GLOSSARY AKD INDEX. 287 



ventral, pertaining to the front ; opposed to dorsal, which see. 



vessels, tube-like structures composed of a succession of cells with vari- 

 ously thickened walls, belonging to the wood portion of iibro-vasoular 

 bundles, and usually continuous for long distances, 41. 



vexillum, the conspicuous upper petal of a papilionaceous flower, the 

 standard, 197. 



villose, covered with long, soft hairs, 58. 



vitta (pi. vittce), one of the oil-tubes of umbelliferous fruits, 226. 



whorled, arranged in a whorl or circle, 58. 

 wood, 41, 44, 54. 



xylem, the wood portion of a fibro-vascular bundle, as distinguished from 

 the phloem or bast. In gymnosperms and dicotyledons the xylem 

 portion of the bundles constitutes the wood-cylinder. 



zoospore, same as swarm-spore, 96. 



zygospore, a spore resulting from the union of two independent and 

 morphologically similar cells, 96, 102. 



