Zea mays

Vacuole An organelle bounded by rhe tonoplast and
containing a watery fluid. During differentiation the
many small vacuoles of the meristematic cell become
confluent and expand to form a large central vacuole.
Variegated leaf A leaf showing a distinct pattern of
green and lighter or white regions in the leaf blade;
commonly formed from a varigatcd chimaeral shoot
apex.
Vascular bundle A strand of tissue composed of
primary xylem and phloem (and in dicotyledons
cambium) running lengthwise in the shoot.
Vasculi1r cambium See cambium.
Vascular tissue A general tcrm referring to both the
xylem and phloem.
Vegetative cdl In £lowering plants this is the largest of
the two cells in the young pollen grain.
Vdaml!n The water-absorptive multiple epidermis in
the roots of tropical epiphytic orchids and on some
aroicis.
Venation The panern formed by the veins supplying
the leaf blade.
Vessel A long, perforate rracheary clement, formed
from a Jongirudinal series of cells by the breakdown of
their cnd wall (see perforation plates). The pattern of
secondary wall deposition is variable (d., rracheary
element).
Wood The secondary xylem of arborescent dicoty·
ledons and of gymnosperms.
Xeromorphic .\10rphological features typical of xerophytes.
Xerophyte A plant of dry regions with various xeromorphic
features such as hairy and inrolled lea\'es, thick
cuticles, sunken stomata, or spiny reduced leaves with
succulent photosyntheric stems.
Xylem A complex tissue composed of the water
conducting uacheary elements, sclerenchyma and
parenchyma.
Zygomorphic flower A flower with bilateral symmetry.
Zygote The diploid cell resulting from the fertilisation
of a haploid egg cell by a male gamete; subsequent
division of the lygOte leads to the fonnarion of the proembryo.
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