106 higher rate of water movement to tracheary elements than in parenchyma cells. Vessel members: scalariform perforation plate, simple perforation plate two general types of pits, simple pit, bordered pit. Gymosperm division gnetophyta have evolved vessels: ex) ephedra (in this division, only gymosperm to evolve vessels is in this division. R4: rate at which water moves through cell (hydrolic conductance) is related to radius by r4. In simple pits, the pull of water can move an air bubble into the adjacent cell may inactivate many cells: harder to pull through with bordered pits (even some unique innovations that prevent air bubble movement) Anthocerophyta hornworts (thalloid) very thin, no water conducting cells in living plants or fossil record. Hepatophyta liverworts (thalloid) have water conducting cells. Bryophyta mosses (leafy) have water conducting cells. The water conducting cells secondary wall with polyphenolic compounds lignin-like, offer resistance to decay. Vessel members shorter and wider: evolved/derived from tracheids.