bead tree vs syringa

bead tree

noun
  • Melia azedarach, a deciduous or semi-evergreen tree with poisonous fruit, native to India, Southeast Asia, and northern Australia. 

syringa

noun
  • Any of several flowering plants, of the genus Syringa, such as the lilacs. 

  • Hence any of several flowering plants of the genus Philadelphus, such as now in the Western United States Philadelphus lewisii. 

How often have the words bead tree and syringa occurred in a corpus of books? (source: Google Ngram Viewer )