Chapter V.--Seeds Transported by Wind.

17. How pigweeds get about . . . . . . . . . . . . . . . . . . . 30 18. Tumbleweeds . . . . . . . . . . . . . . . . . . . . . . . . 31 19. Thin, dry pods, twisted and bent, drift on the snow . . . . 35 20. Seeds found in melting snowdrifts . . . . . . . . . . . . . 36 21. Nuts of the basswood carried on the snow . . . . . . . . . . 37 22. Buttonwood balls . . . . . . . . . . . . . . . . . . . . . . 39 23. Seeds that tempt the wind by spreading their sails . . . . . 40 24. Why are some seeds so small? . . . . . . . . . . . . . . . . 42 25. Seeds with parachutes . . . . . . . . . . . . . . . . . . . 43 26. A study of the dandelion . . . . . . . . . . . . . . . . . . 44 27. How the lily sows its seeds . . . . . . . . . . . . . . . . 46 28. Large pods with small seeds to escape from small holes . . . 47 29. Seeds kept dry by an umbrella growing over them . . . . . . 48 30. Shot off by wind or animal . . . . . . . . . . . . . . . . . 50 31. Seed-like fruits moved about by twisting awns . . . . . . . 51 32. Grains that bore into sheep or dogs or the sand . . . . . . 51 33. Winged fruits and seeds fall with a whirl . . . . . . . . . 52 34. Plants which preserve a portion of their seeds for an emergency . . . . . . . . . . . . . . . . . . . . . . . . 54