|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.
Until 2004, the genus Leucojum was treated as including species now placed in Acis. Leucojum when narrowly circumscribed consists of only two species, Leucojum aestivum and Leucojum vernum. Compared to Acis, Leucojum has hollow rather than solid flower stalks (scapes), white flowers with green or yellow marks on both the inner and outer three tepals, flower stems (pedicels) at least as long as the spathes enclosing the inflorescence, and larger seeds, 5–7 mm across. Like the related snowdrops (Galanthus), Leucojum has wider strap-shaped leaves rather than the usually narrowly filiform ones of Acis, 5–20 mm wide in L. aestivum and up to 25 mm wide in L. vernum.
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.
Nine former members of the genus Leucojum, characterized by their narrow leaves, solid stems and unmarked flowers, are now placed in Acis, leaving only two species in Leucojum.
- Leucojum aestivum L. – summer snowflake or Loddon lily – Europe, Middle East, Caucasus; naturalized in Japan, Australia, North America and Uruguay
- Leucojum vernum L. – spring snowflake – southern and central Europe from Spain to Ukraine; naturalised in Japan and parts of the US
Distribution and habitat
Leucojum is native to Europe, except in the north-west, and then through Turkey to Iran. The two species, but particularly L. aestivum, are widely naturalized throughout the world, including in other parts of Europe, Japan, parts of Australia, North America and Uruguay. It prefers damp situations, such as wet meadows and ditches, and shady habitats, such as woods.
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.
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- 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.
- Grey-Wilson, Christopher; Mathew, Brian & Blamey, Marjorie (1981). Bulbs : the bulbous plants of Europe and their allies. London: Collins. pp. 136–137. ISBN 978-0-00-219211-8.
- "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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