Grass Leaves (Sheath, Collar, Ligule, Blade, Inrolled)

Grass leaves have three main parts – a sheath that wraps around the stem, a collar that connects the sheath to the leaf blade, and the leaf blade itself.

Bolander’s Reedgrass

Photo courtesy Zoya Akulova-Barlow

Each grass leaf begins from the base of the stem or from a stem node. The leaf wraps around the stem, forming a sheath. The new sheath is underneath older leaf sheaths, right next to the stem.

Alkali Cord Grass (Spartina gracilis) Photo by Steve Matson

Leaf sheaths may be open, with their edges not connecting, or closed forming a complete tube around the stem.

A mostly closed sheath:

California Brome (Bromus carinatus)

Photo by Keir Morse

An open sheath:

Reed Fescus (Festuca arundianacea)
Photo by Keir Morse

Cells at the top of the sheath form a collar, often easy to spot because it has a different color. The collar has specialized meristem cells. Meristem cells divide, growing a leaf blade above the collar. This means that the blade tip is the oldest part of a blade, and its base the newest. Other collar cells are rigid, providing support for the blade.

A ligule grows at the junction of the sheath and blade – an extension of the sheath. Ligules can be membranous, hairy, or both. They can be so short they’re hard to see, or up to ¾” long. The ligule provides a seal between the sheath and stem, protecting the stem below from insects, rain or dirt.

Annual Beard Grass (Polypogon monspeliensis) – photo by Keir Morse

Leaf blades extend out from the stem, starting at the collar. They can be flat, folded or inrolled (with the edges curling upwards and sometimes joining to form a straw-like shape. Their edges can be wavy and/or hairy. Try running your finger along the edge, in both directions, to test it for roughness. Leaf tips can be pointed, blunt, or boat-shaped, like the tip of a canoe.

Silver Hair Grass (Aira caryophyllea)
Photo by Wilde Legard

Orchard Grass (Dactylis glomerata)
Photo by Wilde Legard

Some grass-like plants have a leaf sheath but no blade at all.

Spreading Rush (Juncus patens)

Here, leaf sheaths start brown, turn pale, and then end without producing a blade.

Grass leaf blades do the majority of photosynthesis. They have parallel veins. They can continue growing if eaten or damaged, as long as the meristem cells in the collar haven’t been disturbed.

Vegetative grass parts develop differently in each species, varying in shape, size and color. For instance, a leaf sheath may be open or closed. A ligule may be short or long, membranous or hairy. Blades may be narrow or wide, short or long, pointed or round tipped.

Spend time with your grass – there’s lots to learn about it.

Want more?

· Jean Turner’s excellent article on Grass Identification.

· Leaf Formation by Oregon State University

Corrections/Comments: bruce@PlantID.net