gases (CO2, O2, H2O): intercellular spaces

water: xylem

inorganic nutrients: xylem

organ compunds (mainly sugar, but including RNA, amino acids, hormones, nutrients in organic molecules): phloem

Challenge:

-water transport in xylem: transports hundreds of litres of water per day up to 100m high in thin capillaries (vessels, tracheids) with very high friction resistance

-organ, molecules in phloem: need to regulate, what, when, where to transport