|Flowers showing crimson stigmas|
Crocus sativus, commonly known as saffron crocus or autumn crocus, is a species of flowering plant in the iris family Iridaceae. A cormous autumn-flowering cultivated perennial, unknown in the wild, it is best known for the culinary use of its floral stigmas as the spice saffron. Human cultivation of saffron crocus and the trade and use of saffron have endured for more than 3,500 years and span different cultures, continents, and civilizations.
The plant is most commonly known as the saffron crocus. The alternative name autumn crocus is also used for species in the Colchicum genus, which are not closely related but strongly resemble the true crocuses; in particular, the superficially similar species Colchicum autumnale is sometimes even referred to as meadow saffron. However, the true crocuses have three stamens and three styles, while colchicums have six stamens and one style; and belong to a different family, Colchicaceae. Colchicums are also toxic, making it particularly crucial to distinguish them from the saffron crocus.
Crocus sativus develops as an underground corm, which produces leaves, bracts, bracteole, and the flowering stalk. It generally blooms with purple flowers in the autumn. The plant grows about 10 to 30 cm high.
Saffron crocus is a triploid with 24 chromosomes (2n = 3x = 24), making the plant sexually sterile due to its inability to pair chromosomes during meiosis. Its most probable ancestor is the wild species Crocus cartwrightianus. Although C. thomassi and C. pallasii are still being considered as potential predecessors or genetic contributors, these hypotheses have not been successfully verified by chromosome and genome comparisons.
It is thought that the domesticated saffron crocus most likely arose as a result of selective breeding from the wild C. cartwrightianus in the southern portion of mainland Greece. An origin in Western or Central Asia, although often suspected, is not supported by botanical research.
The stigmas of the flower are used as the culinary spice saffron. Depending on the size of harvested stigmas, the flowers of between 50,000 and 75,000 individual plants are required to produce about 1 pound of saffron; each corm produces only one or two flowers, and each flower produces only three stigmas. Stigmas should be harvested mid-morning when the flowers are fully opened.
As a sterile triploid, C. sativus is unknown in the wild and relies upon manual vegetative multiplication for its continued propagation. Because all cultured individuals of this plant are clonal, there is minimal genetic diversity from the single domestication event, making it quite hard to find cultivars with new, potentially beneficial properties, let alone combine them by breeding. Cultivars of saffron are nevertheless produced by a number of means:
- Clonal selection. Any plant with a desirable mutation is kept and further grown. This is the traditional approach.
- Mutation breeding. Mutagenesis can be used to cause a wide range of mutations to select from. The traditional clonal process follows.
- Sexual reproduction. Breeding for desirable features is much easier in fertile plants.
- Although the plant is not self-fertile, some wild relatives can be successfully cross-pollinated with saffron pollen in vitro and form seeds. This creates fertile diploid plants containing genomic material from C. sativus, allowing new traits to be explored via further cross-pollination.
- Chromosome doubling could in principle also create a fertile hexaploid plant. Such a change may be possible via colchicine.
Corms of saffron crocus should be planted 10 cm (4 in) apart and in a trough 10 cm (4 in) deep. The flower grows best in areas of full sun in well-drained soil with moderate levels of organic content. The corms will multiply after each year, and each corm will last 3–5 years.
Illustration from Köhler's Medizinal-Pflanzen (1897)
Flower's profile, Serra de Casteltallat, Catalonia, Spain
- "The Plant List: A Working List of All Plant Species". Retrieved 23 April 2015.
- "Crocus sativus". Germplasm Resources Information Network (GRIN). Agricultural Research Service (ARS), United States Department of Agriculture (USDA). Retrieved 23 April 2015.
- Bowles, E. A. (1952). A Handbook of Crocus and Colchicum for Gardeners. D. Van Nostrand Company, Inc. p. 154.
- "Colchicum autumnale | meadow saffron/RHS Gardening".
- Kafi, M.; Koocheki, A.; Rashed, M. H.; Nassiri, M., eds. (2006). Saffron (Crocus sativus) Production and Processing (1st ed.). Science Publishers. ISBN 978-1-57808-427-2.
- Mollazadeh, Hamid "Razi's Al-Hawi and saffron (Crocus sativus): a review". Iranian Journal of Basic Medical Sciences, Dec 2015.
- Saxena, R. (2010), "Botany, taxonomy and cytology of Crocus sativus series", AYU, 31 (3): 374–81, doi:10.4103/0974-8520.77153, PMC 3221075, PMID 22131743
- Rubio-Moraga, A; Castillo-Lopez, R; Gomez-Gomez, L; Ahrazem, O (23 September 2009). "Saffron is a Monomorphic Species as Revealed by RAPD, ISSR and Microsatellite Analyses". BMC Research Notes. 2 (189): 189. doi:10.1186/1756-0500-2-189. PMC 2758891. PMID 19772674.
- Harpke, Dörte; Meng, Shuchun; Rutten, Twan; Kerndorff, Helmut; Blattner, Frank R. (2013). "Phylogeny of Crocus (Iridaceae) based on one chloroplast and two nuclear loci: Ancient hybridization and chromosome number evolution". Molecular Phylogenetics and Evolution. 66 (3): 617–627. doi:10.1016/j.ympev.2012.10.007. PMID 23123733.
- Schmidt, Thomas; Heitkam, Tony; Liedtke, Susan; Schubert, Veit; Menzel, Gerhard (2019). "Adding color to a century-old enigma: multi-color chromosome identification unravels the autotriploid nature of saffron (Crocus sativus) as a hybrid of wild Crocus cartwrightianus cytotypes". New Phytologist. 222 (4): 1965–1980. doi:10.1111/nph.15715. ISSN 1469-8137. PMID 30690735.
- Nemati, Zahra; Blattner, Frank R.; Kerndorff, Helmut; Erol, Osman; Harpke, Dörte (1 October 2018). "Phylogeny of the saffron-crocus species group, Crocus series Crocus (Iridaceae)". Molecular Phylogenetics and Evolution. 127: 891–897. doi:10.1016/j.ympev.2018.06.036. ISSN 1055-7903. PMID 29936028. S2CID 49409790.
- Grilli Caiola, M. (2003). "Saffron Reproductive Biology". Acta Horticulturae. ISHS. 650 (650): 25–37. doi:10.17660/ActaHortic.2004.650.1. S2CID 89990377.
- Blattner, Frank R.; Kerndorff, Helmut; Gemicioglu, Almila; Harpke, Doerte; Nemati, Zahra (1 February 2019). "Saffron (Crocus sativus) is an autotriploid that evolved in Attica (Greece) from wild Crocus cartwrightianus". bioRxiv: 537688. doi:10.1101/537688.
- Mathew, B. (1977). "Crocus sativus and its allies (Iridaceae)". Plant Systematics and Evolution. 128 (1–2): 89–103. doi:10.1007/BF00985174. JSTOR 23642209. S2CID 7577712.
- Hill, T (2004). The Contemporary Encyclopedia of Herbs and Spices: Seasonings for the Global Kitchen (1st ed.). Wiley. p. 273. ISBN 978-0-471-21423-6.
- "Saffron Farming Information Guide". AgriFarming. 8 August 2015.
- Alsayied, NF; Fernández, JA; Schwarzacher, T; Heslop-Harrison, JS (September 2015). "Diversity and relationships of Crocus sativus and its relatives analysed by inter-retroelement amplified polymorphism (IRAP)". Annals of Botany. 116 (3): 359–68. doi:10.1093/aob/mcv103. PMC 4549961. PMID 26138822.
- Shokrpour, Majid (2019). "Saffron (Crocus sativus L.) Breeding: Opportunities and Challenges". Advances in Plant Breeding Strategies: Industrial and Food Crops. pp. 675–706. doi:10.1007/978-3-030-23265-8_17. ISBN 978-3-030-23264-1. S2CID 208574298.
- Aqayef, Yusof; Fathi, Mohammad; Shakib, Ali Mohammad (2007). Investigation of possibility of obtaining hexaploid saffron forms through treatment of plants by colchicine (Report) (in Persian). Agricultural Biotechnology Research Institute of Iran.
- "Growing and Harvesting Saffron Crocus". White Flower Farm.
- Media related to Crocus sativus at Wikimedia Commons