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Crocus
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==Description== [[File:328 Crocus sativus L., C. vernus Wulf.jpg|thumb|''Crocus sativus'' & ''C. vernus'', [[AmΓ©dΓ©e Masclef]],<br /> Atlas des plantes de France, 1891|alt=Illustration of two crocus species from 1891]] [[File:A3c85202570a-CROCUS SATIVUS L.jpg|thumb|Crocus sativus, with ovary sectioned|alt=Botanical illustration of crocus sativus including vertical and crosssection of ovary]] === General === ''Crocus'' display the general characteristics of family [[Iridaceae]], which include basal cauline (arising from the aerial stem) leaves that sheath the stem base, [[hermaphrodite]] flowers that are relatively large and showy, the perianth petaloid with two whorls of three tepals each and septal nectaries. The flowers have three stamens and a gynoecium of three united carpels and an inferior ovary, three locules and axile placentation with fruit that is a loculicidal capsule.{{sfn|Goldblatt et al|1998|pp=295β296}} ''Crocus'' is an [[acaulescent]] (lacking a visible lower stem above ground) diminutive seasonal cormous (growing from [[corm]]s) [[Perennial plant|herbaceous perennial]] [[geophytic]] genus.{{sfn|Meerow|2012|p=23}} The corms are symmetrical and [[globose]] or [[Glossary of botanical terms#oblate|oblate]] (round in shape with flatted tops and bottoms), and are covered with tunic leaves that are fibrous, membranous or [[coriaceous]] (leathery). The corms produce fibrous [[root]]s, and contractile roots which adjust the corms depth in the soil, which may be pulled as deep as {{convert|20|cm|in|0}} into the soil.{{sfn|Goldblatt et al|1998}}{{sfn|Zhao et al|2004}} The roots appear randomly from the lower part of the corm, but in a few species, from a basal ridge.{{sfn|Goldblatt et al|1998|p=297}} === Leaves === Plants produce several basal linear bifacial green [[leaves]] that arise from the corms. These are [[Adaxial (botany)|adaxially]] (upper surface facing axis) flat or channelled with pale median stripes, while the opposite (abaxial) surface is strongly keeled, with two grooves on either side. The leaves have a distinctive shape in cross-section, being boat-shaped with two lateral arms with margins recurved inwardly towards the central ridged keel, forming the sides of the "boat". The keel may be square or rectangular, but is lacking in ''C. carpetanus''. The pale central stripe is caused by [[Ground tissue|parenchymatous]] cells which lack [[chloroplast]]s and may contain air spaces.{{sfn|Rudall|Mathew|1990}} The leaves are from {{convert|5 to 30|mm|in|frac=32}} wide and {{convert|10 to 118|cm|in|0}} long. The leaf-like [[bracts]] are membranous, while the smaller bracteoles are either membranous or absent.{{sfn|Goldblatt et al|1998}}{{sfn|Zhao et al|2004}} The leaf bases are surrounded by up to 5 membranous sheaths called [[cataphylls]], a specialised leaf. The bases of the cataphylls form the corm tunic, and their number varies from 3 to 6, and enclose the true leaves (euphylls), bracts, bracteoles and flowering stalk.{{sfn|Kafi et al|2018}}{{sfn|Kerndorff et al|2015}} === Flowers === The number of [[Peduncle (botany)|peduncles]] ([[flower]] [[plant stem|stems]]) vary from one to several and remain underground, emerging only at the fruiting stage, bearing flowers that are solitary or several, so that a true [[Scape (botany)|scape]] is absent. The flowers are [[pedicellate]] (attached to the peduncle by a short subterranean pedicel stalk). The pedicel is sometimes subtended (below pedicel) by a membranous, sheathing [[prophyll]] (leaf-like structure).{{sfn|Goldblatt et al|1998}}{{sfn|Zhao et al|2004}} The showy, salver to cup-shaped, single or clustered [[actinomorphic]] flowers taper off into a narrow tube; the flowers emerge from the ground, and can be white, yellow, lilac to dark purple, or [[Variegation|variegated]] in [[cultivar]]s. The flower tube is long, cylindrical and slender, expanding apically. The [[floral tube]] is long and narrow with 6 lobes in 2 [[Whorl (botany)|whorls]]. The [[perianth]] is 3+3 (3 sepals+3petals) and [[gamophyllous]] (with fused segments). The [[tepal]] whorls are similar, equal or subequal with a smaller inner whorl, and cupped to outspread. The bracts are membranous, but the inner ones are sometimes lacking.{{sfn|Goldblatt et al|1998}}{{sfn|Zhao et al|2004}}{{sfn|Mabberley|1997}} The 3 [[stamen]]s are erect and linear and inserted in the throat of the perianth tube, with anthers shorter than the filaments. [[Pollen]] grains are inaperturate (apertures absent) but sometimes spiraperturate (spiral shaped).{{sfn|Goldblatt et al|1998|p=307}} Each flower has a single [[Stigma (botany)|style]] which is [[exserted]] (projecting beyond the [[Corolla (flower)|corolla]] tube) and slender distally with three to many branches. The branches are highly variable, being short or long, and simple, bifurcate (dividing in two) or multifid and sometimes distally flattened. The inferior [[Ovary (botany)|ovary]] has 3 carpels with [[axile placentation]]. It remains underground, and as the [[seed]]s ripen, the [[Pedicel (botany)|pedicel]] (stem of the flower) grows longer so the [[fruit]] is above the soil surface.{{sfn|Goldblatt et al|1998}}{{sfn|Zhao et al|2004}}{{sfn|Ali|Mathew|2011}} === Fruit and seed === The fruit is a small membranous [[Capsule (botany)|capsule]], ellipsoid or oblong-ellipsoid in shape and the many [[seed]]s are globose to ellipsoid. The seed surface is highly variable, including [[:wikt:papillate|papillate]] (covered in small protuberances), [[digitiform]] (finger-like) and other epidermal cell types. In some species the seeds are [[arillate]], with fleshy appendages. Crocus seeds have both inner and outer [[seed#seed coat|integuments]] and in some species the outer epidermis may display long papillae. [[Embryo-sac]] development is Polygonum type. [[Dehiscence (botany)|Dehiscence]] (splitting of the capsule to release the seed) is of the [[loculicidal]] type in which it splits through the wall of the locules leaving the septa that separate them intact.{{sfn|Goldblatt et al|1998|pp=306,309β310}}{{sfn|Mabberley|1997}}{{sfn|Koocheki|Khajeh-Hosseini|2020}} === Karyology === ''Crocus'' has extensive [[aneuploidy]] (abnormal number of chromosomes), with some uncertainty as to the base [[chromosome number|number of chromosomes]]. The chromosome numbers shows extreme variability, ranging from 2n=6 to 2n=70 even within a single species.{{sfn|Harpke et al|2013}}{{sfn|Goldblatt et al|1998|p=307}} === Phytochemistry === The Iridaceae contain a wide range of [[phenolic compounds]]. However, [[6-Hydroxyflavone]]s are found only in ''Crocus'', which is also [[characterised]] by the presence of [[crocin]]s, water-soluble yellow [[carotenoid]]s, in the floral tissues. Crocin is a [[diester]] of [[crocetin]], responsible for the colour of the styles and stigma of ''C. sativus'', and hence saffron.{{sfn|NCBI|2022a}}{{sfn|NCBI|2022b}} A few species contain [[mangiferin]], a {{chem name|glucosylxanthone}}.{{sfn|Goldblatt et al|1998|p=311}}{{sfn|Mohtashami et al|2021}} While the flowers may vary dramatically between species, there is little variation in the leaves,{{sfn|Harris|2022}} but sufficient variability in corm tunics that they may be used as an aid in differentiating [[taxa]].{{sfn|Serviss et al|2016}} :{| style="background-color:transparent; margin-left: auto; margin-right: auto;" |-valign="middle" |{{multiple image | header = ''Crocus'' structures | align = center | direction = | total_width= 800| float = |perrow=4 | image1=Crocus sieberi - tricolor.jpg| caption1 = [[Corm]]s with net-like papery tunic| alt1 = Crocus corms| width1={{#expr: (150 * 1900 /1425) round 0}} | image2=Krokus (Crocus) met dauwdruppels 02.JPG| caption2=Closed flower with leaves |alt2= Flower with leaves | width2={{#expr: (150 * 1500 /1155) round 0}} | image3=Crocus vernus 20150308.jpg| caption3= Flower with 3 stamens surrounding central style and stigma|alt3= Flower of Crocus vernus | width3={{#expr: (150 * 1500 /1155) round 0}} | image4=Crocus-sp.-4637.jpg| caption4= 3 stamens and style |alt4= 3 stamens and style| width4={{#expr: (150 * 1500 /1155) round 0}} | image5=Krokus (Crocus) 03.JPG| caption5= Central stigma in opening flower|alt5= Stigma seen in centre of opening flower | width5={{#expr: (150 * 1500 /1155) round 0}} | image6=Krokus (Crocus) 07.JPG| caption6= Exserted style & trifid stigma projecting above corolla|alt6=Style and stigma projecting above petals of flower | width6={{#expr: (150 * 1500 /1155) round 0}} | image7=Crocus (146424425).jpeg| caption7= Lateral view|alt7= Side view of flower showing stamens and style projecting above corolla| width7={{#expr: (150 * 1500 /1155) round 0}} | image8=Crocus sp., capsules (2).jpg| caption8= Capsules (seedpods) with seeds|alt8= Crocus seedpods| width8={{#expr: (150 * 1500 /1155) round 0}} }} |[[File:Crocusplant.jpg|thumb|none|270px|alt=Photograph of whole crocus plant from roots to flower]] |- |}
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