Milkweed is a plant, common in North America. If you snap the stem, a bitter white juice comes out — that is why it has milk in the name. It is not a food plant for people; that juice can be unpleasant or harmful. Gardeners and nature teachers talk about it because monarch butterflies lay their eggs on it, and the caterpillars eat the leaves. Weed here just means a wild plant, not necessarily something ugly in your garden. In Taiwan you are more likely to meet the English word in a nature video or a reading passage than in the market.

馬利筋；乳草