Digitaria filiformis

Digitaria filiformis
Photo taken by Kevin Robertson
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta - Flowering plants
Class:	Liliopsida – Monocotyledons
Order:	Cyperales
Family:	Poaceae ⁄ Gramineae
Genus:	Digitaria
Species:	D. filiformis
Binomial name
Digitaria filiformis (L.) Koeler
Natural range of Digitaria filiformis from USDA NRCS Plants Database.

Common name: slender crabgrass

Taxonomic notes

Synonym: Syntherisma filiformis (L.) Nash; Panicum filiforme L.

Description

Generally, for the Digitaria genus, they are "annuals; internodes glabrous. Leaves cauline; blade margins cartilaginous, scaberulous; sheath margins usually scarious; ligules membranous. Racemes racemose, ascending; rachis usually winged, scaberulous. Spikelets plano-convex, ellipsoid, acute. First glume usually absent, 2nd glume villous on nerves and margins, acute, sterile lemma 5-7 nerved, acute; fertile lemma and palea nerveless, cartilaginous, glabrous, acute; fertile lemma margins flat, hyaline. Grain whitish to brownish, ellipsoid. These plants are out worst field and gardens weeds." - Radford et al 1964.

Specifically, for D. filiformis species, they are "cespitose annual; culms 3-12 dm tall, nodes glabrous. Blades to 15 cm long, 2-4 mm wide, papillose-hirsute and scaberulous above, glabrous or occasionally pilose to hirsute beneath; sheaths papillose-hirsute; ligules erose to lacerate, 0.5-1 mm long. Racemes 2-7, ascending, 3-12 cm long; rachis trigonous, wingless, scaberulous. Spikelets 1.8-2.5 mm long; pedicels scaberulous, -.5-3 mm long. Second glume 5- nerved, 1.2-1.5 mm long, sterile lemma margins ciliate, 1.8-2 mm long; fertile lemma and palea purple, papillose lined, 1.8-2 mm long. Grain 1-1.2 mm long, whitish to brownish, ellipsoid." - Radford et al 1964.

Ecology

Habitat

In the Coastal Plain region, Digitaria filiformis is found in pine-oak, oak-palmetto and open longleaf pine-wiregrass woodlands along with turkey-oak sand ridges, banks of ditches in saltmarshes, and transition zones between longleaf pine, turkey oak sand ridge and pine flatwoods (FSU Herbarium). Occasionally has been found in mesic flatwoods in Hillsborough County, Florida (Myers et al. 2003). It has been vouchered in an outcrop habitat on Panola Mountain located within Henry-Rockdale county line, southeast of Atlanta, Georgia (Bostick 1971). D.filiformis also occurs in the Kansas-Nebraska Drift Loess Hills characterized by divides with moderately steep slopes and silt loams and silty clay loam soils occasionally broken by bedrock outcrops (Watt et al. 1967).

Human impacted areas in the Coastal Plain region that have documented populations of D. filiformis include fallow and open weedy park fields, roadsides, powerline corridors, clobbered longleaf pine forest and cleared sand pine and pine flatwood communities (FSU Herbarium).

In the Coastal Plain region it has been documented as occurring on “upland, sandhill areas on droughty, infertile entisols and ultisols with loamy sand to sandy loam surface horizons” (Archer et al. 2007). It has also been recorded to occur in silty soils (FSU Herbarium). Light levels have observed to be partially shaded (FSU Herbarium).

Species found associated with D. filiformis in the Coastal Plain region are Liatris, Pityopsis, Aristida stricta, Aristida purpurascens, Andropogon gerardii, Pteridium aquilinum, Nolina atopocarpa, Hedeoma graveolens, Hedyotis procumbens, Angelica dentata, Rhynchospora globularis, Solidago and Eragrostis (FSU Herbarium).

Phenology

Flowering and fruiting have been observed in June, August, September, October and November (FSU Herbarium).

Seed dispersal

According to Kay Kirkman, a plant ecologist, this species disperses by gravity.

Fire ecology

This species has been found in habitat types that are maintained by fire, which implies some level of fire tolerance (FSU Herbarium).

Use by animals

White-tailed deer stomach contents, in Kansas-Nebraska Drift Loess Hills, included Digitaria filiformis year-round (Watt et al. 1967).

Photo Gallery

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  Digitaria filiformis

  Photo by Kevin Robertson

References and notes

Archer, J. K., D. L. Miller, et al. (2007). "Changes in understory vegetation and soil characteristics following silvicultural activities in a southeastern mixed pine forest." Journal of the Torrey Botanical Society 134: 489-504.

Bostick, P. E. (1971). "Vascular Plants of Panola Mountian, Georgia " Castanea 46(3): 194-209.

Florida State University Robert K. Godfrey Herbarium database. URL: http://herbarium.bio.fsu.edu. Last accessed: June 2014. Collectors: Loran C. Anderson, H. E. Ahles, Tom Barnes, Michael B. Brooks, Robert W. Simons, Dianna Hall, R. Kral, R. K. Godfrey, Sidney McDaniel, R. A. Norris, H. R. Reed, Cecil R. Slaughter, Frankie Snow, A. E. Redford, C. Simon, A. A. Eaton, Robert L. Lazor, Bruce Hansen, JoAnn Hansen, W. A. Silveus, A. F. Clewell, Robert Blaisdell, O. Lakela, George R. Cooley, Richard J. Eaton, Daniel B. Ward, Paul O. Schallert, and A. H. Curtiss. States and Counties: Florida: Bay, Brevard, Clay, Dixie, Duval, Escambia, Franklin, Flagler, Gadsden, Hillsborough, Jackson, Jefferson, Leon, Levy, Liberty, Madison, Nassau, Osceola, Putnam, Sarasota, St. Johns, Taylor, Wakulla, and Washington. Georgia: Camden, Coffee, and Grady. Mississippi: Pearl River and Oktibbeha. North Carolina: Alexander. South Carolina: Hampton. Virginia: Pulaski. Other Countries: Switzerland.

Myers, J. H., and Richard P. Wunderlin (2003). "Vascular Flora of Little Manatee River State Park, Hillsborough County, Florida." Castanea 68(1): 56-74.

Radford, Albert E., Harry E. Ahles, and C. Ritchie Bell. Manual of the Vascular Flora of the Carolinas. 1964, 1968. The University of North Carolina Press. 138. Print.

Watt, P. G., G.L. Miller, and R.J. Robel (1967). "Food Habits of White-tailed Deer in Northeastern Kansas." Transactions of the Kansas Academy of Science 70(2): 223-240.