List of Illustrations 



Frontispiece, May-apple (Podophyllum peltatuni). 



FIG. PAGE 



i. Golden crocus (Crocus aurens), with analysis of the 



flower 20 



2a. Calyces of differing forms, Fox-glove, aconite, fuchsia, 



valerian, flax, and loose-strife 21 



zb. Corollas of various form. Tobacco-plant, lilac, sage, 



arbutus, pea, convolvulus, pink, and geranium 23 



3a. A pollen grain of the melon (much magnified) 24 



3^. Pollen grains of the European hazel (Corylus Avellana) 



putting forth their pollen tubes v . . . 26 



4. Florets and fruits of the dandelion 41 



5. Some altered calyces of composite flowers. Groundsel 



calyx altered into down. Bur marigold calyx altered 

 into prongs. Orange hawk-weed calyx altered into 

 bristles (all magnified) 46 



6. Fruit of the elm 50 



7. (a) Sleeping and (b) expanding buds of the horse-chest- 



nut 55 



8. Apple twig showing old bud-scale marks 58 



9. Blossoms of the butternut 67 



10. Blossoms of the oak (a) pistillate, (b) staminate 70 



11. Details of the blossoming butternut, (a) A cluster of 



pistillate flowers, (d) one stamen bearing scale de- 

 tached from the staminate flower-chain, (c) a single 

 stamen 72 



12. Buds of the ash 76 



13. Perfect (a) staminate (t>) and pistillate (c) flowers of the 



European ash (Fraxinus excelsior) 77 



14. Young horse-chestnut bur and young acorns 83 



15. Twinned fruit of the maple 85 



16. Magnified section of the green tissue of a leaf go 



xiii 



