Helianthus annuus L. var. macrocarpus

Sunflower

Asterceae (Compositae)

       Helianthus annuus fruits (achenes) and seeds (kernels) are commonly found in the archaeological record of the eastern United States. When sunflower is present, the achene (Figure 1) is likely to be fragmented or split in half. Whole achenes are not common in flotation samples, although caches of them have been recovered. Kernel fragments, as well, are likely to be broken and fragmented. Large sunflower fragments can be readily identified, while smaller fragments may not be distinguishable from Iva annua.

 

Description

       The sunflower fruit (achene) is a single seed enclosed in a shell (pericarp). The shell is thin and has longitudinally oriented ridges on its surface. According to Yarnell (1978:291), "the original wild ancestral sunflowers probably had mean achene lengths of 4.5 to 5.0 mm." Modern achenes range from 6 mm to 20 mm in length and 4 mm to 6 mm in width. Archaeobotanical samples have approximately the same size range as the modern varieties (Crites 1993). The kernel is long and round with a point at the proximal end (Figure 2). Since the plant is a diocotolydon, the seed often splits into halves.

       In order to estimate the sizes of sunflower achenes and kernels before they were charred, archaeobotanists apply a correction factor to adjust for shrinkage due to carbonization (Yarnell 1978, from Heiser 1953):

 

            Uncarbonized kernel length = 1.31 x (carbonized achene length)

            Uncarbonized kernel width  = 1.59 x (carbonized achene width)

            Uncarbonized achene length = 1.11 x (carbonized achene length)

            Uncarbonized achene width  = 1.26 x (carbonized achene width)

 

       The fruits of domesticated sunflowers (Helianthus annuus var. macrocarpus L.) and sumpweed (Iva annua var. macrocarpa (S. R. Blake) R. Jackson) are similar in texture and in their high oil contents. Sunflower seeds are longer than they are wide, while sumpweed seeds tend to be shorter and relatively wider than sunflower (Yarnell 1978). Uncarbonized sunflower pericarps are sometimes striped black, gray, and white. The sunflower kernel lacks ridges and is not heart shaped like sumpweed. Smaller fragments of sunflower achene are indistinguishable from sumpweed and other thin shelled seeds.

       The earliest probable cultivated sunflowers from Tennessee have achene sizes averaging 7 mm to 7.5 mm in length and 3 mm to 3.5 mm in width, adjusted for carbonization (Crites 1993). Over time, the achene sizes of sunflower increased. Collections of sunflowers from Middle Woodland and Late Woodland sites are larger than those from Early Woodland sites, and smaller than Mississippian samples.

 

Archaeological Distribution

       Wild sunflower (Helianthus annuus var. lenticularis (Dougl.) Steyerm.) is thought to have originated in the central to western United States and then spread into human disturbed areas from there (Heiser 1985). Sunflower appears to have been domesticated in the midwestern United States. Most evidence for early use and evolution of sunflower comes from sites in Tennessee, Arkansas, and Kentucky. By early historic times, domesticated sunflower was distributed from Texas to North Carolina and as far North as Quebec (Yarnell 1978).

The Modern Plant and Its Distribution

       Modern varieties of Helianthus have a wide range across North America. More than fifty species of Helianthus sp. are represented in North America. Weedy forms of sunflower can be spotted in the Midwest and Great Plains areas. Truly wild forms are most commonly found in the southwestern United States. The common domesticated sunflower generally has one large seed head (Figure 3), and the seeds are not naturally dispersed by the plant. The plant is a member of many home gardens.

 

Discussion

       The sunflower has become a fad in American culture today. Peering through magazines and catalogues, one finds sunflowers on umbrellas, book bags, jewelry, clothing, coffee mugs, and just about everything one could possible buy. Sunflower is used extensively in oil and food production due to its high oil content. Asch and Asch (1985:164) state, "among the cultivated plants of New World origin, the only one from north of Mexico that has become an important crop in modern times is the common sunflower."

 

References

Asch, D. L., and N. B. Asch.

    1985   Prehistoric Plant Cultivation in West-Central Illinois. In Prehistoric Food Production in
            North America, edited by R. I. Ford, pp. 149-203. Anthropological Papers, No. 75.
            Museum of Anthropology, University of Michigan, Ann Arbor.

Crites, G. D.

    1993   Domesticated Sunflower in Fifth Millennium B.P. Temporal Context: New Evidence
            From Middle Tennessee. American Antiquity 58:146-148.

Heiser, C. B.

    1953   The Archaeological Record of the Cultivated Sunflower with Remarks Concerning the
            Origin of Indian Agriculture in Eastern North America. Unpublished manuscript.

    1985   Some Botanical Considerations of the Early Domesticated Plants North of Mexico. In
            Prehistoric Food Production in North America, edited by R. I. Ford, pp. 57-72.
            Anthropological Papers, No. 75. Museum of Anthropology, University of Michigan, Ann
            Arbor.

Steyermark, J. A.

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

Yarnell, R. A.

    1978   Domestication of Sunflower and Sumpweed in Eastern North America. In The Nature
            and Status of Ethnobotany, edited by R. I. Ford, pp. 289-299. Anthropological Papers,
            No. 67. Museum of Anthropology, University of Michigan, Ann Arbor.

Written by: Kenneth J. Keller