What tree genus includes apples and crabapples?

The tree genus that includes apples and crabapples is Malus.

Malus is a genus in the rose family, Rosaceae. It includes the domesticated orchard apple, Malus domestica, along with wild apples and numerous crabapple species and hybrids. Members of the genus are generally small deciduous trees or shrubs native to temperate parts of the Northern Hemisphere.

Apple and crabapple distinctions are useful horticulturally but do not mark a clean split between unrelated plants. Crabapples are Malus species or cultivars that typically produce smaller, more acidic fruits. Their spring flowers and persistent autumn fruit also make them popular ornamental trees. Some crabapples are planted in orchards as pollinizers because their flowers provide compatible pollen for cultivated apples.

Malus is easily confused with Pyrus, the pear genus, or Prunus, which includes cherries, plums, peaches and apricots. Morus is the mulberry genus. Apple seeds contain cyanogenic compounds, so they are not normally eaten in quantity, while crabapple fruits are often cooked into jellies because they are rich in pectin and naturally tart.