a low-growing evergreen North American plant with milky-blue flowers
矢车菊。
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                                        bluetn.矢车菊 
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                                        blueadj.蓝色的;天蓝的;蔚蓝的;悲伤的;沮丧的;色情的;淫秽的;保守的;守旧的;青紫色的 
"early 18th cent.:  from French, diminutive of