|Choice of species and errors in identification in student weed collections
David Wees1, S. Lussier1, T. Eades2, M. Abu-Dieyeh3 and E. Sivesind2.
1Farm Management and Technology Program, Macdonald Campus of McGill University,
21,111 Lakeshore Road, Ste-Anne de Bellevue, QC, CANADA, H9X 3V9
2Dept. of Plant Science, Macdonald Campus of McGill University, 21,111 Lakeshore Road,
Ste-Anne de Bellevue, QC, CANADA, H9X 3V9
3Dept. of Biology and Biotechnology, The Hashemite University, Zarqa, JORDAN
As part of an introductory course in botany, first-year students in an agricultural technology program were required to prepare a weed collection. They had to collect, mount and identify 15 different weed species of their choice. An analysis of 7 classes of 25 to 35 students each (years 2001 to 2007) found that the most commonly collected species (collected by at least 40% of the students) included lamb’s quarters (Chenopodium album), broad-leaved plantain (Plantago major), redroot pigweed (Amaranthus retroflexus), yellow foxtail (Setaria glauca) and dandelion (Taraxacum officinale). This as probably because these were abundant species in the area where most students collected specimens (farm lands, waste areas and lawns in southern Quebec and eastern Ontario, Canada), these species were often in flower or in seed at the time of collecting (late summer and early fall) and they were described in the field guide recommended for the course. The species most often misidentified (more than 20% of the specimens submitted) included annual sow-thistle (Sonchus oleraceus), perennial sow-thistle (Sonchus arvensis), yellow foxtail (Setaria glauca), green foxtail (Setaria viridis) and barnyard grass (Echinochloa crusgalli). The following species were correctly identified at least 95% of the time: broad-leaved plantain (Plantago major), velvetleaf (Abutilon theophrasti), hairy galinsoga (Galinsoga quadriradiata), pineapple weed (Matricaria matricarioides) and shepherds purse (Capsella bursa-pastoris).