Leucojum




		Taxonomy Leucojum aestivum (L.), Summer Snowflake, has enjoyed a stable taxononomic status, but in 1910 it was merged with L. pulchellum (Salisb.) creating two subspecies: L aestivum subsp. aestivum and L. aestivum subsp. pulchellum (Briq.) Chromosome No. 2n = 22 in both subspecies. The name Leucojum is derived from the Greek for ‘white violet.’ Several non-UK native members of the genus were split into a new genus, Acis, recently after genetic results showed greater differences than between Leucojum and Galanthus. Common names: Summer Snowflake; Loddon Lily (strictly only subsp. aestivum). Identification Leucojum is a genus in the Amaryllidoidae sub-family of the Liliaceae. These are bulbous plants with narrow leaves rising from the base of the plant. Flowers are solitary or in an umbel with a spathe at the base. The ovary is inferior. There is one stigma with a simple or three-lobed style. Some have a funnel-shaped corona within the tepals. Leucojum species have few or solitary flowers with all six tepals similar, hanging as a bell. Tepals are white with green or yellow patches. There is no corona. By contrast, Galanthus spp. (snowdrops) are distinguished by the inner three tepals forming a distinct bowl-shaped structure.

Distribution

Both sub-species may be found as escapes from cultivation but the more frequent sub-species in cultivation is L. aestivum subsp. pulchellum.

L. aestivum subsp. aestivum occurs in Ireland, The United Kingdom, Netherlands, Belgium, Germany, France, Switzerland, Italy, Austria, Yugoslavia, Albania, Greece, Czech Republic, Slovakia, Hungary, Romania, Bulgaria, Ukraine (SW and the Crimea), Turkey, Iran, Georgia, Russia (the Caucasus) (Fl. Europaea).

L. aestivum subsp. pulchellum is native to France (the Alps-Maritimes, Corsica), Spain (Balearic Islands), Italy (continent, Sardinia) (Fl. Europaea).

Ecology

L. aestivum subsp. aestivum occurs in wet meadows and Willow / Alder scrub by rivers in South England north to Oxfordshire.

L. aestivum subsp. pulchellum has become established in scattered communities (usually near water) through the British Isles from the Channel Isles north to Scotland but concentrated in the South of Britain and East Anglia.

Neither is represented in the National Vegetation Classification.

Status

Origin: L. aestivum subsp. aestivum is often considered native in some parts of the British Isles (Preston, Pearman & Dines 2002), but some botanists consider this to be rather dubious.

Rarity: neither subspecies is rare in Britain, although ssp. pulchellum appears to be rare in Ireland.

Threat: Leucojum aestivum is listed as ‘Least Concern’ in Cheffings & Farrell (2005), and in the New Atlas it is given a Change Index of +2.42, which shows a significant increase.

Conservation: The counties of Berkshire, Dorset and Co. Waterford all have Leucojum aestivum listed as an axiophyte, which means that the county recorders consider it to be indicative of good quality habitat.

Differences between the two subspecies

ssp. aestivum

No. of flowers (2-)3-5(-7)

Tepals larger: 13-22 mm

Spathe (bract behind flowers on stem) wide: 7-11 mm.

Flower stem edges rough - stems with the two sharp edges remotely and often inconspicuously denticulate, at least in lower half (Stace, 1997). (In practical fieldwork the distinction is easily made by gently running the fingers along the stem edges.)

Stem of Leucojum aestivum

ssp. pulchellum

Flowers (1-)2-4

Tepals smaller: 10-15 mm

Spathe narrow: 4-7 mm

Stem edges smooth (‘entire throughout’)

Stem of Leucojum pulchellum

> next species

Visit the Maps Scheme maps:-

>> Leucojum aestivum

Further work

The subspecies are often undifferentiated in records but are easy to distinguish once one has encountered each form. Recorders should be encouraged to make the distinction and to note any unusual habitat - particularly cases of long-established communities far from water. (The plant will survive well in drier condition in gardens - and can be seen at the top of a mound at Kew. It may be that water is more significant as a seed distribution medium than anything else.)

The supposed origin of British plants creates a curious dilemma. If there really is a small native population centred on central southern England, then it should be considered Nationally Scarce, and of considerable conservation importance. However, the lack of any such status reveals the lack of confidence botanists feel in this assessment. A study of its nativity and, if it is to be considered native, its ecology in the wild, is urgently required.

However, a non-native species that is increasing could just as easily be an axiophyte, if it tends to grow in good habitat and does not cause any harm. Such an understanding would be more sophisticated than the simplistic ‘native is good, alien is bad’ philosophy of the popular press.

References

Citation

Crellin, J.R. (Date accessed). Species account: Leucojum aestivum. Botanical Society of the British Isles, www.bsbi.org.uk.

Send us your comments and Feedback

John Richards (10/1/2010): Coming originally from Reading, where L. aestivum is invariably known as 'Loddon Lily', I am very surprised to learn that there should be any question as to its status, at least in the middle section of the Thames. Here it is more widespread than is generally recognised and is largely limited to a very distinctive habitat, mostly referable to W5b, which I call 'riverrein woodland', and which occurs besides the Thames and its tributaries, especially on islands ('eyots'), where willow/alder woodland is ungrazed, is frequently flooded in winter, has very wet mineral soils throughout the year, and posesses a very rich ground vegetation which becomes tall and dense in summer, but is open in April when the snowflake flowers. As this subspecies (aestivum) is also found in similar habitats in northern France. I think that 'The New Atlas' and Ian Taylor's commentary there has the distribution of native L. aestivum as a native plant exactly right.