What emotions do the images starting in line 19 of "The Guitar" ("Hot southern sands") convey to the reader? What theme or message is Lorca making in this poem?

Lorca's poem "The Guitar" is meant to imitate the sounds of a guitar and to use that sound and the image of a guitar to evoke the way in which life does not always fulfill one's hopes and yearnings. The poem presents a series of images that metaphorically represent the ways in which the guitar cries for what it cannot have but desperately wants. 
Lines 19-20 begin a series of images and metaphors about what the guitar cries for. These lines read, "Hot southern sands/ yearning for white camellias." This image is of a desert that yearns for lush flowers. Later lines present other objects yearning for what they cannot have, such as an arrow crying for a target, evening yearning for morning, and a bird that dies on the branch. The bird, a symbol of innocence, meets death instead of enjoying life. Then, Lorca compares a guitar to a heart that is hurt by "five swords," or the five fingers that play it. While the guitar wails for things it cannot have, it must suffer being wounded by five fingers. The emotions conveyed in these lines are suffering that arises from unrequited hopes, and the theme of the poem is that life is filled with this type of mournful longing.