Wych elm (Ulmus glabra) is a traditional British/European hardwood with an interlocked grain that produces swirling figure and good toughness. It has that distinctive “stringy” feel typical of elms, and it holds fasteners well while resisting clean splitting.
Compared with English elm it’s generally easier to work, but interlocked grain still means planing can tear on quartered faces unless cutters are sharp and you work with the grain. The ring-porous structure gives it an open texture that can be left natural or filled for a flatter finish.
Elm is classed as non-durable in normal outdoor exposure, but it performs remarkably well when kept permanently wet, which is why it appears historically in waterworks and submerged structures. In modern woodworking it’s best treated as a characterful interior timber with a unique grain and a long, water-linked history.