Symbolism, Imagery, Allegory
Since he's so concerned with keeping the Logan land, it's not surprising that Papa comes up with a fitting metaphor for the family's relationship to it: the fig tree.
He describes it as having "roots that run deep," and no matter the hardships it faces (like taller trees that steal its sunlight), it "keeps on blooming, bearing good fruit year after year" (9.91). This fig tree symbolizes the Logan family and its relationship with the land. It keeps persisting (just like them), setting down roots in the area (again, like the family), and producing generation after generation of "fruit" that will tenaciously never give up.