Like tall nettles, thistles, takes ideas about life from nature. The defiant character of the plant is emphasized in the very first word ("Against") of this poem. They not only resist all animal ("rubber tongues of cows") and human ("hoeing hands of men") attempts to destroy them but even attack the natural world, indicated by the words "spike the summer air". Further, they make it difficult for themselves to reproduce because their seed-pods open only …showed first 75 words of 830 total…

…showed last 75 words of 830 total…short second line of the first stanza and the first like of the second, is effective in suggesting the abrupt and violent nature of thistles. The poem slows and becomes jerky, and simpler, in the last stanza, as if with exhaustion, and so conveys a sense that the thistles are dying. Half of the last stanza refers to the "sons" and gives a clear sense if the cycle having begun again, and will continue endlessly.