PLATE 3 
A. —A flower head of true dandelion, Taraxacum officinale , broken open longi¬ 
tudinally to show the slightly discolored receptacle and seed bases. More than 
50 per cent of these seeds contained living Tylenchus dipsaci . 
B. —A single seed of T. officinale , from which two living Tylenchi were dis¬ 
sected. Note the seed proper, which was intact, and the normal pappus. 
C. —A young plant of Taraxacum officinale with three leaves showing typical 
Tylenchus deformities. 
D. —A dandelion plant sectioned longitudinally through the crown to show 
the developing flower heads. Note that when very small they are in the very 
heart of the plant, protected from ordinary mechanical injury, unquestionably, 
but ideally situated for infection by the stem nematode. 
