Bonta's poem opens with a riddle that works only if you know a little English history. "Thorn begins with thorn": the word starts with the letter þ, the Old English character that stood for the "th" sound before it dropped out of the alphabet. He calls it "a dead letter," a phrase that usually means an undeliverable piece of mail or a law nobody enforces. Yet the letter isn't really gone, because every "th" we say still carries its sound. Before a single plant appears, the poem has shown us something that ought to have vanished and still pricks.
From there the metaphors turn physical and increasingly uncomfortable. A thorn is "an aborted branch," growth cut off before it became a limb, and then, startlingly, "a weaponized nipple." That second image is the boldest in the poem. A nipple exists to feed, but this one "draws blood / instead of expressing sap." The verb "expressing" does double duty. It means pressing out a liquid, as milk is expressed, and it also means saying something. The thorn can neither give nor speak, only wound. The line break leaves "Mother" alone at the end of a line, right after the nipple, so the maternal picture stays in view as the poem moves on to "Mother / Nature red in tooth & claw."
That last phrase comes from Tennyson's *In Memoriam*, where it pictures nature as violent and indifferent. Bonta drops it in with a casual ampersand, as though it were the stock wisdom about thorns that he is about to quietly question. Even here the poem won't stay with violence for long. "Rose-hipped or hawed" names the fruits of the rose and the hawthorn, so the thorny plants are also the ones that ripen and feed. (Strictly speaking, botanists call a rose's spikes prickles and keep "thorn" for plants like hawthorn, so pairing the two lets the poem cover both.)
Then comes the turn: "But of course it doesn't bother the bees." The offhand "of course" makes the grim cosmic language sound like a human habit of seeing. The poem ends on a question: "for who needs a needle / to thread the seamless labyrinth / of the rose?" The thorn has been a branch, a nipple and a weapon, and now it becomes a sewing tool nobody needs. A needle is for joining seams, and the rose has none. Its folded petals form a maze, but a bee moves through it without a fight. One reading is that the bee, which has its own sting, simply doesn't meet the thorn as an enemy. The thorn only threatens those who come to take.
The form suits this shift. The poem is a single stanza of twelve lines, with no regular rhyme and no fixed metre, and its short lines sound like someone thinking aloud. Sentences slide over the line ends, and "from" hangs awkwardly at the end of the third line before the Old English alphabet is revealed. The sound patterns are subtle but deliberate. Hard *b*s pop through the middle ("begins," "branch," "blood," "bother," "bees"), almost like small pricks. "Needs a needle" turns on a repeated sound. And the lost letter hides in the sound of "Mother," "bother," "tooth" and "thread," so the dead letter keeps surfacing in the poem's own music.
The poem is worth reading because it starts from a single word and finds a whole argument inside it. The thorn is both a dead letter and an aborted branch, two things that failed to continue, and both still do some work. By setting a famous line about nature's cruelty beside the easy passage of the bees, the poem suggests that a thorn's violence depends on who is looking. It also shows how much a short, plain-spoken poem can pack into twelve lines, which is a good reason to slow down over every word.