Fleabane) first established in the North-east in the 1990s and is now well established in Newcastle, Gateshead and Hexham.

Close-up of C. canadensis infloresence.

Its taller, hairy cousin C. sumatrensis (Guernsey Fleabane) has become established around the station in Newcastle over the past two years.

Both look similar, but C. sumatrensis is distinguished by having much hairier flower heads and a distinctly cone-shaped inflorescence. C. canadensis has hairless or slightly hairy flower heads and a columnar inflorescence. The shape of the inflorescence is a difficult character to grasp, until you have seen it in the field. However, once you’ve got used to it, it allows you to spot each species at a distance.

Both species are urbanophytes and they grow in pavement cracks, walls, gutters and other microhabitats of the urban landscape. They are expected to increase!


PS. I first started botanising seriously when I lived in London in the late 1990's. By that time C. sumatrensis had become probably the most common plant in Central London even though it had not been recorded at all when Rodney Burton's 'Flora of the London Area' was published in 1983.