Charcoalify

Periodic wildfire swept through the seasonally dry heaths, consuming the more flammable components of the vegetation such as conifers but charcoalifying the thick, heavily cutinized and comparatively resin-deficient Phlebopteris fronds.

Source: wiktionary

Fig. 3.2.3.1[…](d,e) Angiosperm wood charcoalified by hot ash fall, Montserrat;

Source: wiktionary

Wood and leaves are more likely to decay but even these can have their preservation potential increased dramatically by being charcoalified by partial burning prior to burial.

Source: wiktionary