Which type of plant typically has an even number of petals?

Monocots are a type of flowering plant that typically exhibit an even number of petals, commonly in multiples of three. This characteristic is due to their structural design, where the floral parts are organized in threes or multiples of three, reflecting the overall morphology of monocots. This includes plants such as lilies, orchids, and grasses.

In contrast, dicotyledons, another classification of flowering plants, generally tend to have petals in multiples of four or five, such as roses or sunflowers. Annuals and perennials refer to the lifespan of plants rather than their petal structure, with annuals completing their life cycle in one year and perennials living for multiple years. Thus, the unique petal arrangement of monocots is what makes them the correct choice in this question regarding even numbers.