phylloclade

A phylloclade is a flattened stem that functions as a leaf, with true leaves typically reduced or absent. It is a type of cladode whose primary role is photosynthesis, and in many species the stem’s green surface takes over the leaf’s functions.

Structurally, phylloclades arise from a shoot axis and are usually green and photosynthetic. They often carry stomata on their outer surface and have vascular tissue connected to the main stem, sometimes with a prominent central vascular strand. The true leaves, when present, are usually reduced to tiny scales or are vestigial.

Phylloclades are common in plants adapted to low-leaf or arid conditions, where reducing leaf area helps minimize water loss while preserving photosynthetic capacity. In some genera, such as Ruscus (butcher’s broom) and Phyllocladus (celery pines), the phylloclades are the dominant photosynthetic organs, and the plant’s true leaves are greatly reduced or not visible.

Taxonomy and notes: the term phylloclade is sometimes used interchangeably with cladode, though some authorities reserve phylloclade for flattened stems that mimic leaves. Phylloclades are distinct from phyllodes, which are leaf-like petioles found in other plant groups. These structures illustrate the variety of plant strategies for balancing photosynthesis with water conservation.