My heart is like a singing bird
Whose nest is in a watered shoot:
My heart is like an apple-tree
Whose boughs are bent with thick-set fruit;
My heart is like a rainbow shell
That paddles in a halcyon sea;
My heart is gladder than all these
Because my love is come to me.
Raise me a dais of silk and down;
Hang it with vair and purple dyes;
Carve it in doves and pomegranates,
And peacocks with a hundred eyes;
Work it in gold and silver grapes,
In leaves and silver fleur-de-lys;
Because the birthday of my life
Is come; my love is come to me.
This poem seems at first fairly straightforward in its ecstatic celebration of new love, a love so overwhelming that it marks the beginning of the speaker's real life – her "birthday." Note how each line is a separate grammatical unit, usually a comparison or command followed by a separate clause extending the simile or command, until the the final line, when the enjambment (the grammatical break over the lines) gives the effect of the speaker's emotion bursting forth, breaking through the balanced lines that preceded it. Many of those lines are references to the natural world, but they are also dense with Biblical, classical, and heraldic references and language, as if the entire world, natural and civilized, had to be brought in to convey the speaker's emotion.
Some explications: I take "a watered shoot" to be a young tree by a lake or river, fresh and green and everything a bird would want for its home. Vair refers to fur from a variety of the Eurasian Red Squirrel whose winter coat was bluish-grey on top and white underneath; in the Middle Ages it was stylish for aristocrats to line their mantles with alternating blue-grey and white skins, a fashion so popular that an alternating pattern of blue and white shapes was used in Heraldry and also called Vair. The "purple dyes" are a reference to Tyrian/imperial purple, an anciently-used natural dye derived from the Murex, a type of sea snail. Due to its great cost and high quality, it was favored by royal families in the Mediterranean around the time of the Roman Empire.
The peacock with "a hundred eyes" is a reference to Argus, the giant with a hundred eyes whom Hera ordered to watch Io, whom she had transformed into a heifer (both the transformation and the watchman were to keep Zeus away from the girl). When Zeus had Mercury kill Argus, Hera honored her servant by transforming him into a peacock (the spots on the bird's spectacular tail are the "hundred eyes"). The story is found in Ovid's Metamorphoses, as is the story of Alcyone, daughter of Aeolus ruler of the Winds, who married the mortal king Ceyx. When he drowned, she in her grief threw herself into the sea, where she was transformed into a bird who allegedly nests on the water – the story is that the seas are calm on the days she is nesting; hence "halcyon days."
The reason I said above is that the poem "seems at first" fairly straightforward is that on closer examination there is a disturbing pattern in her comparisons, a surprising number of which are linked in symbolism or origin with suffering and tragedy, in ways a writer like Rossetti would surely have been conscious of: the apple is traditionally considered the forbidden fruit Adam and Eve ate, resulting in their expulsion from Eden; a few chapters later in Genesis, the rainbow is the sign God gives Noah after the cataclysmic flood, offering the less than reassuring assurance that next time He will destroy the world with something other than water (as the spiritual has it, "No more water – the fire next time!"); as noted above, "halcyon" comes from a myth about suicide based on the death of a loved one; the pomegranate is the fruit of which Persephone, held captive in the Underworld, ate three seeds, with the result that for part of every year she must descend back to the Kingdom of her captor; as also noted above, the peacock (which is also a traditional symbol of vanity) is linked to a myth about adultery and love-suffering; the fleur-de-lys is the traditional symbol of the French monarchy, which had been violently cut off in the French Revolution a few decades before Rossetti's birth.
Certainly the images are all beautiful and apt and luxurious, and no real sense of foreboding attaches to such images as "my heart is like a singing bird." Perhaps Rossetti simply thought the apple-tree the most beautiful of the fruit trees in England, or the only one likely to have fruit heavy and plentiful enough to bend the bough. Yet there do seem to be enough images tinged with doom, enough of a repeated pattern, to give the reader pause. Are these things just unavoidable but random associations because language is slippery like that? Or is the implication that in this world everything, no matter how beautiful or glorious, is linked with suffering and death? Is she warning us that ecstasy is always shadowed with tragedy?
I took this from my copy of Christina Rossetti's Selected Poems, edited by C H Sisson, but I imagine any collection of her work would include this poem.