There may be fewer alpines that flower regularly in December in the northern hemisphere than in any other month, but Crocus laevigatus is one of the most reliable examples. In 'The Crocus', Brian Mathew says that it flowers from October to February, and I have certainly seen it in flower in the first week of November in southern Greece, but the variety fontaneyi which is most usually grown is invariably at its best with me around Christmas Day.
Crocus laevigatus is usually the latest to flower of three closely related autumn-flowering species confined to southern Greece and Crete. This group (series Laevigati) is characterised by white anthers and thread-like orange or yellow stigma branches which are divided several times. C. tournefortii from the Cyclades, Karpathos, Rhodes and the north-east coast of Crete has shallowly bowl-shaped bluish-lilac flowers which never shut, once open, while C. boryi from western and southern mainland Greece, the Ionian islands and extreme eastern Crete is usually white-flowered but rarely has the dark feathering on the outer perianth segments which is typical of many C. laevigatus. Both relatives are much larger than C. laevigatus, and lack the rather starry, romulea-like flowers of the latter. When repotting the corms, it will be observed that the corm tunics of C. laevigatus are smooth and rather shiny, hazel-nut like, but those of C. tournefortii and C. boryi have longitudinally fibrous corms. I have also noticed that in mixed populations of C. laevigatus and C. boryi on uplands near Lambokambos, and in the Monemvasia area of the south-eastern Peloponnesos that C. laevigatus has much shorter, fatter anthers compared to C. boryi, perhaps only half the length of those of the latter species. Although the two relatives are frequently found growing together, there is no indication that they hybridise, probably because they have different chromosome numbers (26 in C. laevigatus, 30 in C. boryi). However, Mathew suggests that C. boryi and C. tournefortii which share the same chromosome number hybridise (or at least merge into one another) in extreme eastern Crete.
In the southern Peloponnesos, C. laevigatus seems invariably to be white-flowered, and in some populations the flowers are innocent of dark marking. In others, many flowers have dark streaks on the outside of the outer tepals, a character which always seems to be absent in C. boryi. Sometimes there are just one or two small markings, but the marking (‘feathering’) can be conspicuous and beautiful. In these cases the flowers can resemble the yellow and black-anthered C. melantherus with which C. laevigatus also grows north of Sparti. However in the Cyclades, C. laevigatus is much more frequently lilac-flowered and nearly always has feathering outside. These populations are also later to flower, and some do not flower in cultivation until early spring. The popular lilac-flowered variety fontaneyi is almost certainly of Cycladian origin, and commences flower in the north of England in the last week of November, continuing into the New Year.
I grow C. laevigatus in crock pots plunged in sand in an unheated alpine house. Watering ceases when the foliage dies down in late April, and the corms are repotted into fresh soil in late July and from then on are kept slightly damp. In the early spring when they are in full growth they are sometimes given a liquid feed of ‘tomorite’. I find they increase quite well and flower reliably. Unlike many other crocus here, seed has never yet been set.