184 Minnesota Plant Life. 



an altogether dependent life-habit. A few definitions may not 

 here be ont of place and will be given in as untechnical language 

 as possible. 



Definitions of certain words. Pollen is a dust consisting of 

 small spores, capable, upon germination, of producing male 

 plants. The cwbryo-sac is a large-spore developed in the rudi- 

 mentary seed and capable of producing a female. The pollen- 

 spores are produced in special spore-cases situated on leaf-like 

 organs called stamens. The embryo-sacs are commonly pro- 

 duced singly in bodies called ovules borne upon leaves known 

 as carpels. An axis upon which stamens or carpels or both are 

 generated is called a Hoivcr. An ovule which has matured, 

 normally as the result of a breeding act, is called a seed. The 

 carpel, or carpels of a flower with the enclosed seeds, is called 

 a fruit. 



Two series of seed-producing plants. There are two series 

 of seed-producing plants, the lower, in which the pollen-spores 

 fall directly upon the immature seeds and germinate, and the 

 higher, in which the carpels close around the immature seeds 

 and the pollen-spores fall and germinate upon a special portion 

 of the carpel or carpels known as the stigma. 



