1	Plants usually branched; basal leaves usually withered at anthesis; upper leaves similar to lower leaves		(2)
+	Plants usually unbranched; basal leaves usually persistent; upper leaves gradually smaller than lower leaves		(3)
2 (1)	Blade of basal and proximal cauline leaves 2-6 mm wide; bracts among capitula linear, oblanceolate, or oblong-oblanceolate, surpassing glomerules or not.		1 G. calviceps
+	Blade of basal and proximal cauline leaves 4-18 mm wide; bracts among capitula spatulate to oblanceolate, at least proximal ones surpassing glomerules.		2 G. pensylvanica
3 (1)	Bracteal leaves short, spatulate to oblong; leaves spatulate-oblong, apex obtuse		(4)
+	Bracteal leaves distinct, linear; leaves linear, filiform, or linear-lanceolate, apex acute to acuminate		(5)
4 (3)	Leaves adaxially glabrous or glabrate; involucre 2.5-3 mm, base glabrous; outer phyllaries elliptic-obovate to broadly ovate-elliptic, apices rounded to obtuse; bisexual florets 2 or 3.		3 G. impatiens
+	Leaves adaxially sparsely arachnoid (hairs persistent, evident); involucre 3-4.5(-5) mm, base (imbedded in tomentum) often sparsely arachnoid on proximal 1/5-1/2; outer phyllaries ovate, ovate-triangular, or ovate-lanceolate, apices acute to acuminate; bisexual florets 3 or 4.		4 G. purpurea
5 (3)	Leaves usually 3-veined.		5 G. norvegica
+	Leaves 1-veined		(6)
6 (5)	Leaves linear or linear-lanceolate, 5-8 mm wide; spikes long and loose; involucre 3-5 mm in diam.		6 G. sylvatica
+	Leaves linear or filiform, 1-3 mm wide; spikes short and dense; involucre 2-3 mm in diam		7 G. nanchuanensis