Source: Knapp, Alan. “Ranunculus ficaria subspecies.” Sussex Botanical Recording Society Newsletter, no. 65 (January 2008). http://sussexflora.org.uk/wp-content/uploads/2016/03/Newsletter_Jan_2008.pdf.
There are two common subspecies of Ranunculus ficaria (Lesser Celandine), Ranunculus ficaria subsp. ficaria and Ranunculus ficaria subsp. bulbilifer, and both occur widely in Sussex. They are differentiated by the presence, after flowering, of cream coloured tubers (sometimes referred to as bulbils) in the leaf axils of subsp. bulbilifer. Following a note about these subspecies in a recent BSBI News we checked our records and found that there were no records for Ranunculus ficaria subsp. bulbilifer before mid-April and the vast majority were recorded in May or early June. The reason for this is that the bulbils do not develop until the end of the flowering period.
Looking at the records for subsp. ficaria, it is clear that we have been recording it much too early in the year as there are many records for the period January to April. These records are invalid and we have removed them. The overall effect of this is that subsp. ficaria has been over-recorded and subsp. bulbilifer is probably under-recorded. Therefore we have two requests. Firstly, if you are recording R.ficaria before or during its flowering period and you cannot find the tubers, you should record it as Ranunculus ficaria with no subspecies (code 1649 on the recording cards). If you do find tubers then it’s okay to record subsp. bulbilifer at any time. To record subsp. ficaria reliably, you must wait until the flowers are going over and, if there are no tubers in the leaf axils, then you have subsp. ficaria. Secondly, as all records for Ranunculus ficaria subsp. ficaria with dates before mid April and records which only had a year as a date have been deleted, please look out for it again at the appropriate time of year and re-submit records. A map showing all the valid records is shown here and it is clear that there are now large areas with very few records. The species lists on the SBRS web site have also been updated to remove all early records.
Finally, remember that there are two other subspecies of Ranunculus ficaria: subsp. ficariiformis and subsp. chrysocephalus. The former has tubers like subsp. bulbilifer and occurs mainly in the far SW of England. It has never been found in Sussex. The latter is a rare garden escape. We have recent records from Fittleworth and Falmer but it might occur elsewhere so, if you see a very large flowered Lesser Celandine near habitation, take a close look and check carefully with the key in Stace.