Practice question

Gnetophytes comprising three disparate genera Gnetum tropical lianas, Ephedra desert shrubs, Welwitschia Namib Desert two-leaf plant exhibit several angiosperm-like features uncommon other gymnosperms: presence true xylem vessel elements with open perforation plates simple foraminate allowing efficient conduction, broad net-veined leaves in Gnetum resembling dicots, double fertilization event producing two diploid fertilizations but second product aborting without persistent triploid endosperm, and flower-like compound strobili with perianth-like bracts. Swimming sperm absent non-motile, seeds still formed on bracts without ovary, cones present unisexual. Vessels enhance conductivity supporting warm arid or tropical habitats with high evaporative demand.