''Digitaria ischaemum'' is a species of

crabgrass ''Digitaria'' is a genus of plants in the grass family native to tropical and warm temperate regions but can occur in tropical, subtropical, and cooler temperate regions as well. Common names include crabgrass, finger-grass, and fonio. They are ...

known by the common names smooth crabgrass and small crabgrass. It is native to Europe and Asia, but it is known throughout much of the warm temperate world as an

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

and often a common roadside and garden weed. It is an annual grass producing an

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

with two or more narrow branches lined with tiny spikelets. It is easily confused with other members in the genus, particularly

southern crabgrass ''Digitaria ciliaris'' is a species of grass known by the common names southern crabgrass,''Digitaria ...

in California which differs by having spikelets of nearly twice the length. It may also be confused with

Bermuda Grass ''Cynodon dactylon'', commonly known as Bermuda grass, also known as couch grass in Australia and New Zealand, is a grass found worldwide. It is native to Europe, Africa, Australia and much of Asia. It has been introduced to the Americas. Contra ...

, but differs in being a much taller plant with a much longer inflorescence. It reproduces by seed. The leaves on this grass often form above the base of the plant, and it is usually singular, rarely forming large clumps.

Description

The flowers of smooth crabgrass grow in clusters of 2 to 6, forming spike-like shapes about 1½ to 4 inches long, arranged like fingers at the tips of branching stems. The flower

spikelet A spikelet, in botany, describes the typical arrangement of the inflorescences of grasses, sedges and some other monocots. Each spikelet has one or more florets. The spikelets are further grouped into panicles or spikes. The part of the sp ...

s are small, egg-shaped, and come in pairs along the stem, with one on a short stalk and the other on a longer one. Each spikelet has one fertile flower. The small bracts at the base of each spikelet are uneven in size, with one being almost invisible or absent and the other covered in short hairs. The bracts around the flowers are similarly sized, with one being hairy and the other having tiny pits. The flower styles and

stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s extend from the tip of the spikelet. The stem holding the spikes is green or purple, winged, and about 1 mm wide, with all the spikelets arranged on one side of the stem. The leaves of smooth crabgrass are arranged alternately, up to 4 inches long and ¼ inch wide, mostly flat and hairless except at the base. The leaf sheaths are open in the front, sometimes with a few long hairs near the top but mostly hairless, and they loosely wrap around the stem, often having a ridge along the back. The

ligule A ligule (from "strap", variant of ''lingula'', from ''lingua'' "tongue") is a thin outgrowth at the junction of leaf A leaf (: leaves) is a principal appendage of the plant stem, stem of a vascular plant, usually borne laterally above g ...

is white and very short, less than 1 mm. The stems (culms) are hairless, branch out from the base, and are mostly light green but may be purple near the base. The stems often spread outward and may root at the joints (nodes), which are hairless and can be green or purplish. As smooth crabgrass matures, its spikelets turn dark purple. The missing first

glume In botany, a glume is a bract (leaf-like structure) below a spikelet in the inflorescence (flower cluster) of grass Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family (biology), family of monocotyledonous flow ...

and the hairs on the second glume and lemma become more noticeable. The seeds are oval-shaped and dark brown to almost black.

Habitat

They grow in terrestrial regions and can be seen in

central Europe Central Europe is a geographical region of Europe between Eastern Europe, Eastern, Southern Europe, Southern, Western Europe, Western and Northern Europe, Northern Europe. Central Europe is known for its cultural diversity; however, countries in ...

and

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

Connecticut Connecticut ( ) is a U.S. state, state in the New England region of the Northeastern United States. It borders Rhode Island to the east, Massachusetts to the north, New York (state), New York to the west, and Long Island Sound to the south. ...

Maine Maine ( ) is a U.S. state, state in the New England region of the United States, and the northeasternmost state in the Contiguous United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Provinces and ...

Massachusetts Massachusetts ( ; ), officially the Commonwealth of Massachusetts, is a U.S. state, state in the New England region of the Northeastern United States. It borders the Atlantic Ocean and the Gulf of Maine to its east, Connecticut and Rhode ...

New Hampshire New Hampshire ( ) is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec t ...

Rhode Island Rhode Island ( ) is a state in the New England region of the Northeastern United States. It borders Connecticut to its west; Massachusetts to its north and east; and the Atlantic Ocean to its south via Rhode Island Sound and Block Is ...

Vermont Vermont () is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, New Hampshire to the east, New York (state), New York to the west, and the Provinces and territories of Ca ...

References

External links

Jepson Manual Treatment.

Grass Manual Treatment
*

ischaemum ''Ischaemum'' is a genus in the tribe Andropogoneae, belonging to the grass family, widespread in tropical and semitropical regions in many countries. Many species are known commonly as murainagrass. In 2022Shahid Nawaz(an agrostologist, The Bl ...

Grasses of Asia Grasses of Europe {{Panicoideae-stub