Practice question

Gymnosperm secondary xylem traditionally called softwood lightweight composed more than ninety percent tracheids, elongated imperforate elements with tapered overlapping ends and bordered pits featuring torus-margo membrane in Pinaceae pines firs providing both mechanical support and water conduction without vessels, preventing spread embolism. Absence vessels simple perforation plates reduces conductivity but improves safety against cavitation freezing in boreal habitats cold. Xylem parenchyma sparse living cells, resin canals present some groups. Tracheids plus rays form dominant wood cylinder accounting mechanical strength. This tracheid-only system distinguishes typical gymnosperms from angiosperm hardwoods which additionally contain wide vessels, fibers and abundant axial parenchyma.