White clover
General poisoning notes:
White clover (Trifolium repens) is widely cultivated across Canada and has also become naturalized throughout much of the country. Under certain circumstances this valuable plant can cause problems in animals. White clover can cause bloat in livestock. It has caused laminitis in horses and cattle. After they are ingested, some varieties can liberate HCN, causing cyanogenic poisoning in animals. White clover is also reported to become estrogenic if infected with various fungi (Cooper and Johnson 1984, Cheeke and Schull 1985).
Description:
Perennial herbs, stoloniferous, glabrous to glabrescent. Stems 10-30 cm, prostrate, rooting at nodes. Leaves long petiolate, palmately 3-foliolate; stipules ovate-lanceolate, membranous, with veins green or red, sheathing at base, apex subulate; petiolule 1-1.5 mm; leaflets obovate to ovate, 6-20(-40) × 8-16(-25) mm, lateral veins 13 pairs, prominent on both surfaces, base cuneate, apex emarginate to broadly rounded. Flowers 20-50(-80), in terminal, globose umbels, 1.5-4 cm; peduncle equal to or longer than petiole; involucre absent; bracts lanceolate-ovate, membranous; pedicels 2-5 mm, reflexed after anthesis. Calyx 3-5 mm, veins 6-10; teeth shorter than tube. Corolla white, rarely pink-tinged, 5-12 mm, fragrant; standard elliptic, ca. 2 × wings and keel. Ovary sessile; ovules 3 or 4. Legume linear-oblong. Seeds 2-4, ovoid to reniform. Fl. and fr. May-Oct.
Trifolium repens L.
Nomenclature:
Scientific Name: Trifolium repens L.
Vernacular name(s): white clover
Other name: 白车轴草 bai che zhou cao
Scientific family name: Leguminosae
Vernacular family name: pea
Geographic Information:
Alberta, British Columbia, Labrador, Manitoba, New Brunswick, Northwest Territories, Nova Scotia, Ontario, Prince Edward Island, Quebec, Saskatchewan, Yukon Territory.
Toxic parts:
Al parts.
Notes on Toxic plant chemicals:
Two cyanogenic glycosides, linamarin and lotaustralin, are found in white clover. In young leaves, the cyanogen levels may reach 350 mg of HCN per 100 g of tissue, with lotaustralin predominating. Cyanogenesis is controlled by two independently inherited genes in white clover. Only plants possessing at least one dominant functional allele of both genes liberate HCN when damaged. Some cultivars are capable of liberating HCN and others are not (Poultan 1989).
Toxic plant chemicals:
Linamarin, lotaustralin.
Linamarin
Lotaustralin
Chemical diagram(s) are courtesy of Ruth McDiarmid, Biochemistry Technician, Kamloops Range Station, Agriculture and Agri-Food Canada, Kamploops, British Columbia, Canada.
Animals/Human Poisoning:
Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.
Cattle
General symptoms of poisoning:
Bloat.
Horses
General symptoms of poisoning:
Laminitis.
Notes on poisoning:
Laminitis is characterized by tenderness, swelling, and inflammation around the hooves. In Britain severe laminitis has been reported in cattle as well (Cooper and Johnson 1984).
