hogweed vs purslane

hogweed

noun
  • Any coarse weedy herb. 

  • An umbelliferous plant, of genus Heracleum, most species of which are phototoxic. 

  • Certain plants from the genera Ambrosia, Erigeron, or Heracleum. 

purslane

noun
  • the widely-grown edible plant common purslane or summer purslane (Portulaca oleracea) 

  • pink purslane (Claytonia sibirica) 

  • Halimione portulacoides 

  • moss-rose purslane, moss rose (Portulaca grandiflora) 

  • shoreline purslane (Sesuvium portulacastrum) 

  • Honckenya peploides 

  • purslane tree (Portulacaria afra) 

  • winter purslane, miner's lettuce (Claytonia perfoliata) 

  • Any of the family Portulacaceae (order Caryophyllales) of succulent plants. 

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