Acis autumnalis - A Grower´s Guide

Jan 21, 2012
Peter Ashby

Acis autumnalis var. oporanthus - Peter Ashby

Confusion reigns in the classification of this little plant, but it still manages to hold its dainty white Autumn bells high to charm all who see it.

In the gardening world, drifts of diminutive snowy white blooms are usually associated with the appearance in early Spring of Galanthus, better known as the snowdrops. No other bulbous plant is so intimately associated with the last throes of winter and as a harbinger of better times to come.

As Summer gradually declines towards the season of fruits and falling leaves, a close relative of the snowdrops puts on a surprising and often prolific show of dazzling white bells, a charming display that remains inexplicably rare in the temperate garden. This little plant, with its nodding, crystalline white elfin bells, is Acis autumnalis (formerly Leucojum autumnale) sometimes known as the Autumn snowflake.

Snowflakes and Snowdrops

Over the last 200 years, the genus Acis has, on more than one occasion, been a victim of those confusing taxonomic "spring cleans" that shift familiar species into strange and obscure new groupings.

In the case of Acis, this genus was first created in 1807, but was then combined with another closely-related genus Leucojum. Finally, in 2004, genetic research showed that Leucojum, (the Spring and Summer snowflakes) was a distinct genus of only two species and that the nine species of Acis were in fact an exclusive group after all.

In practical terms, the Autumn snowflakes are not as closely related to Galanthus, the familiar snowdrops, as are the two species of Leucojum. While snowdrops have three conspicuous outer tepals (the generic term for sepals and petals) and three smaller inner tepals often marked with green, Autumn snowflakes have six regular, unmarked tepals. The two species of Leucojum likewise have bell-shaped flowers with similar tepals but these have markings akin to those of snowdrops.

Another difference is that Acis have linear or grassy foliage rather than the broader leaves of their relatives.

September Snow

From amidst all this confusion, the dainty bells of the Autumn snowflake emerge in late August and September to brighten hillsides and woodlands in Portugal, Spain and Morocco. The flowers usually emerge before the leaves and are held, two or three at a time, on slender purple stems that can reach 20 cm in height but are frequently shorter.

The flowers have a pure and sparkling quality as if the petals were infused with tiny crystals and, in some forms, are gently infused with pink. At this point, Acis autumnalis once again takes a trip through the labyrinth of nomenclature because the two North African variations - var. pulchella which carries leaves and flowers at the same time, and var. operanthum with taller stems and more arching pedicels - are now considered to be merely forms rather than distinct varieties.

Narrow leaves are produced with or after the flowers: these persist throughout the winter and fade as the bulbs head into their summer dormancy.

Cultivation

Most Acis appreciate a hotter, drier summer rest than Leucojum and Galanthus, but Acis autumnalis is a little more flexible in its likes and dislikes and can be grown in a range of soil types and situations, from raised beds and rockeries to permanently moist ground.

In general, providing a freely draining gritty medium and a sunny location is likely to meet with the best results. Although delicate in appearance, this plant is reasonably hardy and if happy, will form sizable colonies via offsets and seed.

It is also an exceptional bulb for pots and some growers achieve better results with container culture than in the open garden.

Propagation

As mentioned already, Acis autumnalis multiplies easily by way of offsets to create compact colonies with multiple flowering stems. It is a simple matter to divide these clumps either after flowering or when the bulbs are dormant.

Plants frequently self-seed and increase in this way without human intervention. If desired, the small seeds can be collected and sown fresh on the surface of gritty compost, covered with several millimetres of silver sand or fine grit, and germinated in a cold greenhouse.

Given thesimplicity of cultivation, it is a wonder thatAcis autumnalis is not better known. The related snowdrops have in recent years attracted an almost fanatical following of devotees, and these "galanthophiles" often maintain dozens of species and varieties in their collections. Perhaps it is time for the nine or so Acis species to emerge from obscurity and enjoy their time in the Autumn sun of popularity too.