|Flowers of Leucojum aestivum with female hairy-footed flower bee (Anthophora plumipes)|
Leucojum is a small genus of bulbous plants native to Eurasia belonging to the Amaryllis family, subfamily Amaryllidoideae. As currently circumscribed, the genus includes only two known species, most former species having been moved into the genus Acis. Both genera are known as snowflakes.
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The snowflakes are native to central and southern Europe, from the Pyrenees to Romania and western Russia, but they have been introduced and have naturalized in many other areas, including the east coast of North America. They have narrow, strap-like, dark green leaves. The flowers are small and bell-shaped, white with a green (or occasionally yellow) spot at the end of each tepal. They have a slight fragrance.
Leucojum vernum (spring snowflake) normally grows 15–20 cm (5.9–7.9 in) tall, though it may reach up to 35 cm (14 in). It flowers one or two weeks later than the snowdrops, i.e., from mid-February to March, as soon as the snow melts in its wild habitat.
Two varieties are known: L. vernum var. vernum with green spots on its tepals, and L. vernum var. carpathicum, which originates from the eastern part of its natural range, a larger plant with yellowish spots on its tepals; 'vagneri' from Hungary is a robust variant of var. vernum, often with two flowers per stem.
Leucojum aestivum (summer snowflake) has a wider natural range, taking in Europe (including the British Isles), southwest Asia and northern Iran, and growing in wetter habitats including damp woodland, riversides and swamps. Despite its common name it flowers from April to May, though later than the Spring Snowflake. It is a taller plant than Leucojum vernum, growing to around 60 cm (2.0 ft), but its flowers are smaller and are carried in an umbel of between three and seven. Its fleshy seed pods are inflated, allowing them to be dispersed by flood water. Leucojum aestivum subsp. pulchellum (Salisb.) Briq., native to the western Mediterranean Basin, is smaller: 20 cm (8 in), and flowers 2 weeks earlier, i.e., from mid-March.
In 1807, Richard Anthony Salisbury illustrated two species in The Paradisus Londinensis. He initially used the name Leucojum autumnale for the plant illustrated in plate 21, but when discussing Leucojum pulchellum (now included in L. aestivum), illustrated in plate 74, Salisbury noted the differences between the two species, and considered them sufficient to move Leucojum autumnale into a new genus, Acis. Although some botanists accepted the split between Leucojum and Acis, including Robert Sweet in 1829, most did not; for example, Brian Mathew in 1987 placed all the species in Leucojum. Acis was reinstated in 2004, after it was determined on morphological and molecular grounds that the broadly defined genus Leucojum was paraphyletic, with Acis and a more narrowly defined Leucojum being related as shown the following cladogram.
- Leucojum aestivum L. – summer snowflake or Loddon lily – Europe, Middle East, Caucasus; naturalized in Australia + North America
- Leucojum vernum L. – spring snowflake – southern and central Europe from Spain to Ukraine
The two species of Leucojum have been described as "tough garden plants for damp soils". L. aestivum, the summer snowflake, grows particularly well on clay soils. L. vernum, the spring snowflake, is easy to grow in moist sunny or semi-shady places and flowers along with snowdrops.
Leucojum aestivum 'Gravetye Giant' is a selected cultivar with larger flowers. It is named after Gravetye Manor, an Elizabethan manor house in West Sussex, England, the home of the influential garden writer William Robinson from 1884 until his death in 1935. The house is now a hotel.
Leucojum vernum 'Podpolozje' is a robust cultivar which combines the properties of var. carpathicum with that of the variant ‘vagneri’, i.e., two flowers per stem and yellowish spots on its tepals.
Leucojum aestivum was named the county flower of Berkshire following a 2002 survey by the wild flower and plant conservation charity Plantlife. It was once common in the Loddon Valley, hence its alternative name of the 'Loddon lily'.
- "Leucojum". World Checklist of Selected Plant Families. Royal Botanic Gardens, Kew. Retrieved 2017-05-26.
- Stevens, P.F. "Angiosperm Phylogeny Website: Asparagales: Amaryllidoideae".
- Lledó, Ma D.; Davis, A.P.; Crespo, M.B.; Chase, M.W. & Fay, M.F. (2004). "Phylogenetic analysis of Leucojum and Galanthus (Amaryllidaceae) based on plastid matK and nuclear ribosomal spacer (ITS) DNA sequences and morphology" (PDF). Plant Systematics and Evolution. 246 (3-4): 223–243. doi:10.1007/s00606-004-0152-0. Retrieved 2017-12-04.
- "Genere Leucojum". Altervista Flora Italiana. Retrieved 2017-05-26.
- Linnaeus, C. (1753). "Leucojum". Species Plantarum. 1 (first ed.). p. 289.
- "Leucojum aestivum". World Checklist of Selected Plant Families. Royal Botanic Gardens, Kew. Retrieved 2017-05-26.
- Salisbury, R.A. & Hooker, W. (1805–1808). The Paradisus Londonensis : or Coloured Figures of Plants Cultivated in the Vicinity of the Metropolis. London: W. Hooker (printer D.N. Shury). doi:10.5962/bhl.title.53520. OCLC 1864969.
- "IPNI Plant Name Query Results for Acis". The International Plant Names Index. Retrieved 2014-11-12.
- "Search for Acis". World Checklist of Selected Plant Families. Royal Botanic Gardens, Kew. Retrieved 2017-05-26.
- Mathew, Brian (1987). The Smaller Bulbs. London: B.T. Batsford. ISBN 978-0-7134-4922-8. pp. 119–121.
- "RHS Plant Selector - Leucojum aestivum 'Gravetye Giant'". Retrieved 2013-05-21.
- "RHS Plant Selector - Leucojum vernum". Retrieved 2013-05-21.
- "County flowers". Plantlife. Archived from the original on 2015-04-30.
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