78 THE HUMAN SIDE OF PLANTS 



it travels in the fall! Very true are the poet's 

 words: 



"A primrose by the river's brim, 

 A yellow primrose was to him 

 And it was nothing more!" 



There are plants which can tie sailor's knots! 

 The Virginia knotweed was skilled in this art long 

 before man had even heard of it. The knotweed 

 is a first cousin to the common knot-grass, and also 

 to the prince's-feather. The tiny flowers of the 

 knotweed are held on a long, club-like stalk, at the 

 base of which is a joint, that well represents a sail- 

 or's knot. When the seeds of this plant are ripe, 

 the pods containing them, which form the knots, dry 

 rapidly and shrink. As this shrinking continues, 

 the knot at last yields to the strain and snaps apart 

 hurling the seeds out and away, to germinate in 

 places far from the parent plant. This action is 

 much like the motion of the small boy with his 

 sling-shot. 



The capsules of several of the violets have a 

 strange, mechanical movement of the valves by 

 means of which they actually shoot their seeds, often 

 to a distance of several inches from the parent 

 plant. While the seeds are ripening, the pod droops 

 its head until it is hidden beneath the leaves; but, 

 as soon as the seeds are fully developed and ready 



