Acis is a genus of nine species of perennial, bulbous herbaceous plants belonging to the amaryllis family (Amaryllidaceae, subfamily Amaryllidoideae) and the order Asparagales. The genus is native to the western and central Mediterranean region, with species found across the Iberian Peninsula, southern France, Corsica, Sardinia, Morocco, and parts of Greece and Albania. Together with the closely related genus Leucojum, Acis plants are commonly known as snowflakes.
The flowers of Acis are distinguished by six equally sized, unmarked tepals — a key character that sets them apart from the related snowdrops (Galanthus), whose inner three tepals are shorter than the outer three, and from Leucojum, whose tepals bear coloured markings. Most Acis species bear white flowers, with the notable exception of Acis rosea, which has pale pink tepals. Plants are relatively compact, ranging from about 15 cm tall in Acis autumnalis to 45 cm in Acis tingitana. The leaves are narrow, and in Acis trichophylla they are extremely fine (filiform). The flower stalks (scapes) are solid, another distinguishing trait within the broader snowflake alliance.
The genus was first described by Richard Anthony Salisbury in The Paradisus Londinensis in 1807, when he separated it from Leucojum on the basis of differences he observed between Leucojum autumnale and Leucojum pulchellum. For most of the nineteenth and twentieth centuries, however, Acis was not widely accepted as a distinct genus, and its species were returned to Leucojum. The genus was formally reinstated in 2004, following morphological and molecular studies that demonstrated the broadly conceived Leucojum was paraphyletic, with Acis and a more narrowly defined Leucojum forming separate lineages. The name Acis was described by Salisbury only as a "poetic title" and may allude to the figure of Acis from Greek mythology.
Among the nine accepted species, Acis autumnalis is the most widely grown in cultivation and has received the Royal Horticultural Society's Award of Garden Merit.
Etymology
The genus name Acis was coined by the British botanist Richard Anthony Salisbury in 1807 when he established the genus in The Paradisus Londinensis. Salisbury offered no derivation beyond calling it a "poetic title"; it is generally thought to allude to Acis, the mortal youth of Greek mythology whose story is told in Ovid's Metamorphoses.
Distribution
Acis comprises nine species distributed across the western and central Mediterranean basin. Their collective range spans the Iberian Peninsula (Portugal and Spain), southern France (including the Nice region and areas around Mont Ventoux), Corsica, Sardinia, Morocco, and a disjunct population from SW Albania to western Greece. Individual species tend to have narrow, localised ranges — Acis nicaeensis, for example, is restricted to a small area of southeastern France east of Nice.
Taxonomy Notes
Acis was first segregated from Leucojum by Richard Anthony Salisbury in 1807, but the separation was not accepted by most subsequent botanists, and the species were subsumed back into a broadly defined Leucojum for most of the nineteenth and twentieth centuries. The genus was reinstated in 2004 after molecular and morphological analyses showed that the broad Leucojum was paraphyletic: Acis and a narrowly circumscribed Leucojum are sister groups, not a single natural lineage. The name Acis autumnalis itself was not published by Salisbury — it appeared in 1829 under Robert Sweet. GBIF places the genus in family Amaryllidaceae, order Asparagales.
Cultivation
Acis autumnalis is the species most commonly encountered in cultivation and has been awarded the Royal Horticultural Society's Award of Garden Merit, recognising its reliability and ornamental value. As Mediterranean bulbs, Acis species generally prefer well-drained soils and a sunny to lightly shaded position; the autumn-flowering species such as A. autumnalis thrive with a dry summer dormancy.
