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.
When To Hire an Arborist. 1  TREE PRUNING-Arborists can determine what type of pruning is best for the individual tree to maintain its health and improve its appearance and safety. 2  Also, if pruning requires a ladder and a chainsaw, hire a professional.he title ARBORIST refers to a person who has gained the technical competence to correctly and efficiently care for trees and other woody plants.