In article ,
Radium wrote:
If you mean, do plants get cancer,

Yes. I meant to ask if plants can get cancer on their own. Just like
humans and animals. Virus infection? In theory, any cell [plant,
animal, fungi, algae etc.] constantly irritated by viral enzymes could
undergoes some mutation. Right?

Look up Agrobacterium tumifaciens (I probably spelled that wrong). It
causes plant tumors, and the tumor producing genes get incorporated into
the chromosomes of the host. There are a number of other organisms that
cause plants to produce "tumors", including some insects that induce galls.
Fungi and nematodes induce lumpos on roots in "root knot" disease, and
notrogen fixing bacteria induce similar root nodules. Often it's done
by secreting plant hormones.

It's hard to decide what a cancer would be like in a plant. Plants don't
have fixed forms like most animals do, and they normally have embryonic
cells all the time. They also lack a circulatory system that can transport
cells.

BTW, I have notice some abnormally bright green spots in my tulip
petals. They are supposed to be yellow, not green. Could this be due
to viral infection of chloroplasts in cells of the "blood green"
region's of the tulip's petals?

It could be. Or it could be from fungal or insect damage. The petals are
green to start with, and local damage might prevent a patch of tissue from
maturing properly. There's a group of tulip cultivars called viridifloras
that retain green color in parts of the petals as a genetic trait.

You sound like an observant person with an inquiring mind. There are all
kinds of interesting things to be observed with plants. Every year or
two I find an orange in the store with a somatic mutation that makes the
skin much thinner or thicker over a quarter section of the surface. I
once found an onion plant among the normal ones that had longitudinal
yellow stripes on the leaves. This was probably due to the kind of
viral infection you are thinking of (the yellow stripes, not the green
ones). I wanted to see if it might be genetic instead, but the plant
was quite weak and didn't survive to set seed.