274 Principles of Plant Culture. 



been pricked off, and compare their roots with those of 

 others that have not been pricked off. 



Relation of roots to food supply (112). Plant seeds of the 

 radish in saucers containing clean sand and potting soil 

 respectively, and when the seedlings have attained some 

 size, wash out and examine the toots in the two soils. 



Root tubercles (113). Study the roots of young clover 

 plants of various ages, and note how early in the devel- 

 opment of the plant the tubercles are discernible. 



I'ndergrouud siems (115). Study the development of 

 the potato plant from growing specimens, noting the 

 points at which the tuber-bearing stems originate, and 

 the marked difference between these and the roots. 



Nodes and internodes (116). Observe the nodes in the 

 stems of many plants, noting the relation of the diameter 

 of the young stem to the length of the internodes; also note 

 the undeveloped internodes near the terminus of the stem. 



Buds (128). Study specimens of leaf- buds from many 

 plants, noting their structure, position etc. 



Flower -buds (133). Study the form and location of the 

 flower-buds in many plants, particularly in fruit trees. 



Parts of the flower ( 141 ) . Study the parts of the flower, 

 explaining the function of each part. 



Perfect and imperfect flowers (154). Study these as pro- 

 duced .by several different plants, particularly of the 

 strawberry. 



Degree of maturity necessary to germination (163). Test 

 seeds of Indian corn, pea, tomato etc., that were gathered 

 at varying stages of maturity. 



Seed vitality limited by age (165). Test seeds of lettuce, 

 parsnip, onion etc., 1 year, 2 years and 5 years old re- 

 spectively. 



Stratification of seeds (170). Perform the process, as 

 described, in boxes or large flower* pots. 



Sun-scald (186). Eequire each student to make a lath 

 tree protector (Fig. 59). 



Winter protection of plants (202). Protect half-hardy 

 shrubs by wrapping them with straw or covering them 

 with earth. 



Foretelling frost (207). Devote an exercise to the use of 

 the psychrometer and the computation of the dew point. 



