. The Canadian field-naturalist. 262 The Canadian Field-Naturalist Vol. 87 1504, OS). During a return trip on 17-18 June 1972, no trace of Triosteum angustijolium could be found. Valerianella umbilicata and V. intermedia, however, were more abundant than in 1971 with approximately 100 plants scatter- ed throughout the thicket. Two vouchers each of V. umbilicata (Duncan 2015A, DAO, OS) and V. intermedia (Duncan 2015, DAO, WMU) were collected. Triosteum angustijolium is the most southern species of its genus, which is widespread in the eastern United States (Lane 1954). T. angusti- jolium occurs
. The Canadian field-naturalist. 262 The Canadian Field-Naturalist Vol. 87 1504, OS). During a return trip on 17-18 June 1972, no trace of Triosteum angustijolium could be found. Valerianella umbilicata and V. intermedia, however, were more abundant than in 1971 with approximately 100 plants scatter- ed throughout the thicket. Two vouchers each of V. umbilicata (Duncan 2015A, DAO, OS) and V. intermedia (Duncan 2015, DAO, WMU) were collected. Triosteum angustijolium is the most southern species of its genus, which is widespread in the eastern United States (Lane 1954). T. angusti- jolium occurs from Connecticut to eastern Kansas and eastern Texas, and south to Ala- bama and North Carolina (Figure 2). Its dis-. FiGURE 2. Distribution of Triosteum angustijolium in North America (after Lane 1954). Line indicates the maximum extent of the Wisconsin glaciation. The star indicates location of col- lection from Pelee Island. Sohd circles indi- cate the location of one or more collections. Goode Base Map, copyright by the University of Chicago, permission by Department of Geography. tribution is almost exclusively south of the boundary of the maximum extent of the Wis- consin glaciation. The magnitude of the range extension for this species is not known. The distribution in Figure 2 would indicate a 150-mile disjunction north of the nearest known location in southern Ohio. Hauser (1965) mapped T. angustijolium from several locations north of the Wisconsin glacial boundary in Ohio. The Pelee Island location, according to this treatment, would then be approximately 50 miles north of the nearest known location. Problems exist, however, in Hauser's treatment of Triosteum in Ohio. The specimens he examined from several of these northern localities have character states not found in T. angustijolium. Hauser specifically mentioned that many of the specimens from these northern locations have more than one flower per leaf axil and that the stipules do not extend beyond the sepals. A
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