Tulip is the common name for any bulbous perennial plant in the Liliaceae flowering plant family's genus Tulipa, which contains thousands of varieties and about 100 species.
A bulb is a vertical underground shoot that has been modified (or thickened leaf bases).
As a modified stem with shortened internodes and bearing at its nodes and structures that may be highly modified leaves, the flower is viewed as such.
On a modified branch or axis with an apical meristem that does not grow continuously, a floral structure forms.
Thus we can say that tulip is a modified shoot because flower itself is a modified shoot.