Tree
Evolution
Most botanists believe that the first land plants were herbaceous. The first woody plants were probably Lycopsids, free-sporing plants which had narrow, tubular grass-like leaves. Numerous Lycopsid fossils have been dated to the middle of the Upper Devonian period, more than 370 million years ago. The first known plant with a vascular cambium which exhibited true secondary growth was a species of Protopteridium, a free-sporing plant dated to about 370 million years ago.
Very few modern, free-sporing plants are arborescent. The only living relatives of the Lycopsids are the club mosses (Lycopodophyta), a group of simple, herbaceous, free-sporing plants.
Additional topics
Science EncyclopediaScience & Philosophy: Toxicology - Toxicology In Practice to TwinsTree - Tree Taxonomy, History Of Taxonomy, Modern Taxonomy, Cell Layers In A Tree Trunk, Growth Rings - Secondary growth