Just what is Walchia?

Sternberg created the genus Walchia in 1825. He included every fossil of this kind in this genus. Many species have been renamed since.
In his monography (1939 - 1945) Florin used the name Walchia for a form genus of conifers with unknown cuticle and/or fructifications. The conifers with known cuticle, and sometimes with known fructifications, were placed in the new genus Lebachia.
But later on the name Lebachia appeared not to meet the requirements and it was replaced again (Clement-Westerhof, 1984).
Visscher, Kerp en Clement-Westerhof (1986) distinguish the following genera:

- Walchia for species with well-known cuticle and fructifications, which thus can be placed in a natural family.
- Culmitzschia for species with known cuticle but unknown fructifications.
- Hermitia for the species with both unknown cuticle and fructifications.
- Ernestiodendron with one species, E. filiciforme, of which the leaflets are perpendicular to the axis.
Some species, differing too much from Walchia, have been placed in still another genus.

So this is a complicated situation. It is in most cases very difficult (and sometimes impossible) to distinguish species and genera of sterile branchlets. The names of the Walchia-like fossils in the photos therefore are approximations of the various plant types.