Evolutionary history of plants phloem on the outside. Since xylem cells comprise dead, lignified tissue, subsequent rings of xylem are added to those already present, forming wood. The first plants to develop secondary growth and a woody habit, were apparently the ferns, and as early as the Middle Devonian one species, "Wattieza", had already reached heights of 8 m and a tree-like habit. Other clades did not take long to develop a tree-like stature. The Late Devonian "Archaeopteris", a precursor to gymnosperms which evolved from the trimerophytes, reached 30 m in height. The progymnosperms were the first plants to develop true wood, grown from
Stars named after people generally considered disused—some sources listing them as "traditional". It is possible, though unlikely, that further traditional names are in fact hidden names such as these, not yet identified; etymologies for many star names are not currently known. Whilst many private companies will offer the "right" to name a star, for a fee, they have no legal standing to assign any star a name, and can offer no guarantee of the name being noted. The IAU does not recognize this practice and its website uses the word charlatanry in this context. Stars named after people Over the past few centuries, a