Definition of PLACOID. : of, relating to, or being a scale of dermal origin with an enamel-tipped spine characteristic of the elasmobranchs. ADVERTISEMENT.Greek plak-, plax flat surface.First Known Use: 1842.efinition of PLACOID. : of, relating to, or being a scale of dermal origin with an enamel-tipped spine characteristic of the elasmobranchs. ADVERTISEMENT. Greek plak-, plax flat surface. First Known Use: 1842.
A tree pruner is a class 1 lever. The fulcrum is where the two blades cross, and the load is what you are cutting. The effort is applied to the two handles.
How to Prune a Tree. A tree may need pruning for a variety of reasons: Â· to remove diseased or storm-damaged branchesÂ· to thin the crown to permit new growth and better air circulationÂ· to reduce the height of a treeÂ· to remove obstructing lower branchesÂ· to shape a tree for design purposes.