52885
This motion is named after the botanist Robert Brown , who first described the phenomenon in 1827 , while looking through a microscope at pollen of the plant " Clarkia pulchella " immersed in water .
 Robert Brown, Clarkia pulchella
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Robert Brown, Clarkia pulchella