Tower Mustard

Tower mustard typically reaches 40 to 120 centimeters in height at full growth, but may be stunted to just 30 centimeters or might reach 1.5 meters in height in exceptional circumstances. It is typically a biennial herb, but may occasionally be a short lived perennial. Plants have a tap-root and fibrous side-roots. Plants usually have several erect, usually unbranched stems which are grey in the lower parts with a covering of simple hairs, but green and glabrous (hairless) above. The leaves occur in a basal rosette initially, and later grow alternately on the main stem and branches. The basal leaves are blunt and toothed or pinnatifid and up to 15 cm long, whereas the stem and branch leaves become progressively smaller, less divided and more pointed, clasping the stem. The basal leaves are usually covered in hairs (pubescent) on the upper surface, but in rare cases they may be hairless. They vary in shape from spoon shape with a narrow base and wide at the end (spatulate), to being a narrow spear point with the widest point in the middle (oblanceolate), or a rounded rectangle longer than wide (oblong) with a broad point. They are typically 5 to 12 centimeters long, but may be only 4 cm or as much as 15 cm in length. …

The native distribution of tower mustard is moderately uncertain with sources having some details of its range different. POWO lists it as native to all parts of Europe with the exceptions of Ireland, Sardinia, and Corsica. They list it as growing in much of the northwest of Temperate Asia from Turkey and Iran northwards into central Asia and from Chita Oblast, Irkutsk Oblast, and Krasnoyarsk Krai westwards in Siberia. In the more southerly parts of Asia POWO lists it as native to Korea, Japan, Mongolia, Manchuria, north-central China, southeast China, Xinjiang, Nepal, and the western Himalayas. In addition they list it as introduced to Primorsky Krai, Sakhalin Island, and the Kuril Islands. In Africa POWO lists it as native to Algeria, Kenya, Morocco, Rwanda, Tanzania, Uganda, and the Democratic Republic of the Congo, with it being introduced to Lesotho and two parts of South Africa, KwaZulu-Natal, the Cape Provinces, and the Northern Provinces. In North America POWO lists it as native to all parts of Canada with the exceptions of Newfoundland and Labrador, Nova Scotia, Prince Edward Island, and Nunavut. …