Are Ipomea tricolor and I. caerulea synonyms? If not, any tips for telling them apart? - Ian.
I will proceed on the basis that the starting point is the accepted species binomial of of Ipomoea tricolor (Cav).
Ipomoea tricolor has several synonyms including :
Ipomoea rubrocaerulea (Hooker) - sometimes spelled as I.rubro-caerulea
caerulea is a variant spelling of coerulea which in botanical latin = dark blue
Ipomoea caerulea (Bello)
Ipomoea caerulea (Koen)
are both unresolved names at this point and are thought to refer to a plant that occurs in the Caribbean, most likely I.hederacea but the matter remains to be officially clarified.
Ipomoea caerulea / coerulea is often used as a synonym of Ipomoea tricolor although technically it shouldn't be.
A google image search using any of the binomials I cited will pull up images of a variety of different species , further indicating that many people (including 'professionals' who should know better) are using the binomials somewhat indiscriminately and perpetuating confusion.
The other aspect that adds to the confusion is that many people think that in botany using a synonym = "exactly the same as" and this is most definitely NOT the case , as a synonym refers to the older no longer accepted binomial whereas there is only ONE current accepted name.
A plant species can have many different common names but only ONE Internationally accepted Botanical name.
There is a very good reason to try and use the current accepted name because there is only ONE per plant species which definitely helps to strictly identify a particular plant species.
I can help you to identify whatever plants you may have within Convolvulaceae if you post or send me photos of the parts that help ascertain the identity such as flowers (both frontal and side views showing the calyx) ,and very important are clear closeup photos of the sepals on the base of the flower and any seedpods , whether still green and / or when almost ripe and / or fully ripe.
I know it may be a bit 'much' , but it is the only way to know for sure what species you are addressing.
Please let me know if I can be of further assistance.