Yeah, all green or vascular plants consume oxygen all the time. Green plant release oxygen through photosynthesis but they still consume oxygen at the same time. The primary way plants use oxygen is through their root cells. In order for a plant to take up water and nutrients from the soil, it must continually grow new root hairs. The cells that make up these hairs are living cells that do not carry out photosynthesis. They are similar to the cells of animals in that they require oxygen and give off carbon dioxide as they burn carbohydrates to obtain the energy they need to function. This is why you can "drown" a house plant by watering it too much. If the soil gets too saturated with water, the plants root cells can't get enough oxygen from the air. There are vascular plants such as cypress trees and cattails that are adapted to living in saturated soil. These plants have root hairs that grow out of the stems above the soil and/or water surface so that they can take in oxygen. When a plant is green, it is giving off more oxygen through photosynthesis in it's leaf and sometimes stem cells than it is consuming through it's root cells so that is why you hear people say thats plants are "opposite" of animals in that take in carbon dioxide and give off oxygen. When a plant is dormant and it's leaves have fallen off in the case of perennial decidious plants [as opposed to annuals such as dandilions or evergreen plants such as pine trees], then plants are still using oxygen and giving off carbon dioxide through there roots much stay active to keep the root crown from which the new stems and leaves will emerge the next growing season alive
