A leaf without a petiole is referred to as what?

A leaf without a petiole is referred to as "sessile." This term specifically describes leaves that are directly attached to the stem without a stalk, which is what a petiole is. In botany, understanding the structure of leaves, including whether they possess a petiole, is essential for identification and classification of plant species. Sessile leaves can often create a different growth form and are an adaptation that can influence how plants interact with their environment, such as maximizing sunlight capture or modifying water retention.

The other terms, while related to plant characteristics, refer to different concepts. "Deciduous" describes trees or plants that lose their leaves seasonally. "Green" refers to the color of the leaves, which is primarily due to the presence of chlorophyll. "Stipulate" pertains to the presence of stipules, which are small leaf-like structures at the base of the petiole, and does not relate directly to the petiole's presence or absence. Therefore, "sessile" is the precise term for leaves lacking a petiole.