446 TEXTBOOK OF BOTANY 



Integument. The layer, or one of the layers, of tissue surrounding the 



ovule, which develops into the seed coat or coats. 

 Internode. The parts of a stem or branch between two successive 



joints or nodes. 



Keel. The two lower (usually united) petals of the flowers of most of 

 the members of the pulse family. 



Lenticel. An opening in the bark of a woody plant, through which the 

 gases of the air may reach the inner tissues. 



Macrospore. The larger kind of spore of a plant which produces 



spores of two kinds. 

 Macrospore sac. A structure in which macrospores are produced ; in 



seed plants, the same as the ovule. 

 Medullary rays. Radial rows or layers of thin-walled cells, cutting 



through the wood or bast of a gymnosperm or dicotyledon. 

 Micropyle. An opening through the integument or seed coat. 

 Microspore. The smaller kind of spore of a plant which produces two 



kinds ; in seed plants, the young pollen grain. 

 Microspore sac. A cavity in which microspores are produced. In 



seed plants, the same as a pollen sac. 



Nectar. A fluid, commonly sweet, secreted usually in some part of 



the flower for the attraction of insects. 

 Node. One of the joints of a stem or branch, at which a leaf or leaves 



arise. 

 Nucleole. A small, usually rounded body lying within a nucleus. 

 Nucleus. A definite portion or organ of a living cell bounded by a 



membrane ; distinguished from the cytoplasm. 

 Nutation. The movement in a more or less nearly spiral direction of the 



end of a stem or branch, due to unequal rates of growth on different 



sides. 



Opposite leaves. Those of which two are borne, opposite each other, at 



the same node of a stem or branch. 

 Order. A group of related families. 

 Organic. Belonging to, or produced by, an organism. 

 Organism. A living being — plant or animal. 

 Ovary. The lower part of a pistil, containing one or more cavities in 



which an ovule (macrospore sac) or ovules are borne. 

 Ovule. The macrospore sac of a seed plant ; a small body which may 



develop into a seed. 



