GLOSSARY 357 



Unisexual. Having only male or only female reproductive organs. 



Vein. One of the fibrovascular bundles of leaves or of any flat organ 

 of plants. 



Venation. The mode of vein distribution. 



Xerophyte. A plant capable of thriving under conditions of strongest 

 transpiration and with scanty water supply. 



Xylem (wood). The wood (inner) portion of the fibrovascular bundle. 



Zoospore (animal spore). A motile asexual spore. 



Zygomorphic. Said of a flower which can be bisected by only one 

 plane into similar halves, bilaterally symmetrical. 



Zygospore (yoke spore). The spore formed by conjugation of similar 

 gametes. 



