bullace / corydalis / valley heights of Yorkshire
The plum orchard was bulldozed by Blooper Homes, but there was an unexpected compensation. Among the other things they cut down was a big ash-stool behind the garages, and this exposed (what I'd never noticed before), a bullace well-loaded with fruit. So we'll have pie this year after all.
There seems to be no botanically-acceptable distinction between damson and bullace. Of the numerous distinctions that are claimed, the most credible is Mrs Grieve's, that damson fruit is somewhat oval whereas bullace fruit is round. Also, the word damson always seems to imply a dark purple fruit, whereas bullaces may be any colour including green and gold. And generally you more often hear of damsons in a garden context than a hedgerow context.
So perhaps the best way of seeing it is that the word "damson" is used to name a particular group of varieties of "bullace", which in turn vaguely designates those plums that are more sloe-like than most, i.e. with smaller fruit, downy twigs, and occasional thorns.
[In 2015 the subject was discussed on the Facebook Wild Flower Group. The following ID tips come mostly from Richard JD Smith and Richard Collingridge.
1 .Cherry-plum (P. cerasifera)
Thornless, more or less
Fruit round, ripens early (the earliest plum), sweet-tasting; purple, red, orange, yellow, white.
Flowers, earliest, with leaves
2. Blackthorn/Sloe (P. spinosa)
More fruits in a cluster than 3 or 4
Fruits small, globose, extremely astringent (skin) and sour (flesh). Black-purple (may look blue because of bloom)
Fruit-stones not or scarcely flattened
Flowers, later than 1, before leaves
3. Bullace (P. domestica ssp. institia, var "Bullace")
Shrub or small tree
Usually not or scarcely thorned, but sometimes thorny.
Fruits less in a cluster than 2
Fruit usually larger than 2 (typically about double the diameter); smaller than 4. Globose. Sweeter than 2, but skin may still be astringent. Black-purple, also yellow-to-reddish ("Shepherd's Bullace")
Fruit-stone more flattened than 2.
Upper leaf shiny
Flowers, slightly later than 2, with leaves
4. Damson (P. domestica ssp. institia, var "Damson")
Rarely with any thorns
Fruit earlier than 3, larger and more oval than 3. Sweeter than 2. Purple.
Upper leaf not shiny
Twigs not hairy
Flowers, slightly later than 2, with leaves ]
And since it's at that fruiting time of year:
The rather faded notice at the base of Hambleton Hough in Yorkshire tells us that the flora of this mountain includes "Climbing White Fumitory". Once you have ascended the 35 meters from here to the summit (we used GPS to check this) you'll find the plant in most seasons - Climbing Corydalis, (Ceratocapnos claviculata, formerly Corydalis claviculata). The name "White Climbing Fumitory" is not found in McClintock and Fitter nor in any flora since, but it still clings on from the botanical past. It isn't a good name, though. The fruit of Fumitory is an achene, while Corydalis fruit is a capsule.
Achene - a dry, 1-seeded, indehiscent fruit.
Capsule - a dry, many-seeded, dehiscent fruit.
They never explain this stuff in the wild flower books, but I suppose the logic is this: if a fruit contains more than one seed, then it needs to scatter them to prevent them all germinating in the same place. Therefore some sort of process of breaking open (dehiscence) and scattering of the seed is more or less inevitable (there are a few exceptions). On the other hand, if there's only a single seed, then it might as well hang on to its protective fruit-coat until germination.
(Several attempts to use supermacro in a dark wood at sunset - not a good combination...)
John Durkin writes, on the BSBI site:
"In County Durham it could almost be said to be an indicator of PAWS woodlands (plantations on ancient woodland sites), being often abundant under conifers on ancient woodland sites, but very scarce in broadleaved ancient semi-natural woodland and almost unknown in recent plantations. PAWS woodlands on slightly acidic glacial sands have the best populations."
That describes Hambleton Hough perfectly, where the natural woodland was cut down by a former owner and replaced by Scots Pines. The ground flora is bracken and very little else, and yes, it is a glacial deposit left behind by the Humber glacier in the otherwise dead-flat part of the Vale of York. Well, apart from its neighbouring twin peak, Brayton Barf, which also has plenty of C. claviculata.
Hambleton Hough and Brayton Barf are accumulated heaps of glacial debris that built up around an original nub of Bunter Sandstone (Triassic). The debris is mainly coarse sand of a reddish cast. I like to imagine that this sand was scoured off North Yorkshire sandstone cliffs like those still to be seen at Sutton Bank, but this may be wrong.