root cap

基本解释

Both root and root cap are covered by a sheath-like structure called the coleorhiza .
根和根冠被一鞘状结构，即胚根鞘所覆盖。
translation-dictionary.net
Objective: To observe the effectiveness of foursquare coil cable root cap attachment system in removable partial dentures.
目的：探讨四角圈簧根帽附着体义齿的制作方法和临床应用。
If root cap was shaded when the root was irradiated, the root showed no negative phototropism' And the root lost the characteristics of negative phototropism when root cap was divested completely.
对根冠遮光而给根尖其他部分照光时，稻根不发生负向光性反应。

"It's so simple. With a two-liter bottle you add sugar, you add extract, you add a small amount of yeast and water, cap it up and in two days they've got root beer.

a hollow cone of loosely arranged cells that covers the growing tip of a root and protects it during its passage through the soil