Weeds

Bidens tripartite L. - Spanish Needles

Systematic position.

Family Asteraceae, genus Bidens L.

Synonyms.

Beggar`s Ticks, Trifid Bur-Marigold

Biological group.

Annual late spring weed; it can develop as winter weed.

Morphology and biology.

Plant 15-100 cm in height. Stalk erect, usually branched, with opposite branches, glabrous or sparsely pubescent. Leaves dark green, opposite, dentate, tripartite, with larger apical lobe, narrowing base in short winged leafstalk. Sometimes leaves are undivided (on small weakened individuals especially). Heads single or multiple at the end of branches, erect, as wide as they are long or nearly equal in length (6-15 mm). Perianth has double row. External leaflets of perianth (5 to 8) are green, oblong or elongate-linear, covered with short spicules at the edges, as long as or 2-3 times longer than the diameter of the head. Internal leaflets of envelope are shorter, brown-yellow, oval. Bracts wide-linear, as long as flowers. All flowers are tubular, yellow-brown. Hemicarps bladelike, compressed, 5-8 mm in length, 2-3 mm in width, with marginal setae and two or, less often, 3-4 apical spines. Blossoms in July-September. The maximal fertility is 12 thousand seeds. Seeds undergo a dormant period, germinating after 3 months. Spinules of hemicarps readily attach to human clothes, seed sacks, and animal wool, thus spreading within environment. Seeds sprout non-simultaneously.

Distribution.

All of Europe (except for Arctic regions), the Caucasus, all of Siberia, the Far East, Central Asia, Northern Africa, Minor Asia to India, Mongolia, Japan, Korea, China, the Himalayas, Tibet, Iraq, Iran, North America, and Australia.

Ecology.

Thickets of the weed occur on moist alluvial soils along river shores. Prefers fertile, friable, and sandy ground inclined to flooding. Seeds sprout from a depth of less than 3-4 cm. The minimal temperature for germination is +8-10°C; optimum is +24-30°C.

Economic significance.

Contaminates vegetable cultures and gardens, occurs in fields of summer and winter cereals. Control measures include removing stubble, autumn plowing, seed cleaning, pre-sowing treatment of ground, inter-row treatments, herbicide treatments (if necessary), and consistent crop rotation.

Reference citations:

Anon. 1996. Weeds on sugar beet. Berlin: Hoehst Shering AgrEvo Gmbh. 148 pp. (In Russian)
Chesalin G.A. 1975. Weeds and their control. Moscow: Kolos. 256 pp. (In Russian)
Komarov, V.L., ed. 1959. Flora of the USSR. Moscow & Leningrad: AN SSSR. V. 25: 557-558. (In Russian)
Veselovs'kii I.V., Lisenko A.K., Man'ko Yu.P. 1988. Atlas-synopsis of weeds. Kyiv: Urozhai. 60 pp. (In Ukrainian)

© I.N. Nadtochii