Cauliflower is a vegetable. It is a geosperm, which means it has seeds on the outside, not on the inside, like fruits.
A hemlock tree has naked seeds, meaning the seeds are not enclosed within a fruit or protective casing. The seeds are produced in small cones, typically found on the tips of the branches.
Yes, plants can survive without producing flowers. Many non-flowering plants such as ferns, mosses, and conifers are able to thrive and reproduce through other means like spores or cones. Flowering is just one method of reproduction for certain plants.