Various-leaved Hawthorn (Crataegus heterophylla)

Various-leaved Hawthorn (Crataegus heterophylla) is one of those frustratingly elusive species, you know its out there but can never seem to find it. To the extent that it starts to feel a little mythical. This is not helped by the lack of any more than a handful of images for this obscure species, which is only known in cultivation and as an introduction. Pretty much every image that there is to be found is on Wikimedia Commons. The best of which is this one:

I did find a bush a few years back in the Dales that I thought could be this species, but I lost confidence in the ID and decided that it might just be very atypical Common Hawthorn (C. monogyna). Similarly, there have been other bushes in hedgerows around Woodlesford (VC63) that seemed close to this species, but with leaves that were too deeply lobed. 

So it was a milestone moment this year, while scrutinising a hedgerow on the edge of arable fields at Lowther Lake (VC64) that I had not previously looked at closely, that I found amongst an array of other taxa a bush that could only be this species. It is of planted origin, but is now well established and is fruiting well.

It is important to look at the flowering shoots, which have leaves of variable shape but with lobes in no greater than the upper two fifths of the leaf blade, a distinctive narrowly elongate outline, and a markedly cuneate base. The leaves on non-fertile shoots are very different and contrast strongly with the leaves on fertile shoots. The fruits also seem slightly smaller (less plump) than those of Common Hawthorn, with reflexed narrow (longer than wide) sepals.

This discovery also provided a frame of reference for other local hawthorn bushes that have been bugging me for several years. These have the distinctive lobing and narrow leaf shape of this species, but are too deeply incised. I now think these are hybrids between Various-leaved Hawthorn and Common Hawthorn (Crataegus x subheterophylla). They seem more frequently planted than Various-leaved Hawthorn, matching observations of other hybrid hawthorn taxa and other 'look-alikes' and 'false natives'. Growers seem incapable of keeping their stocks pure, and hybrid swarms seem to be increasingly propagated and distributed for planting in wild settings, for ecological mitigation and for nature conservation. Eastern Hawthorn (Crataegus x subsphaerica) is another example of this, and one that I have flagged previously as being widely over-looked and under-recorded. We may not like it, but increasingly I think we will need to recognise that hawthorns are (at least in many lowland settings) best determined in fruit. The species and hybrids are so variable in foliage, and the hybrids generally occupy a complete spectrum between both parents. 

A few examples of what I consider to be good candidates for Various-leaved x Common Hawthorn below.

Postscript to the above:

Having found my 2017 photos from Stainforth in the Yorkshire Dales (VC64) and looked at them again, I think this hawthorn also can only be Various-leaved Hawthorn. If anything its an even better candidate than the above. How it got onto Goat Lane would seem the bigger mystery. I can only assume it has bird sown from either an amenity planting somewhere lower down the valley.

Crataegus x rubrinervis

I popped over to Skelton Lake (VC64) today to check up on the bush of Crataegus x rubrinervis (Common Hawthorn C. monogyna x Five-seeded Hawthorn C. pentagyna) I first found in 2018. There are a couple of bushes of Five-seeded Hawthorn a few hundred metres away, and this bush looks like it has arisen in situ.

It has the foliage, large succulent fruit (at their largest they are blackcurrant sized) and suberect sepals (recurving at the tips) of Five-seeded Hawthorn, but with fruit dark red to red-purple rather than purple-black and seeming to ripen later as well. The flesh is reddish coloured, and in this case most of the fruits checked had two pyrenes, but a few had three.

Bottom Boat and Back

I made the most of the good weather on Tuesday to walkover over to Bottom Boat (VC63). Its not a route I do often, as it requires a bit of a slog up and over the ridge that separates the Aire Valley from the Calder Valley, but it does offer potential for interesting casuals and escapes and usually provides something of interest.

The day started well before I had even left Oulton with some particularly robust Cockspur (Echinochloa crusgalli) on an arable margin. This seems to have sprung from nowhere given I walk pass this field regularly.

Reaching my target destination I stumbled on a patch of derelict hardstanding with a variety of interesting garden throwouts. This is where I met 'Angelina' (see previous post). Other highlights included:

The golden form of Wilson's Honeysuckle (Lonicera nitida 'Baggesen's Gold').

Pink-sorrel (Oxalis articulata), in association with Stinking Hellebore (Helleborus foetidus) and surprisingly, as I did not know that it can throw up leaves in autumn, Garden Grape-hyacinth (Muscari armeniacum).

Stinking Tutsan (Hypericum hircinum).

Slightly further on, this attractive bi-coloured cultivar of Broad-leaved Everlasting-pea (Lathyrus latifolius 'Blushing Bride') was still going strong.

While an arable margin nearby had the winged form of Black-bindweed (Fallopia convolvulus var. subalatus). Supposedly less common than the nominate form, but that is not my experience.

Working my way down towards the River Calder I moved into abandoned former colliery land. Not the richest of habitats, it needs a few more decades yet, but still with interest and its great that no one has tried to 'restore' it. 

By the farm track on route was a young and apparently self-established tree of Cherry Crab (Malus x robusta), a variable group that perhaps includes plants of other origin. One of the characteristics of this species is that the individual apples are variable in terms of whether or not they retain their sepals. I think it likely that the fruit will colour further, they were in shade so a little behind.

Heather (Calluna vulgaris) is already starting to move in amongst the secondary birch woodland, a species that is very uncommon in the lowlands of Leeds and Wakefield.

But keeping with the theme of unusual non-natives there is also a thicket of sapling Broad-leaved Cockspurthorn (Crataegus persimilis 'Prunifolia'). No idea how that arrived, but it does not look planted. It proved the first of several interesting (at least to me) hawthorns.

Further on, the landscape architects had been in at some point in the last 30 years 'restoring' the landscape and creating 'native woodland'. Of course its nothing of the sort, rank MG1 grassland and the usual mix of false natives and lookalikes. Among these was a tree currently going by the name of Miyabe's Maple (Acer miyabei). The true species is of Japanese origin and, like Alan Leslie notes in Flora of Cambridgeshire, I think our plants are probably something else. The question is what? Potentially it is an unnamed alien form of Field Maple (Acer campestre), but possibly as with many planted 'native' hawthorns, dogwoods, Viburnums and hazels it could be of hybrid origin. Its a striking tree though, with large leaves, long petioles and large keys (glabrous in this case but they can be hairy). The second photo below contrasts it with typical field maple (var. campestre).

There was also Coralberry (Symphoricarpos orbiculatus) and  the hybrid hawthorn Crataegus x subsphaerica. The latter in this case had foliage closer to Common Hawthorn (Crataegus monogyna) but with clear hybrid vigour, but those elongate erect sepals give the game away.

One final hawthorn brightened the walk home. Check out the haws on this Common Hawthorn, c. 13mm long by nearly that wide. Living up to its name of var. splendens. These large fruited bushes occur here and there amongst more typical plants. I'm not quite sure what to make of them (valid variety or just chance?), but they make a stunning sight in the autumn sunshine. The bottom photograph compares it with more typically sized haws from a neighbouring bush.

Interesting Trees

In sorting out photos from the last couple of months, I realise that I have quite a few photos of unusual trees that may be of interest to others. So for an easy post ...

2020 seems to have been an exceptional year for blossom, with a non-stop heady rush that was perhaps over a little too soon. One tree I always look out for a few weeks after the Wild Cherry (Prunus avium) flowers, is its double-flowered cultivar 'Plena'. This can be found in plantation woodland around the boundary of Oulton Park (VC63).

Near the above tree, is the double flowered cultivar of Horse Chestnut (Aesculus hippocastanum 'Baumanii'). I have been walking under this tree for years and never noticed it, but perhaps work commitments in a normal May mean I have never passed at the right time. I find its stumpy little candles rather unexciting, and that probably explains why its not seen more often. Foolishly I seem to have mislaid my photos, so here is an image from the Deepdales nursery website.

Unusual Sycamores (Acer pseudoplatanus) always catch my eye, and a favourite is f. variegatum 'Simon-Louis Fréres'. There is a fine tree in the churchyard at Swillington (VC64).

This handsome Common Whitebeam, at the edge of plantation in Water Haigh Woodland Park (VC63) is Sorbus aria 'Lutescens'. It remains white well into the summer when the young fruit are markedly pubescent.

In complete contrast this (I think) is Sorbus aria 'Majestica', with very large glossy leaves. It has been planted on the boundaries of Swillington Brickworks (VC64).

At the same location, Purple Filbert (Corylus maxima 'Purpurea') has self-sown from an unknown source. I think I am on safe ground (in the absence of fruit) with the ID given the excellent purple coloration, but most hazels encountered from introductions seem to be hybrid Kentish Cob types. Last year I found some of these with pale muddy purple leaves suggesting 'Purpurea' in the parentage.

The woodlands round the capped landfill at Newsam Green (VC64) include a few trees of Paperbark Birch (Betula papyrifera) amongst the Silver Birch (Betula pendula). These are only just reaching an age where the bark turns white, and the juvenile bark can be confusing.

Finally, to encourage more people to look at hawthorns as they come into fruit later this summer, here is a compare and contrast between the typically (not always, its not definitive) small-flowered Hawthorn (Crataegus monogyna) and its often large-flowered hybrid with Large-Sepalled Hawthorn (Crataegus rhipidophylla) i.e. Crataegus x subsphaerica. The hybrid is common and spreading locally, and probably elsewhere. Flower size is often a good way to pick out the non-native hybrid and its parent. However, the hybrid usually (but not always, some forms have clearly intermediate foliage) needs to be confirmed later when in fruit. Therefore, the large flowers may be the first indication that there is something potentially interesting to check again later in the year.

Buttercups and Hawthorn

After a long break, I'm well overdue picking up this blog again. 'Lockdown' has provided an opportunity over recent weeks to explore familiar sites and routes in closer detail, and I have been pleased to find plants not noticed before. Some plants have probably only been missed in previous years because the last time I walked that way they were obscured by other vegetation. The positive of lockdown botanising is that you walk the same routes over and over again as the season changes.

I have collected more photos along the way than I've yet found the energy to turn into blogs. So to get me started again, I am going to try and post regular snippets rather than try to be more ambitious.

First up are two attractive forms of native plants found yesterday. One is a truly wild, while the other will be of planted origin.

The former is this stunning form of Bulbous Buttercup (Ranunculus bulbosus) found in a pasture near Scholey Hill (VC63). Three plants mixed with others of typical flower colour. This seems comparable with (but isn't) the cultivar known as 'F.M. Burton.'

Next up at Oulton (VC63) was this hawthorn (Crataegus x media 'Punicea') in a hedgerow between two arable fields. It is supposedly a form of this native hybrid (its nothing like Midland Hawthorn C. laevigata, despite some references stating this) but if so its seems to be much closer to Common Hawthorn (C. monogyna). I did find one photo online that suggests that it might occasionally produce two styles rather than the usual one, but as per Stace this is not 100% reliable for the hybrid. I also note that Sell & Murrell list it under Common Hawthorn, so it seems the species affinities are yet to be adequately resolved.

Black-fruited Hawthorns

I have blogged previously about some of the more unusual hawthorns gradually filling up our countryside, and I always like to keep my eyes open at this time of year for anything that might be different. Some recent finds are still defeating a name.

Last Sunday I was caught a little by surprise when I looked up into a hedgerow near Skelton Lake (VC64) and saw a lot of large black fruit dangling down. These were very succulent, with red-tinged flesh under the skin. Further examination revealed 3 pyrenes per fruit. So instantly my brain was thinking, and regardless of the common name, Five-seeded Hawthorn (Crataegus pentagyna). This species has 3 to 5 pyrenes. This identification was later confirmed at home using a combination of Sell & Murrell and the monograph by Christensen. If I'm honest the latter seems to be a little more user-friendly, and perhaps more representative of the variation present in this genus of notoriously variable species. But both are useful, and its nice to be able to compare and contrast.

Further on I found another bush with comparable fruit but very different foliage. I initially thought it was a hybrid, but it just seems to be a variant of the species (most hawthorn species being highly variable).