twig, Chinese black pine
槇 centers on a specific type of pine tree, the Chinese black pine, and by extension its twigs or branches.
槇 combines 木 (tree) with 眞, which likely contributes a phonetic element. The character specifically names the Chinese black pine.
A tree 木 with the component 眞 on the right: picture a distinctive pine tree whose twigs are used to make something genuine or true, like a traditional tool.
For テン, imagine ten pine twigs tied together: ten -> テン, and the tree 木 on the left holds them.