Parts of a Grass Plant: A Glossary

Parts of a Grass Plant: A Glossary

How well do you know your grass anatomy? You can probably identify a blade, a root, and maybe even an awn (ouch!), but how about a culm, a rachilla, or a panicle?

Below are some of the grass-related words that you probably don’t use in everyday conversation:

  • Auricle: An earlike appendage at the junction of the blade and the sheath, not present in many species.
  • Axil: An angle formed between any two plant parts, but particularly between the culm and the upper surface of the leaf.
  • Collar: The outer surface of the leaf at the point where the sheath and blade join.
  • Corm: A short, swollen, bulblike stem that grows vertically underground. The corm stores nutrition in case of adverse conditions such as winter or drought.
  • Crown: The growing point near the base of the grass plant, where the shoot system joins the root system.
  • Culm: The stem.
  • Decumbent: Lying flat on the ground with the tip turned upward.
  • Dioecious: A species in which male (staminate) and female (pistillate) flowers are found on separate plants.
  • Endophyte: A plant, such as a fungus, living within the cells of another plant.
  • Floret: The flowering, seed-bearing part of a grass plant, located on the rachilla just above the glumes.
  • Glabrous: Hairless.
  • Glumes: The lowermost bracts or scales on the rachilla; the glumes contain no reproductive parts and serve a protective role.
  • Inflorescence: The flowering part of the plant; on grasses, this is what we commonly think of as the seed head.
  • Internodes: The part of the culm between two nodes.
  • Lemma: The lowermost of the two chaff-like bracts enclosing the floret. In some species, the lemma bears the pointed appendage known as the awn.
  • Ligule: A thin membrane or row of hairs inside the leaf blade where it joins the sheath. The ligule prevents water from running into the sheath.
  • Meristem: The area of cell division and growth. On a grass plant, this area is located at the junction of the leaf blade with the sheath.
  • Monecious: A species in which male (staminate) and female (pistillate) flowers are found on the same plant, but in different locations.
  • Node: A joint along the culm; leaves can grow at nodes.
  • Palea: The uppermost of the two chaff-like bracts enclosing the floret.
  • Panicle: An open, branching inflorescence with the lower branches longer than the upper ones and the flowers on stalks.
  • Pedicel: The stem supporting the spikelet.
  • Peduncle: The stem supporting the inflorescence.
  • Perfect: Of a flower, having both functional stamens and pistils.
  • Pubescence: A coating of hairs.
  • Raceme: A type of unbranched inflorescence in which the spikelets are connected to the stem by pedicels.
  • Rachilla: The central axis of a spikelet.
  • Rachis: The central axis of an inflorescence.
  • Rhizome: A runner or stem growing horizontally below the ground; a rhizome can produce new leaves and roots at nodes.
  • Sessile: Directly attached, versus on a stalk.
  • Sheath: The lower portion of a grass leaf; the part that wraps around the culm.
  • Spike: An unbranched inflorescence with stalkless flowers.
  • Spikelet: The unit that makes up the inflorescence, consisting of two glumes and one or more florets.
  • Stolon: A runner or stem growing horizontally along the surface of the ground; a stolon can produce new leaves and roots at nodes.
  • Tiller: A shoot. Tiller can also be used as a verb to describe the production of such shoots.
Parts of a Grass Plant: A Glossary

Helpful Resources

Forage and Pasture Plant Identification
Excellent resource with plenty of diagrams and illustrative photos.

Parts of Grass Spikelet
Includes a very helpful photo of a dissected spikelet.

By hsotr

Pulling from nearly 20 years of experience, Michelle Lindsey started Homestead on the Range to help Kansans and others around flyover country achieve an abundant country lifestyle. Michelle is the author of four country living books. She is also a serious student of history, specializing in Kansas, agriculture, and the American West. When not gardening or pursuing hobbies ranging from music to cooking to birdwatching, she can usually be found researching or writing about her many interests.