COMMON NAME

Hairy jointgrass
Small carpgrass


FULL SCIENTIFIC NAME

Arthraxon hispidus (Thunb.) Makino


FAMILY NAME COMMON

Grass family


FAMILY SCIENTIFIC NAME

Arthraxon hispidus


IMAGES


Close-up of leaves and stem

Habit

Incursion

Roots

Clasping leaf bases

Incursion

Close-up of infructescence

NOMENCLATURE/SYNONYMS

Synonyms: Phalaris hispida Thunb.


DESCRIPTION

Botanical Glossary

Arthraxon hispidus is a low-growing annual grass that grows to 0.5 m (1.5 ft.) tall. The ovate to lanceolate leaf blades are 2-7 cm (0.75-2.75 in.) in length and 5-15 mm (0.2-0.6 in.) wide. There are hairs along the margins of the leaf blades. The cordate bases of the leaves encircle the stem. The flowers are borne on few to several digitate spikes that measure 2-4 cm (0.75-3 in.) long. The spikelets measure 3-5 mm (0.1-0.2 in.) long. The lower glume has 4-15 rough veins, and the upper glume has 3-5 inconspicuous veins. Sterile lemmas have inconspicuous venation, while the fertile lemmas have 1 vein. The flowers appear from September to October. The seeds are slender and yellowish in color, measuring 4 mm (0.2 in.) long. Page References Fernald 230, Gleason & Cronquist 817, Holmgren 773, Magee & Ahles 190. See reference section below for full citations.


SIMILAR SPECIES

Dicanthelium clandestinum (L.) Gould (Deertongue grass) Deertongue grass can be distinguished from A. hispidus by the fact that it has a panicled inflorescence, whereas A. hispidus has fairly tight spiked inflorescences. Deertongue grass is slightly larger, covered with stiff hairs, and its leaves are generally longer and more lanceolate in shape. Lastly, Deertongue grass can usually be found in drier sites than A. hispidus.


REPRODUCTIVE/DISPERSAL MECHANISMS

Arthraxon hispidus reproduces by seeds that are dispersed mechanically, and probably spread further by moving water.


DISTRIBUTION

Arthraxon hispidus is native to Japan and eastern Asia, from Korea to Indochina. It has been reported in the eastern U.S. from Massachusetts to Florida and west from Illinois to Texas. It has also been found in Oregon. Its most substantial populations in the U.S. are in the southeastern states. In New England, it appears to be limited to Massachusetts and Connecticut; however, the last report of this plant from Massachusetts dates from 1973. Further investigation will be necessary to determine whether or not this Massachusetts population has been extirpated.


HISTORY OF INTRODUCTION IN NEW ENGLAND

It is unclear exactly how and when Arthraxon hispidus first arrived in North America. The widely spread, patchy nature of its distribution points to multiple introductions. Early records from Missouri and coastal Virginia indicate that Arthraxon hispidus was present in the U.S. by the early 1930s. Fernald (1950) described its distribution as "Fla to Ark, n. to NY." He also described it as "naturalized" and "rapidly spreading." Exactly when it arrived in New England is unclear, though it was most likely after its southern populations were established. Seymour (1969) did not record its presence in the Flora of New England. Since then, populations of Arthraxon hispidus have been confirmed in both Massachusetts and Connecticut.


HABITATS IN NEW ENGLAND

Edge, Floodplain Forest, Lake or Pond, Open Disturbed Area, Pasture, River or Stream, Wet Meadow

Arthraxon hispidus prefers sunny moist habitats. It is often found in moist pastures and fields, floodplain forests, on stream banks and along shorelines.


THREATS

Arthraxon hispidus can form dense stands, particularly along shorelines, that may threaten native vegetation.


DOCUMENTATION NEEDS

Documentation required: Herbarium specimen or mounted snippet of the plant in flower or fruit.
Best time for documentation: Late summer, fall.


ADDITIONAL INFORMATION

Integrated Taxonomic Information System
Taxonomic information about the species

The PLANTS Database, Version 3.1. (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
General information and map

Virginia Tech Department of Plant Pathology, Physiology and Weed Science
Images and brief description

USGS-Southern Wetland Flora
Images and brief description


REFERENCES

Fernald, M.L. 1950. Gray's Manual of Botany 8th ed. American Book Co., Boston.

Gleason, H.A. and A.C. Cronquist.  1991.  Manual of Vascular Plants of the Northeastern United States and Adjacent Canada. 2nd ed.  New York Botanical Garden, Bronx, New York.

Holmgren ,N.H. 1998. Illustrated Companion to Gleason and Cronquist's Manual.  New York Botanical Garden, Bronx, New York.

Magee, D.W and H.E. Ahles. 1999.  Flora of the Northeast. University of Massachusetts Press, Amherst.

USDA, NRCS.  2001.  The PLANTS Database, Version 3.1. (http://plants.usda.gov).  National Plant Data Center, Baton Rouge, LA 70874-4490 USA.