924 



GLOSSARY. 



Variegation, a term employed to designate the dis- 

 position of two or more colours in the petals, leaves, 

 and other parts of plants. 



Vascular bundle, a continuous strand of vascular 

 tissue, consisting either of xylem or phloem, or 

 of both. Not infrequently sclerenchymatous ele- 

 ments are associated with the bundle, when it is 

 termed a fibro-vascular bundle. 



Vascular elements, cells or vessels whose main 

 function is the distribution of water or formed 

 food-substances. The chief of them are the vessels 

 and tracheids of the wood, and the sieve-tubes of 

 the pliloem. 



Velum, in Isoetes ; the indusium-like membrane 

 which covers the sporangium. 



Velum partiale, in Hjraienomycetes ; the veil 

 stretching from the stipe to the edge of the pileus. 

 It often remains as the annulus. 



Velum universale, in Hymenomycetes ; the mem- 

 branous wrapper inclosing the whole fructification. 



Venation, the arrangement or pattern of the vascular 



bundles in a leaf. 

 Ventral canal-cell, the small cell which is cut off 



from the central cell of an archegonium immediately 



below the neck. 



Ventricose, unequally swollen. 



Vernation, the arrangement of the parts in the bud, 

 especially a vegetative bud. 



Verrucosa, covered with warts. 



Versatile, turning freely on its support. 



Verticillate, arranged in a whorl. 



Vessel, a tube consisting of cells which have be- 

 come conüuent by the partial or complete absorption 



of the intervening walls. They are common in the 



wood of Angiosperms. 

 Viviparous, term applied to plants the seeds of 



which germinate whilst still on the parent plant. 

 Volva, same as vdum universale. 



Whorl, a series of appendages arranged in a circle 

 around an axis. 



Witches' Broom, a form of gall found on the Silver 

 Fir and other Conifers ; sometimes applied to the 

 bird's-nest-like hypertrophies on the Birch, &c. 



Wood, the hard, lignified portion of the vascular 

 tissue otherwise known as the xylem. It contains 

 tracheids, woody fibres, and wood parenchyma, 

 though not all of these are necessarily found in the 

 wood of any given plant. 



Xenogamy, pollination between flowers growing on 

 different individuals of the same species. 



Xylem, the woody portion of vascular tissue. See 

 Wood. 



Zoogloea, a solid gelatinous colony of Bacterial 

 organisms. 



Zygomorphic, applied to flowers which are symmet- 

 rical about one plane only, or can be cut into similar 

 halves in only one plane. 



Zygospore, a spore formed bj' t".ie union of two 

 gametes. 



Zygote, a general term for the product of fusion of 

 two gametes. 



Zygozoospore, the motile stage of a zygote, the 

 product of fusion of two motile gametes. 



