菜心，英文翻译为 "Choy sum", 拉丁学名: Brassica rapa var. parachinensis 或 Brassica chinensis var. parachinensis ，为蔬菜物种之一，为中国人经常食用的蔬菜物种，特征是为茎部绿色，有细小的菜叶，叶片为深绿色，而叶片间有黄色的小花，是一个单独的品种。

由于西方人一向不太懂得分辨菜心与白菜等作物，在名称上经常把各种菜搞混，直到因为各地对亚洲菜蔬的输入量大增，才开始为各种菜蔬作详细及严谨的分类。

在广东省增城出产的迟菜心（又称高脚菜心）亦是菜心的一种，较一般菜心大棵和较甜。因其产于冬季，产时较一般的菜心晚而得名。可清炒或跟鲫鱼一起滚汤。

Choy sum (also spelled choi sum) is a leafy vegetable commonly used in Chinese cuisine. It is a member of the Brassica genus and the Brassicaceae (mustard) family (Brassica rapa var. parachinensis or Brassica chinensis var. parachinensis). Choy sum is a transliteration of the Cantonese name (Chinese:菜心), which can be literally translated as "vegetable stem". It is also known as Chinese Flowering Cabbage.