Eragrostis spp.

Lovegrass, stinkgrass, candygrass,

skunkgrass, snake-grass, pungent

meadowgrass.

Poaceae                                                     

       Eragrostis is the largest genus in the family Poaceae. The 350 species that have been described constitute more than a quarter of the family (Van den Borre and Watson 1994). At least 25 species of Eragrostis are present in Eastern North America today. Some members of the genus are native to this region, while others derive from the Old World (Hitchcock and Chase 1971; Yatskievych and Turner 1990). The diverse possible origins of Eragrostis in archaeological assemblages creates an interpretive dilemma: identified only to the generic level, an Eragrostis grain may signify either the prehistoric use of grasses or the presence of intrusive plant material. In this entry, I provide preliminary information on some selected Eragrostis species as a starting point for further research on archaeobotanically visible differences between Eragrostis species.


Description

       Grains are separated from the floret quite easily among Eragrostis annuals, but less so among perennial species (Davidse pers. comm. 1996). Once disarticulated, seeds of Eragrostis are notable for their extremely small size: 0.5-0.6 mm. Eragrostis seeds will not be retained in flotation samples for which a 0.7 mm or larger mesh was used. The appearance of Eragrostis from samples using 0.5 mm mesh is also doubtful. Use of a finer mesh to attempt recovery of Eragrostis caryopses might, under some field conditions, cause practical difficulties and damage to other archaeobotanical material. Detection of any Eragrostis in the archaeobotanical record is therefore highly problematic. If specimens are recovered, they should ideally be identified to the species level in order to assess their significance.

       Most Eragrostis caryopses are similar in gross morphology and configuration of textural and surface attributes; they are roughly ovate in form, and have slender longitudinal grooves truncated in some cases by lacy horizontal ridges. Embryos are tucked under the base of the caryopsis. The hilum is broad and flat except for its central ridge. Differences between species are subjective: caryopses may vary according to the size and proportion, and to the color and prominence of certain features. In the following section, I give preliminary descriptive information for three Eragrostis species. The first two descriptions (E. curvula and E. pectinacea) are based on single-plant samples of six specimens each, obtained from the Missouri Botanical Garden. The third (E. cilianensis) is based on a larger sample from plants collected at Portage des Sioux, north of Saint Louis.

       Eragrostis curvula (Figure 2) is a perennial native to the Old World (Hitchcock and Chase 1971; Steyermark 1963; Yatskievych and Turner 1990). Its seeds are resinous gold in color. Caryopsis length is 1.3-1.4 mm, width is 0.62-0.74 mm, and thickness is 0.40-0.46 mm. The dorsal area is flattened with a very slight depression across the middle. Lateral areas are quite steep-sided. The ventral side shows a slightly raised hilum area, which is squarish and darker than the rest of the caryopsis. The color of the hilum area ranges from dark grey to only slightly greyish with a red caryopsis. The ridge in front of the hilum is slightly lighter than the rest of the hilum. Longitudinal grooves are slightly irregular. No horizontal truncations are evident under the light microscope.

       Eragrostis pectinacea (Figure 3) is an annual native to the New World (Hitchcock and Chase 1971; Steyermark 1963; Yatskievych and Turner 1990). Its seeds are pale resinous gold in color. Caryopsis length is 0.64-0.86 mm, width is 0.28-0.36 mm, and thickness is 0.40-0.45 mm. The dorsal surface is rounded. Lateral areas are flat, and some parts are slightly depressed. On the ventral face, the base of the caryopsis is darker and greyish. The hilum area is flattened (except for its mid-line ridge) and only slightly darker than the rest of the caryopsis. Longitudinal grooves are straighter than those on E. curvula. A few horizontal truncations are visible under the light microscope at 50X: each groove appears to be truncated in three or four places. Grooves and truncations are less pronounced on lateral surfaces.

       Eragrostis cilianensis (Figures 4-6) is an annual native to the Old World (Hitchcock and Chase 1971; Steyermark 1963; Yatskievych and Turner 1990). Its seeds are resinous gold in color. Caryopsis length is 0.80-0.86 mm, width is 0.38-0.40 mm, and thickness is 0.48-0.50 mm. The dorsal face (Figure 4)is rounded, and has a shiny surface despite significant grooves. Lateral areas (Figure 5) are flat, and slightly rounded at the edges. The ventral face (Figure 6) is quite rounded. The hilum area is strongly indented, but has a pronounced central ridge. There is no significant color difference between the hilum and the rest of the caryopsis. Longitudinal grooves are regular and pronounced in most areas. Few horizontal truncations are evident under the light microscope (50X), but they are readily apparent in SEM micrographs.

Taxonomic issues

       Preliminary observation of selected Eragrostis species suggests that bases for inter-specific differentiation exist, but that objective criteria will require much more research. Some criteria reported above, such as color, will not be observable on carbonized specimens. Furthermore, the large number of species within the genus will impede attempts  to find solid, pan-regional criteria to identify particular species of Eragrostis from archaeobotanical remains. Rather, identification should be pursued within the framework of a restricted, very local list of possible species. Systematic recording of traits for all of these species will, however, be necessary. Preliminary efforts toward one such local list are presented in Table 1.

Table 1. Preliminary compilation of seed attributes for selected Eragrostis species found in Missouri.*

Species

Origin (Old World or New World)

Caryopsis length

Shape of Caryopsis

E. capillaries

Old World

0.6  mm

subglobose to oblong

E. pilosa

Old World

0.6-0.8

subglobose

E. eliottii

Old World

0.5-0.7

oblong

E. curvula

Old World

1.3-1.4

subglobose

E. cilianensis

Old World

0.80-0.86

subglobose

E. frankii

New World

0.5

oblong to quadrate

E. hirsuta

New World

0.5-0.7

oblong to papilose

E. ciliaris

New World

0.5-0.6

narrow ellipsoid

E. pectinacea

New World

0.65-0.85

subglubose

 

Archaeological Distribution
       To date, there are few if any references to Eragrostis in published archaeobotanical reports on sites in Eastern North America. After seeing modern specimens, a few researchers have retrospectively confirmed the presence of Eragrostis in archaeobotanical assemblages from various parts of the United States. These seeds were originally reported as Poaceae or as unidentified.

The Modern Plant and Its Distribution
       Twelve species of Eragrostis are considered native to the Eastern Woodlands: E. capillaris, E. ciliaris, E. frankii, E. hirsuta, E. intermedia, E. tephrosanthos, E. trichodes, E. hypnoides, E. glomerata, E. pectinacea, E. reptans, and E. spectabilis (Hitchcock and Chase 1971; Steyermark 1963; Yatskievych and Turner 1990). Archaeobotanical specimens of these species cannot necessarily be regarded as intrusive in Eastern Woodlands archaeological contexts. They may have been gathered as grains. In particular, E. pectinacea appears on several lists of edible plants in the region (Kunkel 1984; Zawacki and Hausfater 1969).

 

       At least 14 Eragrostis species growing wild in the Eastern Woodlands today are known to be of Old World origin. They include E. bahiensis, E. curvula, E. diffusa, E. multicaulis, E. lehmannia, E. pilosa, E. stenophylla, E. uniloides, E. cilianensis, E. barrelieri, E. curtipedicellata, E. elliotii, and E. secundiflora (Hitchcock and Chase 1971; Steyermark 1963; Yatskievych and Turner 1990). The occurrence of any of these species in a pre-contact archaeological assemblage should be regarded as intrusive.

       Present-day Eragrostis plants show great diversity in size and form (Figure 1). Average heights of species range from 10 cm to more than 50 cm. Most species in the Eastern Woodlands today occupy fields, waste areas, and one of the following environments: roadsides/railways, marshes, sandy shores and stream banks, open woodland, or piedmont (Hitchcock and Chase 1971; Radford et al. 1964; Yatskievych and Turner 1990). Species of Old World origin are often attributed to the wetter environments listed above, whereas native species are listed in conjunction with drier, sandy environments (Gleason and Cronquist 1992; Steyermerk 1963; Yatskievych and Turner 1990). Additional species grow in more arid areas of the western United States.

 

Discussion

      Throughout the world, Eragrostis species have been valuable sources of grain. Many Old World Eragrostis species are native to the kreb or kasha complex of edible wild grasses that grow in a belt of savanna vegetation south of the Sahara, and are harvested from Nigeria to Sudan (Harlan 1989). One member of the genus, E. tef, is an Ethiopian domesticate and today is farmed on a greater land area than any other crop in Ethiopia, where it is one of the national crops (Harlan 1989). Other Eragrostis species have been harvested wild with other kreb grasses for millennia, and are still of economic importance to Sahelian people (Harlan 1993). Eragrostis species are also harvested in other parts of sub-Saharan Africa in times of scarcity (national Research Council 1996).

       Outside of Africa, seeds of various Eragrostis species have been harvested from the wild either regularly or as a famine food in western or southern Asia, Australia, and the western and southern United States (Harris and Hillman 1989 (passim); Kunkel 1984). Compendia of edible foods in Eastern North America note that the seeds of Eragrostis pectinacea may be ground into flour and eaten (Kunkel 1984; Zawacki and Hausfater 1969). It is not clear, however, whether these listings derive from first-hand ethnographic observation of food preparation by Native Americans, or from experimentation by explorers. The continued use of Eragrostis throughout the world attests to the subsistence potential of this cereal, which may have been used by the prehistoric inhabitants of the Eastern Woodlands.

References

Gleason, H. A., and A. Cronquist

    1992   Manual of the Vascular Plants of Northeastern United States and Adjacent Canada.
            New York Botanical Garden, Bronx.

Harlan, J. R.

    1993   The Tropical African Cereals.  In The Archaeology of Africa: Food, Metals, and
            Towns, edited by T. Shaw, et al.  Routledge Press, London, pp. 53-60.

    1989   Wild Grass Seed Harvesting in the Sahara and Sub-Sahara of Africa. In Foraging
            and Farming: The Evolution of Plant Exploitation, edited by D. R. Harris and G. C.
            Hillman. Unwin-Hyman, London, pp. 17-98.

Harris, D. R., and G. C. Hillman, eds

    1989   Foraging and Farming: The Evolution of Plant Exploitation. Unwin-Hyman, London.

Hitchcock, A. S., and A. Chase

    1971   Manual of Grasses of the United States. United States Department of Agriculture,
            Miscellaneous Publications 200.

Kunkel, G.

    1984   Plants for Human Consumption. Koeltz Scientific Books, Koenigstein.
National Research Council

    1996   Lost Crops of Africa. Volume I: Grains. National Academy Press, Washington D.C.

Radford, A. E., H. E. Ahles, and C. R. Bell

    1964   Manual of the Vascular Flora of the Carolinas. University of North Carolina Press,
            Chapel Hill.

Steyermark, J. A.

    1963   Flora of Missouri. Iowa State University Press, Ames.

Van den Borre, A., and L. Watson

    1994   The Infrageneric classifications of Eragrostis (Poaceae). Taxon 43(3):383-422.

Yatskievich, G., and J. Turner

    1990   Catalogue of the Flora of Missouri. Braun-Brumfield, Inc., Ann Arbor.

Zawacki, A. A., and Glenn Hausfater

    1969   Early Vegetation of the Lower Illinois Valley. Illinois Valley Archaeological Program
            Research Papers vol. 1. Illinois State Museum Reports of Investigations No. 17.

Written by: Elisabeth Hildebrand

*Data for this table are taken from Hitchcock and Chase (1971), Steyermark (1963), Yatskievych and Turner (1990), Radfor et al. (1964) and personal observation (1996).