Intriguing World of Weeds Velvetleaf1 LARRY W. MITICH2 INTRODUCTION it is still spreading: for example, it was first reported in the Netherlands in 1981 (7), and it has become a Velvetleaf (Abutilon theophrasti Medicus. #3 ABUTH), a large, vigorously competitive plant, problem in California only within the last decade. Its produces thousands of long-lived seeds. Its hard-coated northern and southern ranges are expanding in the U.S. seeds germinate throughout the (1), and it is moving into eastern Canada (12). warm season, making control diffi­ The spread of velvetleaf is in part due to use of com cult. Seeds, adult plants, and decay- herbicide combinations with low rates of atrazine, less ing plant parts contain or produce use of 2,4-D in com, and less cultivation. Moreover, allelopathic chemicals which ag­ triazine-tolerant velvetleaf is becoming a problem; in gravate the effects of velvetleaf on 1986, for example, triazine-tolerant velvetleaf was re­ surrounding crop plants. Velvetleaf ported from a Maryland field where com had been must be attacked with multiple continuously cropped for five yr (5). strategies; reliance on single herbi­ cides in the past has allowed velvet­ NAME HISTORY leaf to spread and even develop her­ Around 900 B.C., the Arabic philosopher bicide tolerance. A vicenna--or Tun-Sina-coined the word "abutilon" for plants resembling a mallow or mulberry. Theophrastus (372-287 B.C.) used the Greek word "side," meaning DISTRIBUTION AND HABITAT water plant, for the plants we now know as sidas and Velvetleaf originated in either China or India. Its use velvetleaf. Theophrastus, regarded as the father of mod­ as a fiber crop in China dates to 2000 B.C. or earlier; it em botany, was a Greek philosopher, botanist, writer, is still grown there for fiber which is used to make and associate of Aristotle; but we don't know why he ropes, coarse cloth, nets, paper, and caulk for boats (8). attached a watery name to these terrestrial, nonsuccu­ Whether as a 'stowaway' in crop seed or as an lent species (13). intended fiber crop, velvetleaf arrived in North America Carolus Linnaeus (1707-1778) classified velvetleaf probably before 1700, and was widespread on the East as Sida abutilon, honoring both philosophers. Its genus Coast by the early 1700s. Because the colonies desper­ companions included such plants as prickly sida (Sida ately needed fiber for rope and cloth, velvetleaf was spinosa L. # SIDSP). widely cultivated in the mid 1700s. Although attempts The genus Abutilon is attributed to Philip Miller to process velvetleaf fiber never succeeded economical­ (1691-1771) (2), chief gardener at the Chelsea Physic ly, U.S. farmers continued to cultivate it for more than Garden from 1721 until his death. Miller was reluctant 100 years (8). to use Linnaeus' binomial system, even after the master Velvetleaf now inhabits waste places, cultivated taxonomist visited the Garden in 1736; not until 1768 fields-especially com and soybeans-and fence rows. It did Miller apply Latin to his specimens, in the seventh is widespread between 32° and 45°N in North America, edition of his internationally valued Gardener's Dic­ though other members of its genus are all tropical or tionary. subtropical (12). It is common in Europe, particularly in The "Medicus" citation which appears after our cur­ southeastern and Mediterranean countries. Worldwide, rent Abutilon theophrasti comes from Friedrich Casimir Medicus [Medikus] (1736-1808) (2), director of the garden at Mannheim during the late 18th century. Medicus criticized Linnaeus for occasionally defining 1No. 33 of the series "Intriguing World of Weeds." Contributions are welcome and will be acknowledged. Send contributions to Larry W. Milich. genera based on single members, then adding new 2Ext. Weed Sci., Dep. Bot., Univ. Calif., Davis, CA 95616. species while ignoring his own generic characteristics. 3Letters following this symbol are a WSSA-approved computer code from Composite List of Weeds, Revised 1989. Available from WSSA 309 In 1787 Medicus published a volume in which he W. Oark St., Champaign, IL 61820. ' rearranged the Malvaceae, placing Sida abutilon in the 253 Weed Technology. 1991. Volume 5:253-255 MITICH: VELVETLEAF genus Abutilon with the specific epithet theophrasti. Table 1. Percent of velvetleaf seed remaining after 4 yr under various cultural regimes, starting with 53 million seeds per acre (4). Theophrasti, of course, refers to Theophrastus. In one of his three works published between 1788 % Seed Culture remaining and 1791, Joseph Gaertner (1732-1791) reclassified the Continuous alfalfa S6 plant as Abutilon avicennae, naming the plant for the Chemical fallow, no cultivation 37 Arab philosopher instead of the Greek. Perhaps Gaert­ Continuous fallow, two plowings, monthly tillage 10 ner felt that Avicenna's earlier claim earned him prece­ dence. However, scientific precedence held sway, and Medicus' name was restored. remain viable for 50 yr when stored in the soil (12); Velvetleaf has been known as abutilon, butterprint, one researcher reported 43% germination after 39 yr of elephant ears, and piemarker. A member of the mallow burial (11). The seeds and seed coats also have chemi­ family, it has been called Indian mallow or, like many cals and microbial agents which inhibit growth of bac­ of the Malva genus, buttonweed - after the shape of its teria and fungi. seed pods. Its use as fiber has earned it the names The data in Table 1 demonstrate the difficulty of cottonweed, China jute, abutilon hemp, Manchurian depleting a velvetleaf seedbank even under intensive jute, and American jute (12). farming. Velvetleaf germinates throughout the summer. Even RELATED PLANTS small end-of-season plants can successfully flower and seed. Velvetleaf is efficient under conditions of low Velvetleaf is a member of the Mal­ sunlight; it grows well when partially shaded and can vaceae, a family which includes cot­ produce seed under a crop canopy. Its root growth ton, our most important fiber crop; exceeds that of redroot pigweed, green foxtail, and velvetleaf fibers, however, come from many other weeds (6). Because of these abilities, and the stem and branches of the plant because it can grow tall enough to overtop com, velvet­ rather than the flowering parts. In­ leaf can infest a com field even after the crop forms a terestingly, I found nothing in the dense canopy. literature about velvetleaf seeds being Significant competition effects have been measured used as food, though other members in corn, soybeans, sugarbeets, and cotton (various, sum­ of the Malvaceae have edible seeds or marized in 12). Velvetleaf also makes itself at home in seed pods - including okra, members dry beans, alfalfa, tobacco, and peanuts. of the genus Malva, and cotton, whose In 1982, North American com growers spent $114 seeds provide an edible oil. In million on velvetleaf control. Soybean growers spent researching this article I personally . found velvetleaf $229 million on control; left uncontrolled, velvetleaf seeds rather tasty when dried, something like sunflower seeds. Moreover, in a miniscule way I helped to deplete would have cost an estimated $1 billion in soybean the world's velvetleaf seedbank. losses alone (8). In soybean fields, 2.5 to 5 velvetleaf 2 The genus Abutilon includes about 150 species, sev­ plants/m typically cause yield losses from 25% to 40% eral of them grown ornamentally. Varieties of A. hybri­ (various, summarized in 12). In 1987, velvetleaf was dum Hort., in particular, are known as Chinese lantern; ranked the most troublesome weed in soybeans in 9 of other ornamental abutilons are called flowering maple the 14 north central states (6). or parlor maple (2). Velvetleaf also has allelopathic effects on crop plants. Extracts from velvetleaf leaves and seeds have been shown to depress germination and growth of alfal­ BIOLOGY AND ECONOMIC IMPACT fa, com, radish, soybean, and turnip seedlings (various, Velvetleaf is self-fertilizing and can produce up to summarized in 12). In the field, velvetleaf plant 17 000 seeds per plant (12). Velvetleaf seeds have residues reduce yields of c~m and soybeans (3). The tough seed coats which protect them against digestion mechanism of allelopathy is under investigation; though by farm animals; in fact, experimental germination of velvetleaf trichomes exude inhibitory substances, these velvetleaf seed requires scarification with 1 M sulfuric may decay too rapidly in the field to interfere with acid for 15 min or boiling for 1 min (9). Seeds can other species (10). 254 Volume 5, Issue 1 (January-March) 1991 WEED TECHNOLOGY Velvetleaf hosts a number of crop pests, including 2. Bailey, L. H., and E. Z. Bailey. 1976. Hortus Third. MacMillan Publishing Co., Inc., New York. pathogens [particularly the soybean pathogens Phomop­ 3. Bhowmik, P. C., and J. D. Doll. 1982. Com and soybean response to sis sojae, Colletotrichum dematium, and C. gloeospori­ allelopathic effects of weed and crop residues. Agron. J. 74:601-«>6. 4. Lueschen, W. E., and R. N. Andersen. 1980. Longevity of velvetleaf oides], insects [including tobacco budworm (Heliothis (Abuttlon theophrasti) seeds in soil under agricultural practices. Weed virescens), bollworm (H. zea), and flea beetle (Systena Sci. 28:341-346. 5. Ritter, R. L. 1986. Triazine resistant velvetleaf and giant foxtail conttol frontalis) - a pest of com], and nematodes (including in no-tillage com. Proc. Northeast Weed Sci. Soc. 40:50. several species of Meloidogyne). 6. Roeth, F. W. 1987. Velvetleaf - coming on strong. Crops Soils Mag. 39:10-11. In general, velvetleaf is more of a problem in 7. Rotteveel, A.J.W. 1981. Alien weeds, a menace to the Netherlands. monocultures - where one crop is grown year after year Ann. Rep. Neth. Plantenziek:tenkundige Dienst p. 145-149. 8. Spencer, N. R. 1984. Velvetleaf, Abutilon theophrasti (Malvaceae), - than in rotational sequences, because it has a better history and economic impact in the United States.