twice-pinnate

Thân thiện

A botanist examines a twice-pinnate leaf in a field guide.

Definition

Adjective (Botany): - Describing a compound leaf where the primary leaf axis (rachis) bears secondary axes (pinnae), and leaflets are arranged along these secondary axes. This structure means the leaf is divided two times: first into pinnae, and then each pinna into leaflets.

Usage

• This term is used specifically in botany to describe the architecture of certain leaves, particularly common in ferns and some flowering plants like acacias or mimosas.
• It is a technical descriptor. The simpler, more common term for this structure is "bipinnate."

Examples

Advanced Usage

• Degree of Division: Leaves can be described with greater specificity: "thrice-pinnate" (tripinnate) or "decompound" for multiple divisions.
• Context: The term is primarily used in formal botanical descriptions, field guides, and scientific literature.

Variants and Related Words

• Bipinnate (adj.): The most common synonym for "twice-pinnate."
• Pinna (n.): A primary division of a pinnate leaf.
• Pinnule (n.): A leaflet of a bipinnate leaf; the ultimate division on a twice-pinnate structure.
• Pinnate (adj.): The broader category, describing a feather-like leaf with leaflets arranged along a central axis.

Synonyms

• Bipinnate

Antonyms

• Simple (referring to a leaf with a single, undivided blade).
• Palmate (referring to a leaf with leaflets radiating from a single point, like fingers from a palm).

Học thuật

Noun

1. a pinnate leaf having two pairs of leaflets

Từ đồng nghĩa

• bijugate leaf
• bijugous leaf