What does the woodspurge symbolize in the poem?

Literary critics have come up with many possibilities for what the woodspurge might symbolize in Rossetti's poem. Some believe that the woodspurge is not a symbol for anything at all; because the speaker cannot find meaning in the face of his "perfect grief," he must observe the woodspurge as an ordinary object. In this reading, the speaker latches on to the woodspurge because of its tangible ordinariness—the object itself is arbitrary, and it could have been anything else that caught the speaker's attention (such as a different plant, a windowpane, a random object, etc).

Despite this, there are still several readings of "The Woodspurge" that sense that there is a symbolic element in the speaker's description of the plant. A more controversial reading of the plant's symbolism suggests that it stands for Christianity. St. Patrick described the Holy Trinity using a three-leaf clover: like the clover, the Holy Trinity is one being that is made up of three separate parts. The same might be said of the woodspurge, and the speaker seems to be caught off guard by this fact. The only instance of repetition in the poem is a description of the woodspurge's floral quality: "the woodspurge flower'd, three cups in one" (14), and "the woodspurge has a cup in three" (16).