Which of these plants is not botanically classified as a member of the grass family?

Papyrus, writing material of ancient times and also the plant from which it was derived, "Cyperus Papyrus" (family "Cyperaceae"), is also called "paper plant". Papyrus is a grasslike aquatic plant -but it is not grass- that has woody, bluntly triangular stems and grows up to 4.6 m (about 15 feet) high in quietly flowing water up to 90 cm (3 feet) deep. The triangular stem can grow to a width of as much as 6 cm. The papyrus plant is often used as a pool ornamental in warm areas or in conservatories. The dwarf papyrus ("Cyperus Isocladus", also known as "Cyperus Papyrus Nanus"), up to 60 cm tall, is sometimes potted and grown indoors.

The ancient Egyptians used the stem of the papyrus plant to make sails, cloth, mats, cords, and, above all, paper. Paper made from papyrus was the chief writing material in ancient Egypt, was adopted by the Greeks, and was used extensively in the Roman Empire. It was used not only for the production of books (in roll or scroll form) but also for correspondence and legal documents.

Papyrus was cultivated and used for writing material until the time when the growing manufacture of paper from other plant fibers rendered papyrus unnecessary. By the 3rd century AD, papyrus had already begun to be replaced in Europe by the less-expensive vellum, or parchment, but the use of papyrus for books and documents persisted sporadically until about the 12th century AD.