Genes:
Each of the units of heredity which are
transmitted from parent to offspring in
gametes, usually as part of a chromosome, and
control or determine a single characteristic in
the offspring.
[There are genes responsible for each feature
of your plant to be inherited, for leaf colour,
stem structure, texture, smell, potency, etc.]
Alleles:
Any of a number of alternative forms of one
gene.
[For example the Gene for purple bud colour may
have 2 forms, one for purple and one for dark
red.]
Homozygous:
An individual that has identical alleles at one
or more genetic loci, which is not a
heterozygote and so breeds true.
[Your plant is to be said homozygous for one
feature when it carries in its responsible gene
pair the same gene twice, which means both
genes of the gene pair are equal.]