• Taxonomic hierarchy:

• Species: Prunus spinosa (Blackthorn, Sloe)
• Genus: Prunus (plums, cherries and laurels, planted cherry)
• Family: ROSACEAE (roses and fruit trees)
• Order: ROSALES (roses, elms, nettles, hops, buckthorns and figs)
• Subclass: EU-DICOTS (dicotyledonous flowering plants)
• Class: MAGNOLIOPSIDA (flowering plants)
• Phylum: TRACHEOPHYTA (vascular plants)
• Kingdom: PLANTAE (plants)
• Domain: Eukaryota (eukaryotes)
• Life: BIOTA (living things)

• Prunus spinosa is also a member of:

• Soft Fruit - treees, bushes and plants that are grown for soft fruit (via Prunus)
• Broadleaved shrubs - broadleaved shrubs (via Prunus)
• Broadleaved trees - broadleaved, frondose or deciduous trees (via Prunus)
• Endomycorrhizal broadleaved trees and shrubs - endomycorrhizal or endotrophic mycorrhizal broadleaved trees and shrubs (via Prunus)
• Endomycorrhizal trees and shrubs - endomycorrhizal or endotrophic mycorrhizal trees and shrubs (via Endomycorrhizal broadleaved trees and shrubs)
• Broadleaved trees and shrubs - broadleaved trees and shrubs (via Endomycorrhizal broadleaved trees and shrubs)
• Xylophytes - broadleaved trees, shrubs and woody climbers (via Broadleaved trees and shrubs)
• Endomycorrhizal plants - plants that form endomycorrhiza (via Endomycorrhizal trees and shrubs)
• Trees and shrubs - trees and shrubs, including conifers (via Endomycorrhizal trees and shrubs)
• Trees - broadleaved and coniferous trees (via Broadleaved trees)
• Trees, shrubs, woody and climbing plants - trees, shrubs, subshrubs and climbers, including conifers (via Broadleaved trees)

Notes:

Scrub advancing from hedge in a way that Cherry Plum etc never do.

The buds were just beginning to show white petals at the tip, whereas Chery Plum has been out for a week or two.