cowslip vs swamp lily

cowslip

noun
  • A low-growing plant, Primula veris, with yellow flowers. 

  • Primula deorum, a flowering plant known as God's cowslip and rila cowslip 

  • Primula florindae, a flowering plant known as giant cowslip and Tibetan cowslip 

  • marsh marigold, Caltha palustris, a plant in the buttercup family, growing in wet, boggy locations. 

  • Pulmonaria angustifolia, blue cowslip or narrow-leaved lungwort 

  • Primula sikkimensis, a flowering plant known as Himalayan cowslip and Sikkim cowslip 

swamp lily

noun
  • Zephyranthes atamasco (rain lily, Atamasco lily) 

  • Ottelia ovalifolia 

  • Saururus spp. (lizard's tail) 

  • Any of various species of lily growing in wet habitats. 

  • Some species of Crinum, including Crinum americanum (southern swamplily), Crinum erubescens, Crinum pedunculatum (also river lily or mangrove lily) 

  • Lilium superbum (also Turk's cap lily, turban lily, lily royal, or American tiger lily) 

How often have the words cowslip and swamp lily occurred in a corpus of books? (source: Google Ngram Viewer )