[1] Hawkes explains this by the tradition that this type of orange tree is supposed to grow naturally only in the part of China of which the ancient land of Chu was included in (as opposed to the northern plain).
The word ju, meaning "orange (fruit or tree)" is phonetically reminiscent of the word zhù (祝), which means "to wish or pray for", as in the phrase zhù fú (祝福), "to wish or pray for good luck", thus the orange is symbolically a "harbinger of good luck".
In this case, the final syllable of each line is the exclamatory particle 兮 (xī).
The author is unknown, although as usual with the Chu ci pieces, Qu Yuan has been given attribution, although in this case, this is not to likely given the evidence of the advanced metrical style (Hawkes 1985, 178).
The final line of the poem makes an allusion to "Bo Yi", referring to the pair of brothers whose loyalty to the previous Shang dynasty resulted in that they preferred to starve to death than to symbolically submit to the succeeding Zhou dynasty by eating the produce of the land, which Zhou in their view had usurped from Shang.