SEED DISPERSAL.

W. J. BEAL, M.S., PH.D.

GINN & COMPANY

PREFACE.

This little book is prepared with the thought of helping young botanists and teachers. Unless the reader has followed in detail, by actual experience, some of the modes of plant dispersion, he can have little idea of the fascination it affords, or the rich rewards in store for patient investigation.

A brief list of contributions to the subject is given; but, with very few exceptions, the statements here made, unless otherwise mentioned in the text, are the results of observations by the author.

I am under obligations for suggestions by my colleague, Prof. W. B. Barrows; my assistant, Prof. C. F. Wheeler; and a former instructor of botany, L. H. Dewey, now of the United States Department of Agriculture. B. O. Longyear, instructor in botany, with very few exceptions, has made the drawings.

  AGRICULTURAL COLLEGE, MICHIGAN.

CONTENTS.

CHAPTER I.—HOW ANIMALS GET ABOUT.

  1. Most of the larger animals move about freely
  2. Some animals catch rides in one way or another

CHAPTER II.—PLANTS SPREAD BY MEANS OF ROOTS.

  3. Fairy rings
  4. How nature plants lilies
  5. Roots hold plants erect like ropes to a mast
  6. How oaks creep about and multiply

CHAPTER III.—PLANTS MULTIPLY BY MEANS OF STEMS.

  7. Two grasses in fierce contention
  8. Runners establish new colonies
  9. Branches lean over and root in the soil
10. Living branches snap off and are carried by water or wind

CHAPTER IV.—WATER TRANSPORTATION OF PLANTS.

11. Some green buds and leaves float on water
12. Fleshy buds drop off and sprout in the mud
13. Seeds and fruits as boats and rafts
14. Bits of cork around the seeds prevent them from sinking
15. An air-tight sack buoys up seeds
16. Fruit of basswood as a sailboat, and a few others as adapted to the water

CHAPTER V.—SEEDS TRANSPORTED BY WIND.

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

CHAPTER VI.—PLANTS THAT SHOOT OFF THEIR SPORES OR SEEDS.

35. Dry pods twist as they split open and throw the seeds
36. A seed case that tears itself from its moorings

CHAPTER VII.—PLANTS THAT ARE CARRIED BY ANIMALS.

37. Squirrels leave nuts in queer places and plant some of them
38. Birds scatter nuts
39. Do birds digest all they eat?
40. Color, odor, and pleasant taste of fruits are advertisements
41. The meddlesome crow lends a hand
42. Ants distribute some kinds of seeds
43. Cattle carry away living plants and seeds
44. Water-fowl and muskrats carry seeds in mud
45. Why some seeds are sticky
46. Three devices of Virginia knotweed
47. Hooks rendered harmless till time of need
48. Diversity of devices in the rose family for seed sowing
49. Grouse, fox, and dog carry burs
50. Seeds enough and to spare

CHAPTER VIII.—MAN DISPERSES SEEDS AND PLANTS.

51. Burs stick to clothing
52. Man takes plants westward, though a few migrate eastward

CHAPTER IX.—SOME REASONS FOR PLANT MIGRATION.

53. Plants are not charitable beings
54. Plants migrate to improve their condition
55. Fruit grown in a new country is often fair
56. Much remains to be discovered


BIBLIOGRAPHY