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Description:
Cooley's meadow-rue is a perennial herb originating from an underground rhizome (USFWS 1990). In shaded conditions, it grows with lax stems often leaning against other plants (Patrick et. al. 1995) or may trail along the ground, but under ideal conditions, in full sun, these stems are erect (USFWS 1990). Cooley's meadow-rue grows up to 0.8 to 1.5 m in height (Patrick et. al. 1995) but may grow as high as 2 m on recently burned sites (USFWS 1990). Cooley's meadow-rue has narrower leaflets with fewer lobes than any other Thalictrum. Its stem and basal leaves are highly variable both in shape and size. The are complexly divided with leaflets ultimately in either three's and five's. The undersurface of the leaves exhibit a whitish bloom and the leaf margins tend to curl slightly under. The terminal leaflets are broader in the lower stem and basal leaves, usually narrowly ovate, mostly 2 to 3 times longer than wide and approximately 15 mm in length by 7 mm in width. The upper stem leaves have narrower terminal leaflets, usually narrowly lanceolate and mostly 5 to 10 times longer than wide. The leaflets are approximately 20 mm in length by approximately 4 mm in width and mostly entire. Only a few of the terminal leaflets have 2 to 3 short lobes or have coarse teeth. Cooley's meadow-rue is dioecious meaning female and male plant flowers are produced on different plants (Patrick et. al. 1995). The male to female ratio is 3 to 1 (USFWS 1990). The flowers are produced terminally in an open, branched panical from late-May to June (Patrick et. al. 1995). If the plants grow in partial shade instead of full sun, their flowering may be delayed by as much as 2 weeks (USFWS 1990). The flowers lack flower petals and have 4 to 5 yellowish to greenish sepals approximately 1.5 to 2.0 mm in length. The species produces short anthers approximately 1 to 2 mm in length on faint white to lavender, club shaped filaments. The fruit of Cooley's meadow-rue, produced in clusters, appears from July to September, but persisting through October. The fruit which is called an achene has a short stalk about 5 to 6 mm in length with numerous longitudinal ribs running across its outer surface (Patrick et. al. 1995).
Habitat:
Cooley's meadow-rue inhabits sunny, moist places such as open, savanna-like forest edges and clearings, wet savannas over calcareous clays, and ecotones between wet savannas and non-riverine swamp forests. Soils are basic, sandy loams. The species is found along utility and highway rights-of-way in former savanna habitats.
Range:
Cooley's meadow-rue is an endemic of the southeastern Coastal Plain from Florida to North Carolina. According to the USFWS (1990) eleven populations of this plant remain in Pender, Onslow, Brunswick, and Columbus Counties in North Carolina, and one population exists in Walton County, Florida. All of the plant sites are on privately-owned land. The precise number of plants in each population is unknown; two North Carolina populations recently lost plants as a result of timber cutting and road grading. Probably, the total number of remaining plants is less than 8OO plants. A population, reported from Worth County, Georgia, was apparently mistakenly identified as Cooley's meadowrue. Another population formerly in New Hanover County, North Carolina, has been extirpated. The remaining North Carolina populations are probably fragments of three larger populations. The six sites in Onslow and Pender Counties are all within a 6.5-kilometer radius, the 3 sites in Columbus County are within a 4-kilometer radius, and the 2 sites in Brunswick County are within a 1.5-kilometer radius (USFWS 1990). At least six historical occurrences have been lost to conversion of habitat to silviculture or agriculture and these factors continue to threaten some of the few remaining populations. Throughout the range, fire suppression has increased the relative rarity of suitable habitat (which was probably never abundant) and contributed to the species' overall decline. The remaining populations will need active management with prescribed burns in order to survive (NatureServe 2003).
References
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