How to identify Smooth crabgrass (Digitaria ischaemum)

How to identify Smooth crabgrass (Digitaria ischaemum)

Smooth crabgrass, also known as Smooth Summergrass, Smooth Crab Grass, Small crabgrass

Smooth crabgrass is characterized by its prostrate, clump-forming growth habit, often rooting at its leaf nodes, which can make it difficult to remove. This summer annual exhibits a tenacious capacity to establish and spread throughout the warmer months. Its flat, green blades and compressed stem joints are distinctive features aiding in its identification. As a prolific seeder, smooth crabgrass takes advantage of the warming soils of late winter to early spring for germination, dying back with the onset of frost. The plant typically displays a height of up to 6 inches (15 cm), adapting well to garden and lawn environments where it is commonly found.

Lifespan: Annual, Biennial

Plant Type: Grass

Leaf Type: Deciduous

Quickly Identify Smooth crabgrass

Prostrate, clump-forming growth habit with rooting leaf nodes.

Small, egg-shaped spikelets in flower clusters on stem ends.

Distinct color evolution of fruit from green to dark brown/black.

Flat leaves up to 4 inches (10 cm) long with smooth texture.

Slender stems ranging from light green to purple, occasionally flattened.

Detailed Traits of Smooth crabgrass

Leaf Features

The leaves of smooth crabgrass are flat, reaching up to 4 inches (10 cm) in length and 1/4 inch (0.6 cm) in width. They are green and feature a smooth texture with fine hairs at the base of the sheath. The sheaths are ridged, open at the front, and occasionally adorned with a few long hairs, contributing to the plant's distinctive appearance.

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Flower Features

The flowers of smooth crabgrass are characterized by their clusters at the end of flowering stems, featuring small, egg-shaped spikelets that generally appear in pairs along the stem. Each spikelet measures about 1/8 inch (3 mm) in length. The flowers are typically greenish or purplish in color, blending well with the plant's foliage. They exhibit a tight, compact arrangement, ensuring a dense cluster appearance. These flowers bloom from mid-summer to early fall, emitting no noticeable scent.

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Stem Features

The stems of smooth crabgrass are slender and can vary in color from light green to occasionally purple near the base. These stems are typically surrounded by sheaths in the lower regions, offering protection. The outer texture is smooth and may feel slightly wiry. Stems generally reach a modest thickness and display a sparse branching pattern. Some may exhibit a slightly flattened appearance. The sturdy structure facilitates identification, especially when observing the color gradation and sheath coverage.

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Fruit Features

The fruit of smooth crabgrass is a caryopsis, commonly recognized as a grain. As the plant matures, the fruit exhibits a distinctive transformation in coloration, evolving from an initial green to a rich brown or purplish hue. Upon full maturity, the grain achieves a deep, dark brown to black tone. The fruits are nestled within spikelets and embody an oval shape, which is characteristic of this species. These seeds are relatively small in size, offering a firm texture to the touch. The contrast in coloration from the plant's earlier stages to the mature fruit is noteworthy and can assist in identification.

Learn About the Fruit Glossary

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Smooth crabgrass and Their Similar Plants

Hairy crabgrass vs. Smooth crabgrass: What's The Difference?

Hairy crabgrass (Digitaria sanguinalis) is a plant species that is known worldwide as a common weed. In certain circumstances, hairy crabgrass is used as animal fodder. This grass species is extremely hardy and almost always requires a detailed control plan, as any chemicals used to eliminate it may also harm surrounding grasses.

Southern crabgrass vs. Smooth crabgrass: What's The Difference?

Southern crabgrass (Digitaria ciliaris) is an aggressive grass that likely originated in Asia but is now found throughout the world. It is hardy and adaptable to different soil types, and is often considered an invasive weed, especially in North America and China. If not in an area that threatens crops, however, southern crabgrass can be utilized to stabilize and protect the soil.

Asian crabgrass vs. Smooth crabgrass: What's The Difference?

Asian crabgrass is a common weed in lawns and gardens. It has economic value as a forage crop for livestock and is an important food source for birds and insects.

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Key Facts About Smooth crabgrass

Attributes of Smooth crabgrass

Plant Height

15 cm to 46 cm

Spread

15 cm to 45 cm

Leaf Color

Green

Flower Size

2.5 cm

Flower Color

Green

Yellow

Purple

Brown

Leaf type

Deciduous

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Scientific Classification of Smooth crabgrass

Phylum

Vascular plants

Class

Monocotyledons

Order

Grasses, sedges and allies

Family

Grass

Genus

Crabgrasses

Species

Smooth crabgrass (Digitaria ischaemum)

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Distribution Map of Smooth crabgrass

Smooth crabgrass is a widespread plant, native to a broad swathe of Europe and Asia, spanning from the Mediterranean region to East Asia. Its natural range stretches from the subtropics to temperate zones. Furthermore, smooth crabgrass has been introduced to various continents including North America, South America, Australia, and parts of northern Europe, where it has established itself in diverse climates and environments.

Native

Cultivated

Invasive

Potentially invasive

Exotic

No species reported

Learn More About the Smooth crabgrass

A Comprehensive Guide to Smooth crabgrass How to Grow and Care for Smooth crabgrass