The following has been ascertained by several thousand years of research both empirical and theoretical but is by no means more authoritative than actual experience since The Rose is ever evolving as all Life
The black petals along with every color petal has its own internal/external function along with the abilities after refinement that have already been listed. Even for all the ingenuity and efficiency of the people of ELF the number of petals harvested each year by all of ELF's faculties the total number of petals harvested is far less than half of those absorbed within The Rose itself.
Among these functions the black is by far the most important. The black are the healing salve that not only heals the local deficiencies of The Rose from wounds to disease to creating a sort of energy reserve that is used to heal more isolated wounds or more especially severe wounds. Its external or aggressive function is as an acid that can burn through almost any material in Nationstates.
These abilities, like everything else with The Rose becomes more intensified as one nears a fertile area or near the "home" which is located in Petalopia. The acids breaks down all material which is then easier to pass into The Rose or of a material that is not absorbed to be collected into troves beneath the bed. These troves are an extremely valuable bonus to any who are able to scour out a bed, the more ancient the bed the greater chance for exceptionally valuable material to be found, if they haven't decomposed. However The Rose can assimilate most lighter elements so it is rare for any but the heavier elements to be found.
This yellow petal exudes a liquid that carries a bacterial agent. Those whose skin comes into contact will contract a contagion. This disease is fatal and extremely contagious for 36 hours. What affect it has on The Rose itself, if any, is unknown.
The blue petals are especially dangerous because the liquid has emotional enhancing qualities. These usually manifest in fear panic or more rarely berserk rage. Any internal use is unknown.
The red petals act as a corrosive element to non organic material. This causes the material to become exceptionally brittle. Contact with fumes from this petal cause blindness, deafness, vertigo & loss of smell. This liquid seems to be connected in some manner to The Rose's ability to sense their surroundings far beyond their immediate range. How is unknown.
The extremely rare white petals are an enigma. It is known in some way they interact with sentient minds allowing The Rose access in a variety of ways. It is unknown whether this is the internal or external function of the liquid or a combination. They are also believed to be connected in some way to the smart spores that deliver target specific payloads over long distances.
Little is known of the green petals though they are believed to initiate the spores that are shot high into space as well as used to create a sort f curtain that inhibits communications, electronics and has a decaying effect on localized magnetic fields. This has been conjectured in a highly controversial report issued from a joint study by ELF & The Confederacy.
The larger beds of petals have been known to have large tubelike vents. These are highly flexible allowing it to point in different directions. Through them these liquids can be expelled at great speed. One type of liquid might be exuded in this matter or any combination of liquids such as petals are available. If there are no yellow petals in the bed then the yellow liquid cannot be expelled.