Underside of the needles of the Eastern Hemlock, <i>Tsuga canadensis</i>. Note the two pale white lines.
<a href="//commons.wikimedia.org/wiki/User:Sdetwiler" title="User:Sdetwiler">Sdetwiler</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>