Botanist studies the local population of the brightly-coloured sand crocuses that are starting to flower at this time of year, especially in rocky garigue areas

Romulea rollii is not found in Malta.

During the months of February and March, the Maltese countryside is adorned with white, lilac or, more commonly, violet, star-shaped flowers growing low, almost at ground level.

They are commonly called sand crocuses and their scientific genus name is romulea, derived from Romolus, which according to myth, was one of the twin brothers involved in Rome’s foundation. They belong to the family of irises and their centre of diversity is sub-Saharan Africa with nearly 80 species and the Mediterranean region, represented by some 15 species.

Sand crocuses are widespread throughout the Maltese islands with some species reported since the late 19th century. Until a few years ago, the sand crocuses were represented locally by four species, the branched sand crocus (Romulea ramiflora); Rolli’s sand crocus (Romulea rollii); the lesser sand crocus (Romulea columnae); and the Maltese sand crocus (Romulea melitensis).

The latter was a presumed endemic species described in 1905, but several attempts to find this plant according to its original description were futile, leaving the question of where or what is the Maltese sand crocus.

Romulea martynii, characterised by completely dark-violet underpetals.

I spent three years researching the sand crocuses of the Maltese islands and southern regions of Sicily, initially to find clues about the identity of the endemic Romulea melitensis.

I examined more than 400 plants in their fine details, including the pollen and leaf tissues. The results even surprised me as only the status of the lesser sand crocus – easily recognised from its petite whiteflowers – remained unchanged across the various species.

Most of the sand crocuses in Malta were represented by the branched sand crocus and Rolli’s sand crocuses. Both species are described to have lilac to violet flowers with a distinct yellow centre. However, the majority of the Maltese plants that were examined did not correspond to this description, since, among other differences, they had a whitish or pale green centre.

The variety mirandae, characterised by the completely pale green underpetals. These species are named after Mifsud’s brunette son and blonde daughter.

After having found Rolli’s sand crocus in vegetated sand dunes in Modica and the branched sand crocus in the damp coastal soil at Sampieri – both in Ragusa, Sicily – it was clear that the former species (Romulea rollii) does not occur in Malta, whereas the latter (Romulea ramiflora) was found only in few locations such as Binġemma and Mġarr ix-Xini.

The majority of the sand crocuses found locally were assumed to be the Maltese variant (Romulea melitensis), but they did not match with the historical description and type specimen of this species described by Augusto Beguinot (1875-1940), an Italian botanist who never visited Malta.

Two other varieties were named after my own children

His original description refers to plants forming deep violet flowers with a yellow centre and with very narrow, linear petals. The plants occurring frequently in Malta are different.

Garigue dominated by thyme in Comino in June 2012.

The white throat of Romulea variicolor, the variably-coloured sand crocus.

Further research in historical manuscripts revealed that even Beguinot was confused by our sand crocuses. He later redescribed the species to account for the white throat among other incongruences, but such practice is considered illegitimate by the International Code of Botanical Nomenclature which stipulates that two descriptions from two different plants cannot be merged into one species.

Consequently, these crocuses with white throats were named Romulea variicolor (the variably-coloured sand crocus).

Two extra varieties were named after my own children – mirandae, which has the lower side of petals completely white or green; and martynii, which instead has a completely dark violet colour.

Romulea variicolor, subendemic to Malta and south Sicily.

The variably-coloured sand crocus also occurs in small populations at Marina di Modica and Cava d’Aliga, discovered by Salvo Brullo (2009) and myself (2011, 2013) respectively. The status of this species is best defined as sub-endemic.

Concluding, the three sand crocuses present in Malta are the lesser sand crocus (Romulea columnae), which is frequent in pathways, footpaths and trampled areas; the branched sand crocus (Romulea ramiflora), which is rare and occurs in damp garigue areas; and the varied-coloured sand crocus (Romulea variicolor) which is common throughout the Maltese islands.

Hybrids between these species have already been observed and R. melitensis as described by Beguinot might in fact have been such a hybrid.

Stephen Mifsud studying sand crocuses in Cava d’Aliga in Sicily, where he found a new variety of Romulea variicolor.

The author is a qualified botanist working with EcoGozo Regional Directorate. He thanks the Davies Exploration Fund of Scotland for sponsoring a major part of the research, Mepa for supplying the permits and EcoGozo Regional Development Directorate (Ministry for Gozo) for additional research support.

• Any further questions about these sand crocuses may be sent by e-mail to Mr Mifsud on: info@maltawildplants.com.