Plants do not need a specialised transport system for oxygen and carbon dioxide because they have adaptations that give a high surface area: volume ratio for gas absorption and diffusion, leaves and stems have chloroplasts that produce oxygen and use up carbon dioxide, and plant tissues have a low metabolic rate
Mature xylem tissue is dead, so there is no evidence of organelles, and they have lignified cell walls, whereas sieve tube elements have no lignin, do have sieve plates, and their companion cells contain nuclei and dense cytoplasm
Vascular system with xylem (transports water and mineral ions from the roots to the rest of the plant) and phloem (transports substances from the source (eg. leaf) to the sink (eg.root))
Vascular bundles contain xylem and phloem arranged together
Plants must take in a constant supply of water and dissolved minerals to compensate for the continuous loss of water via transpiration in the leaves, and so that they can photosynthesise and produce proteins