Thursday, 31 August 2017

A Tale of Two Picris

Hawkweed Oxtongue (Picris hieracioides subsp. hieracioides) is a native plant of calcareous soils being found on waysides, old quarries, chalk cliffs and downland. It is always a nice find in Yorkshire as it is not common up here. I have only seen it in VC64 growing on the old walls of Fountains Abbey (photo) and at Burton Leonard Lime Quarries Nature Reserve, although at the latter I must admit I did not determine the subspecies.

In recent years it has become known that several other subspecies also occur, or have occurred previously, in Britain. Most of these are non-native casuals. Generally the native plant can be distinguished from these by its longer branches and capitula on relatively long pedicels.

This came back to me today when I stumbled across a small colony of Hawkweed Oxtongue in Rothwell Country Park (VC63). This is not a location where the native would be expected, as this site is restored colliery land and was sown with a seed mix in the past. Sure enough this plant did not look quite right, with me having at the back of my mind that if it had some capitula near-sessile it was worth a closer look.

Of course coming home and revisiting the above photograph the differences are quite obvious. The current plant is subsp. villarsii (its synonym of subsp. umbellata is more descriptive). It has flowers arising in tiers on short branches, and the terminal inflorescence is sub-umbellate. Of course this latter trait was most obvious in the plant I decapitated for ID purposes, so I did not get a photograph in situ but I did manage to salvage a few photos later (see below). The phyllaries are meant to be blackish-green, this seems a bit variable and was not as pronounced as I was expecting from reading the key previously. It is probably less useful than the other characteristics of the inflorescence, but perhaps it darkens when pressed.

Sunday, 27 August 2017

Sparganium erectum - Getting to Grips with the Subspecies

Mike Wilcox is taking an interest in Branched Bur-reed (Sparganium erectum) at the moment, with the aim of improving knowledge of the distribution of the four subspecies. Much needed, and particularly valuable for the New Atlas project.  It is too easy to ignore variation below the species level, but in recent years we have seen a number of under-recorded subspecies raised to species status leaving a black hole in our records as a result. Even where this is not warranted the ecology and geography of the component subspecies can diverge and is in itself interesting.

                                   Sparganium erectum subsp. microcarpum on the Ripon Canal. Image: M. Wilcox

So ideally we should be recording subspecies, although it is not always easy especially when published descriptions are often inadequate. It is too easy to make a false start, reducing confidence and increasing the inclination not to try. Which neatly brings me back to Mike, who is keen to receive samples of mature fruiting heads from anywhere in the UK and Ireland and will provide or confirm the initial ID's. So its win win for all concerned.

There are four subspecies in the UK & Ireland, all of which are detailed in our standard floras. So they are doable, but only with mature fruit (so now onwards is a great time to collect fruit) and being aware of the pitfalls in the key. The split between subsp. microcarpum and subsp. neglectum is particularly tricky as it relies on a judgement as to whether the individual fruit are 'shouldered' or 'gradually narrowed'. See Mike's photo of the former and note the difference between the mature fruit and the immature fruit. Subsp. microcarpum might perhaps be better described as having a domed head as it is not markedly shouldered, and subsp. neglectum as tapering. There is a great picture of the latter (and subsp. erectum) here.

If you would like to get in touch with Mike his address is in the BSBI members handbook (Members area of the website) or drop him an email. Fruiting heads can be put into a paper packet or envelope, and full details of the location should be provided (there is no value in a record if we don't know where it comes from!). You can email Mike at michaelpw22[at]  (replace the [at] with an @).

Friday, 18 August 2017

The 'Grey Man' of the British Flora

The 'grey man' concept is about surviving by never drawing attention to yourself, blending into the background, giving no lasting impression. Sea Pearlwort (Sagina maritima) has this down to a T. Poor thing.

Photo by Geoffrey Hall, NatureSpot website for Leicestershire & Rutland

I suspect I have been overlooking this annual species, and I suspect this will be case for many others also. Particularly those like me who largely botanise inland and therefore do not have this species on their radar as a possibility. Mike Wilcox has recently drawn my attention to the presence of this species at St Aidan's (VC64), and having been for a look I had seen it previously and just ignored it as seedling Procumbent Pearlwort (Sagina procumbens). How wrong I was. After this I found it in pavement cracks in Leeds (VC63). Mike knows this species well from Bradford, about as far from the sea as you can get.

Photo by David Nicholls, NatureSpot website for Leicestershire & Rutland

Part of the problem is that this species is very variable, and many populations comprise tiny plants (2 pence coin size), so it is easily missed. Published descriptions are also not adequate, for example in Stace it is described as 'diffusely branched +/- erect annual'. Not strongly prostrate as per my plants and the photos above. The associated key also links the species to other annual species, the unintended mental image of which (coupled with the description) is a plant similar in character to these other species. The key jizz of the plant as shown above is a central rosette with flowering branches arising around its margins, and no sterile shoots (unlike the perennial species).

I was please to have opportunity again to use my bargain £10 macrolens for my iPhone. Quite pleased with the result below.

Sunday, 13 August 2017

It's Hawthorn Time

I've blogged previously on the abundance of Eastern Hawthorn (Crataegus x subsphaerica), but there are still very few dots in the BSBI database other than mine and those for Cambridgeshire, Cardiganshire and the London area.

Now (and until well into October) is a great time to go out and look. Look and ye shall find, probably very quickly. The sepals are rising! See my other posts (link to Crataegus in side bar) for typical forms. But if it has erect sepals it is probably (given its abundance) Eastern Hawthorn, or potentially its much rarer parent Saw-toothed Hawthorn (Crataegus rhipidophylla). There are other hybrids, but if in doubt over parentage there is usually a bush nearby showing a clear influence from Hawthorn (Crataegus monogyna).

Once your eye is in on leaf shapes and fruit characteristics, it is quite easy to spot suspect bushes. Particularly if showing hybrid vigour or if they have the large distinctively-shaped fruit.

Its more tricky with the form with reflexed sepals (nothovar. subsphaerica), particularly when closer to Hawthorn. But again large fruit, and the longer than wide sepals, will give the game away in many cases. I found a nice bush today, photo below

Both forms are widespread around Leeds as plantings, but are also widely naturalised and show the characteristics of a hybrid swarm, with all possible variants from one extreme to the other due to back-crossing. However, most are somewhere in the middle.

Sunday, 6 August 2017

The World's Smallest Centaurium pulchellum?

During my recent July 'botanise-athon' I popped into Fairburn Ings, I fancied seeing what the river had to offer and wanted to have a look at the dog-roses in the knowledge that Rosa canina is soon to be formally split (at least in terms of our standard literature) into three species (canina, corymbosa and squarrosa) rendering most records to-date to aggregate status.

Anyway, I went round to the boot of my car to put my walking boots on and there at my feet were lots of a tiny Centaurium. Of course I new Lesser Centaury (Centaurium pulchellum) was here as a dwarf form, as Phyl Abbott had found it a couple of years previous new to VC64. I just thought I would need to do a lot more looking to find it. It was associated with the narrow strip of gravel along the edge of the car park, so I assumed it had been introduced with this substrate. It is a very rare plant in Yorkshire and indeed this far north where it is mainly coastal.

However, this was not the last I saw of this little gem. Pottering round an area of acid grassland, where there were extensive bare patches where water stands in the winter, I was surprised to find 100's of plants. All tiny and predominantly single stemmed with just one flower on top. Clearly this is a dwarf race, breeding true and undoubtedly maintained by selfing, rather than just an environment induced phenotype. Being so small I doubt it is troubled by pollinators any more, so it has painted itself into a bit of a genetic deadend. But it seems quite happy at the moment and should persist as long as there are areas of bare ground with no competition from larger plants.

Elsewhere there some great stands of Honeysuckle (Lonicera periclymenum var. periclymenum).

And a small colony of this garden favourite, Rose Campion (Silene coronaria).