Outside the large flower-head is a double row of small green leaves, which protected the tiny flowers within when the " head" was only a bud.

巨大的头状花序外面长有两排小绿叶, 它们“头状花序”只是蓓蕾时保护深藏中的幼年小花。

In this way the little yellow flowers that form the head are kept safe and warm till finer weather comes.

一来, 构成头状花序的黄色小花就得到了保护并且获得温暖, 直到天气情况有所好转。

Yes, and it was quite an innovation because the arrowheads they were using before were made of dandelion heads.

是的，确实是一次重大的创新，因为他们之前使用的箭头是由蒲公英的头状花序制成的。