Appendix I 385 



Mulch. A loose covering of straw, leaves, or soil, to retard evapora- 

 tion from the soil. 



Nitrate. A compound having nitrogen trioxide (NO 3 ) combined with 

 a basic mineral substance; a salt of nitric acid, as Sodium nitrate. 



Nitrification. The changing of nitrogen into nitrates. 



Nitrite. A compound in which nitrogen dioxide (NO 2 ) is combined 

 with a base. 



Nitrogen. A gaseous chemical element composing 79 per cent of the 

 air. It forms a constituent of the more expensive mineral plant- 

 foods. A constituent of ammonia, albumen, proteids and all 

 living substances. 



Node. The place on a stem where the leaves and branches originate. 



Nutrient. A substance which serves as a food. 



Organic. Of or belonging to living things. Organic matter has been 

 formed from simple chemical compounds and exists in nature 

 only as formed by animals or plants. 



Osmosis. The movement of a liquid through a membrane. 



Ovary. The part of the pistil that bears the seeds. 



Ovule. The parts inside of the ovary that grow into seeds. 



Ornithology. Science of birds. 



Oxygen. A gaseous element composing about one-fifth of the air. 



Oxidation. Combining with oxygen, as in the rusting of iron, burn- 

 ing of wood. 



Parasite. Dependent plants or animals drawing their food from other 

 living plants or animals. Compare with Saprophyte. 



Pedigree. A record of one's ancestors. 



Perennial. Plants that live from year to year, as trees. 



Petal. Parts of the corolla of flowers. 



Phloem. That part of a stem through which the reserve food moves. 

 In plants with netted veined leaves it is just outside of the 

 cambium. 



Phosphate. A salt of phosphoric acid. The bones of animals and the 

 shells of oysters are composed of phosphates. 



Photosynthesis. Same as Carbon Assimilation. 



Physiology. The science that treats of the life processes. It treats 

 of organs and their uses. 



Pistil. The part of a flower containing the embryo seeds. 



Plumule. The shoot end of an embryo plant. 



Pollination. The act of carrying pollen from anther to stigma. It 

 is usually done by the wind or insects. 



