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Whorl (botany)
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<p>In botany, a whorl or verticil is a <a href="/facts/Whorled/v0cmNUew">whorled</a> arrangement of <a href="/facts/Leaf/1m6wCNTg">leaves</a>, <a href="/facts/Sepal/rFYnXN4d">sepals</a>, <a href="/facts/Petal/DQMkpRSm">petals</a>, <a href="/facts/Stamen/MzNPVK3D">stamens</a>, or <a href="/facts/Gynoecium/P5qFQMk1">carpels</a> that radiate from a single point and surround or wrap around the stem or stalk. A leaf whorl consists of at least three elements; a pair of <a href="/facts/Opposite_leaves/8xGtgllo">opposite leaves</a> is not called a whorl. </p><p>For leaves to grow in whorls is fairly rare except in plant species with very short <a href="/facts/Plant_stem/QlQWSzV4">internodes</a> and some other genera (<i><a href="/facts/Galium/m7KhHRpe">Galium</a></i>, <i><a href="/facts/Nerium/zJM6fK4H">Nerium</a></i>, <i><a href="/facts/Elodea/5XVeIDaM">Elodea</a></i> etc.). Leaf whorls occur in some trees such as <i><a href="/facts/Brabejum_stellatifolium/zrErwpfR">Brabejum stellatifolium</a></i> and other species in the family <a href="/facts/Proteaceae/0kaj3LaH">Proteaceae</a> (e.g., in the genus <i><a href="/facts/Banksia/2cdsI3g6">Banksia</a></i>). In plants such as these, crowded internodes within the leaf whorls alternate with long internodes between the whorls. </p><p>The <a href="/facts/Morphology_(biology)/Nl3B0myy">morphology</a> of most <a href="/facts/Flower/7gI5Kefw">flowers</a> (called <a href="/facts/Cyclic_flower/6PcgTyAH">cyclic flowers</a>) is based on four types of whorls: </p> <ol><li>The <a href="/facts/Sepal/rFYnXN4d">calyx</a>: zero or more whorls of sepals at the base</li> <li>The <a href="/facts/Petal/DQMkpRSm">corolla</a>: zero or more whorls of petals above the calyx</li> <li>The <a href="/facts/Stamen/MzNPVK3D">androecium</a>: zero or more whorls of stamens, each comprising a filament and an anther</li> <li>The <a href="/facts/Gynoecium/P5qFQMk1">gynoecium</a>: zero or more whorls of carpels, each consisting of an <a href="/facts/Ovary_(botany)/Qug4yDY4">ovary</a>, a <a href="/facts/Stigma_(botany)/JEQ85ChP">style</a>, and a <a href="/facts/Stigma_(botany)/JEQ85ChP">stigma</a></li></ol> <p>A flower lacking any of these floral structures is said to be <i>incomplete</i> or <i>imperfect</i>. Not all flowers consist of whorls since the parts may instead be spirally arranged, as in the family <a href="/facts/Magnoliaceae/VeCra8pL">Magnoliaceae</a>. </p>