Chapter 9: Terms
Apomixis | A form of clonal reproduction where vegetative cells in the flower develop into zygotes to form seeds. |
Carbohydrates | One of the three major types of nutrients found in seeds; provide energy in the form of starch and sugar. |
Coleoptile | Protective sheath that covers in the plumule and epicotyl in the Poaceae family. |
Coleorhiza | Protective sheath that covers the radicle in the Poaceae family. |
Cotyledon | Food storage structure used in germination. |
Dormant/dormancy | Term used when seeds are alive and don’t germinate when provided with favorable conditions for germination. |
Double fertilization | Where one haploid male sperm cell fuses with the female haploid egg cell to form the diploid zygote, and the second haploid male sperm cell fuses with two egg cells to form a triploid endosperm. |
Ecodormancy | When external factors, usually environmental, prevent a seed from germinating. |
Embryo | Nascent (new, young) plant resulting from the combination of genes from the male sperm transmitted by the pollen to the female egg held in an ovule in the ovary. |
Embryo axis | Embryonic root and shoot. |
Endodormancy | When internal factors within the seed prevent germination. |
Endosperm | Tissue that results from the second haploid male sperm cell fusing with two egg cells during fertilization. |
Genotype | Genetic composition of an organism. |
Lipids | Compact plant oils that store energy; also called triglycerides. |
Pericarp | Ripened ovary wall; made-up of three parts: exocarp, mesocarp, and endocarp. |
Phenotype | Physical appearance of an organism. |
Plumule | First true leaves of the plant; emerge from the seed, rise above the soil surface, and start to collect energy from the sun. |
Proteins | Sources of amino acids for production of enzymes and other nitrogen-rich compounds in the seed. |
Quiescent | When a seed does not germinate until given proper conditions for germination (oxygen, water, temperature, and sometimes light). |
Saturated fatty acids |
Fatty acids that have no double bonds in the chain with all carbon atoms in the interior of the chain having two attached hydrogen atoms. |
Scarification | Process used to break a physical seed dormancy (hard seed coat). |
Seed coat | Outer layer of the seed. |
Stratification | Process used to break a physiological dormancy, such as embryonic or endo/eco-dormancies. |
Triglycerides | Another name for lipids. |
Unsaturated fatty acids | Fatty acids that have one or more double bonds between one or more carbon atoms in the chain, lack some hydrogen atoms, and therefore the carbon atoms are not saturated with hydrogen. |