20 A UNIT IN AGRICULTURE 



II. Propagation Other Than by Seeds. Ex. 32. 



1. Spores mushrooms, ferns. 



2. Root stocks iris, calamus, June grass. 



3. Stolons or runners strawberry. 



4. Suckers or root stalks blackberry. 



5. Bulbs or corms onion, crocus. 



6. Tubers Irish potato, artichoke. 



7. Cuttings grape, currant. 



8. Grafts apple, pear. 



9. Layers grape, ornamental vines. 



Exs. 33, 34, 35, 36, 37. 

 Literature. 



Plant Propagation, Pub. School Bulletin, No. 1, pub. by Univcr 



sity of Missouri. 

 Farmers' Bulletin, Xo. 157. 

 Bailey, Nursery Book. 



D. PLANT GROWTH. 



t. Conditions of plant growth. 



(a) Plant food. 



(b) Moisture. 



(c) Heat. 



(d) Air. 



(e) Light. 



Exs. 38, 39, 40. 



2. Principal elements of plant food : oxygen, hydrogen, nitrogen, 



carbon, sulphur, phosphorous, potassium, calcium, 

 magnesium, iron. 



3. Air-derived elements: oxygen, hydrogen, nitrogen, carbon. 



Kxs. 11. I-.'. i:>. II. (See any elementary chemistry 

 forO., X.. II.. C(X.) 



4. Soil-derived elements: nitrogen, phosphorus, potassium, mag- 



nesium, iron, sulphur. Ex. 45. 



