Carolus Linnaeus described common groundsel, Senecio vulgaris, in his Species Plantarum, published in 1753 (2). The generic name is derived from the Latin senex meaning old or old man, the pappus resembling a white beard (4). Vulgaris is from the Latin vulgari meaning common, usual, or ordinary (7, 18). Forms of the word groundsel started appearing in English by A.D. 700 and the word metamorphosed from groundie-swallow, grundy-swallow, grunswel, groun swell, groundsell and finally, in 1562, to groundsel when Turner used the word in his Herbal. "Senecio is named in English the groundsel," he wrote (16).
The genus Senecio L., in the Compositae, is cosmopolitan, with 1500 species, exclusive of Antarctica. It is one of the largest genera of seed plants and even today its limits are not fully understood (11). Senecios are found in almost every country throughout the world (9). The genus includes plants of widely diverse habit-trees, shrubs, climbers, pachycauls, prostrate growers, and herbs. Some species are cultivated ornamentals, e.g., S. bicolor (dusty miller), and some are weeds (11). Nearly 50 species of hardy and half-hardy annual, biennial, and perennial senecios occur in North America and about 60 in Europe (8). Worldwide, about 25 species contain alkaloids toxic to humans and livestock. Seven species are suspected or proved to be toxic in the U.S.
DESCRIPTION, DISTRIBUTION, AND COMMON NAMES
Common groundsel is an erect, variable, sometimes downy annual or biennial, up to 45 cm tall (9). Its stems are succulent, hollow, slightly angled, much branched, and leafy on top (5). It has slightly fleshy, narrow pinnately lobed leaves, and bears small, yellow usually rayless flowers (9). Plants produce flowers and achenes for much of the year (9, 10). The achenes are oblong, finely ribbed and minutely hairy, with a very copious, fine, white pappus, by which they are widely wind-dispersed (5). In 1859, Darlington (4) called common groundsel "A homely little weed in waste ground from New England to Pennsylvania ... Whether it is likely to become trouble-some to our farmers is not yet ascertained." Obviously he greatly underestimated the tenacity of the weed.
Augustin Pyramus de Candolle (1778-1841) reported that common groundsel had migrated almost everywhere with European man (4). It is now found throughout Europe, its native home, and Russian Asia, in cultivated soils, gardens and waste places; it is naturalized in numerous other countries (9). Groundsel is especially prolific and plentiful on fertile soil, sometimes occurring in almost incredible quantities, completely smothering any young crop (10). In North America, common groundsel is found from Newfoundland and Hudson Bay to Virginia and North Carolina, west to Minnesota, South Dakota, and Michigan. And it also is found on the Pacific Coast (2, 5). In the U.S., other common names for groundsel include grinsel, simson, birdseed, and chickenweed (2, 5). In England, it is also known as grundy, swallow, simson, sention, and ground glutton (9). Groundsel is often grown in Europe to furnish green food for cage birds and poultry. At the turn of the century, land owners were advised to combat groundsel seedlings in the garden by the repeated and vigorous use of the hoe. In field cultivation, farmers were urged to keep both the horse and hand hoe busy in root crops (10). into toxic pyrroles. Many such transformed alkaloids are toxic to horses, cattle and swine; sheep are less susceptible to groundsel. Younger animals are more readily affected by the plants. A calf may be poisoned if the mother consumes the plants during pregnancy (12). Pyrrolizidine poisoning is cumulative. Signs of poisoning may first appear from a few weeks to 5 mo after plant consumption; during this period, animals may appear in excellent condition and even gain weight (12).
It is rare for a single large dose of alkaloid to cause acute poisoning with immediate signs. More common are chronic cases resulting from small daily doses of groundsel over a period of weeks or months. Cattle and horses may consume 10% or more of their body weight of groundsel before poisoning occurs; symptoms appear within a few weeks up to a few months. These variations depend on the growth stage of the groundsel being consumed, as well as any stresses acting on the animals at the time (12). Although groundsel is not preferred forage, livestock may inadvertently eat it along with other forage in spring on range or pasture. Groundsel leaves are the most toxic part of the plant. Pyrrolizidine alkaloids are not destroyed during plant drying or fermentation in silage. Consequently, hay is a common source of pyrrodizidine poisoning, especially the first cutting. Unfortunately, no current popular treatment for pyrrolizidine poisoning offers much hope to the affected animals (12).
Do precocious (early reproducing) variants of common groundsel have a selective advantage in well-weeded sites, e.g., botanic gardens vs. field margins? British researchers provided evidence of trade-offs in life-history evolutions, finding that precocious variants were comparatively dwarf at first fruiting and shorter-lived (17). Frequent and thorough weeding of a site may act as a selection pressure favoring those variants of common annual weeds which are capable of early reproduction. Annual weeds from botanic and other gardens had a faster rate of development than plants from less well weeded or non-weeded habitats. Samples of groundsel from botanic gardens were, on average, shorter at maturity than other plants. Since precocious variants are likely to have developed from slower-developing plants, reduced height may be a trade-off for early reproduction. A trade-off exists
Formerly, common groundsel had several medicinal uses. The great herbalist Pliny the Elder (A.D. 23-79) believed that groundsel was a useful remedy for toothache and advised the sufferer to uproot the plant with his hands, touch the tooth concerned three times, spit on the ground each time, then reset the plant in the ground; should it root and grow again, the pain would go away (9)! As a healing herb, groundsel was known to the Anglo-Saxons as gundeswele meaning, perhaps, ground eater or swallower, referring to the invasive habit. By the 15th century, it was highly regarded as a medicinal plant and was cultivated as such in monastic gardens. Gerard (6) tells us: "The leaves stamped and strained into milke and drunke, helpe the red gums and frets in children . . .Dioscorides saith, `That with the fine pouder of frankincense it healeth wounds in the sinues. "'
Culpeper (3) proclaimed the plant's many virtues, writing: ". . . is cooling in inflammations and is an easy emetic when made like tea. Taken in ale, it acts against the pains of the stomach, strangury (a slow and painful discharge of urine) and jaundice ... it destroys worms, and is useful in scrofulous tumors and inflammations of the breast and scald head." He recommended it, outwardly or inwardly "as a good purgative; for the gripes and colics of infants; the sore breasts of women; to provoke urine; for gravel in the reins and kidneys; and knots and kernals in any part of the body..." He added, "An infusion of it taken inwardly cures staggers and bot-worms in horses." Now, the whole of the fresh or dried herb is prescribed for destroying intestinal parasitic worms, for increasing perspiration, and for its diuretic principles, and in the form of a tea is taken for disordered liver function, or in slightly stronger infusions when a laxative is required. It is also administered for suppressed or delayed menstruation, and for painful or irregular menstruation in young girls. Additionally, it is sometimes included in lotions for the eyes, and in applications for smoothing rough or chapped hands (9).
Consumption of large quantities of groundsel by certain classes of livestock causes tissue death (necrosis) and scarring of their livers, which become small, hard, and less functional (cirrhotic) (12). Common groundsel contains . pyrrolizidine alkaloids. While these alkaloids are not toxic, the liver converts them where a benefit realized through a change in one trait is linked to a cost paid out through a change in another (17).
In England, researchers focused on the germination behavior of seed of two populations of non-radiate S. vulgaris var. vulgaris L.-the most common variant of the species (14). Would they be different? Fresh seed derived from a Mediterranean population showed strong innate dormancy over a wide temperature range. In contrast, fresh seed of British groundsel exhibited > 80% germination at 20 C (14). The innate dormancy exhibited by seed on non-radiate Mediterranean groundsel enables the species to adopt a winter annual life cycle which is typical of Mediterranean ephemerals (14).
In 1970 s-triazine resistance was found in common groundsel. Since then, the occurrence of weed species resistant to s-triazine herbicides has become widespread (15). Many of the triazine-resistant weed species initially appeared in the cooler regions of the temperature zones. Could this pattern of initial discovery be due to a differential temperature effect on the productivity of triazine-resistant and -susceptible biotypes (13)? This assumption led researchers to investigate the effect of growth temperature on biomass production and photo-synthesis of nearly-isonuclear triazine-resistant and -susceptible common groundsel (13). They found that plants containing the susceptible chloroplast genome produced more biomass and had greater photosynthetic rates than those with the resistant chloroplast genome, when in association with the same nuclear genome. There was no differential temperature effect on biomass production of isonuclear plants possessing resistant or susceptible chloroplast genomes (13).
EFFECTS OF ELEVATED C02 AND DROUGHT
The current unprecedented rise in atmospheric C02 will have significant direct effects on terrestrial vegetation. And it is likely to increase the mean global temperature and alter patterns of precipitation (1). How would such conditions impact a weed like common groundsel? Researchers decided to find out. They learned that C02 and water had a significant effect on the way groundsel root systems filled a soil matrix. Elevated C02 resulted in more branched, longer root systems that foraged through larger volumes of soil. Under elevated C02 and a low water supply, root systems had branching and foraging patterns and root length similar to those grown under ambient C02 with a high water supply (1). The bottom line: water had a more pronounced effect on the growth rate of groundsel than did CO2. Under elevated C02 the intensity of foraging groundsel root systems might be unchanged while the extent of foraging by these root systems, as indicated by the horizontal spread of roots, may be increased (1).
1. Bemtson, G. M. and F 1. Woodward. 1992. The root system architecture and development of Senecio vulgaris in elevated COZ and drought. Funct. Ecol. 6:324-333.
2. Britton, N. L. and A. Brown. 1898. An Illustrated Flora of the Northern United States, Canada and the British Possessions. Volume 3. Charles Scribner's Sons, New York.
3. Culpeper, N. 1802. Culpeper's Herbal or The Complete English Family Physician, with additions by G. A. Gordon. Hogg and Co., London. 416 p.
4. Darlington, W 1859. American Weeds and Useful Plants. Orange Judd & Company, New York. 460 p.
5. Georgia, A. 1942. Manual of Weeds. The Macmillan Co., New York. 593 p.
6. Gerard, J. 1928. Gerard's Herbal. Houghton Mifflin Co., Boston. 69 p.
7. Jaeger, E. C.1944. A Source-book of Biological Names and Terms (2nd Ed.). Charles C. Thomas, Springfield, IL. 257 p.
8. Kingsbury, J. M. 1964. Poisonous Plants of the United States and Canada. Prentice-Hall, Inc., Englewood Cliffs, NJ. 626 p.
9. LeStrange, R. 1977. A History of Herbal Plants. Angus and Robertson, Publishers, London. 304 p.
10. Long, H. C. 1910. Common Weeds of the Farm and Garden. Frederick A. Stokes Co., New York. 451 p.
11. Mabberley, D. J. 1989. The Plant-Book. Cambridge University Press, Cambridge. 706 p.
12. McHenry, W. B., R. B. Bushnell, M. N. Oliver, and R. F. Norris. 1990. Three Poisonous Plants Common in Pasture and Hay. Univ. Calif. Coop. Ext. Pub. 21483, 9 p.
13. McCloskey, W. B. and J. S. Holt. 1991. Effect of growth temperature on biomass production of nearly isonuclear triazine-resistant and -susceptible common groundsel (Senecio vulgaris L.). Plant, Cell and Environment 14:699-705.
14. Ren, Z. and R. J. Abbott. 1991. Seed dormancy in Mediterranean Senecio vulgaris L. New Phytol. 117:673-678.
15. Ryan, G. F. 1970. Resistance of common groundsel to simazine and atrazine. Weed Sci. 18:614-616.
16. Simpson, J. A. and E. S. C. Weiner. 1989. The Oxford English Dictionary, 2nd Ed. Clarendon Press, Oxford.
17. Theaker, A. J. and D. Briggs. 1993. Genecological studies of groundsel(Senecio vulgaris L.). IV. Rate of development in plants from different habitat types. New Phytol. 123:185-194.
18. Zimdahl, R. L. 1989. Words and Weeds. Iowa State University Press, Ames. 125 p.