whorled milkweed: milkweed of the eastern United States with narrow leaves in whorls and greenish-white flowers
milkweed: any of numerous plants of the genus Asclepias having milky juice and pods that split open releasing seeds with downy tufts
silicon carbide: an extremely hard blue-black crystalline compound (SiC) used as an abrasive and a heat refractory material; crystals of silicon carbide can be used as semiconductors