关于破折号的用法

NATHANCHING

求问各位大神，英语中破折号可以用来连接两个独立的句子吗？是的话为什么OG说下面这个句子un grammatical 呢：Grown from seeds saved during the previousyear, heirloom tomatoes appear less appetizing than most of their round and red supermarket cousins———they are often green and striped, or have plenty
of bumps and bruises—heirlooms are more flavorful and thus in increasing demand. 感谢！

GGininder

破折號是類似補充說明用法，所以破折號裡面可以是完整句子。
用法有點類似同位語的概念
這句當然是ungrammatical了