Short answers, pulled from the story.
Cyperaceae is a family of graminoid, monocotyledonous flowering plants commonly known as sedges. The family contains around 5,500 described species in about 90 genera, with Carex, the true sedges, being the largest genus at over 2,000 species.
Sedges typically have stems with triangular cross-sections and leaves arranged spirally in three ranks, while grasses have alternate leaves in two ranks. The mnemonic "sedges have edges" captures this distinction. Rushes are generally round, and grasses are often hollow with jointed nodes.
Sedges grow in almost all environments worldwide, with the greatest diversity concentrated in tropical Asia and tropical South America. Many species thrive in wetlands or in poor soils; sedge-dominated plant communities are called sedge meadows.
Well-known members include papyrus (Cyperus papyrus), from which the ancient writing material was made, and the water chestnut (Eleocharis dulcis). The family also includes cotton-grass (Eriophorum), sawgrass (Cladium), and nutsedge (Cyperus esculentus and Cyperus rotundus), which is both a cultivated crop called chufa and a common weed.
Sedge fossils have been identified from the Late Cretaceous, making the family tens of millions of years old. Researchers have found prominent sedges occurring at least as early as the Eocene epoch, indicating the family was already well-established long before modern ecosystems took shape.
Most sedges are wind-pollinated, like other members of the order Poales. Two exceptions are Cyperus niveus and Cyperus sphaerocephalus, which are insect-pollinated and have correspondingly more conspicuous flowers to attract pollinators.