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Dicotyledon
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<p>The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the <a href="/facts/Flowering_plant/E5eGYIvY">flowering plants</a> (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, that the <a href="/facts/Seed/a4xGSLxJ">seed</a> has two embryonic leaves or <a href="/facts/Cotyledon/cX8ntUF2">cotyledons</a>. There are around 200,000 <a href="/facts/Species/oDg6b96r">species</a> within this group. The other group of flowering plants were called <a href="/facts/Monocotyledon/mXCuuCYo">monocotyledons</a> (or monocots), typically each having one cotyledon. Historically, these two groups formed the two divisions of the flowering plants. </p><p>Largely from the 1990s onwards, <a href="/facts/Molecular_phylogenetics/FysplHP5">molecular phylogenetic</a> research confirmed what had already been suspected: that dicotyledons are not a group made up of all the descendants of a common ancestor (i.e., they are not a <a href="/facts/Monophyly/pD8Yrrn6">monophyletic</a> group). Rather, a number of lineages, such as the <a href="/facts/Magnoliids/YcslSG6b">magnoliids</a> and groups now collectively known as the <a href="/facts/Basal_angiosperms/JczzowAg">basal angiosperms</a>, diverged earlier than the monocots did; in other words, monocots evolved from within the dicots, as traditionally defined. The traditional dicots are thus a <a href="/facts/Paraphyly/tmTWjACz">paraphyletic</a> group. </p><p>The <a href="/facts/Eudicots/exlS0I93">eudicots</a> are the largest monophyletic group within the dicotyledons. They are distinguished from all other flowering plants by the structure of their <a href="/facts/Pollen/eqRP052I">pollen</a>. Other dicotyledons and the monocotyledons have <a href="/facts/Monosulcate/eqRP052I">monosulcate</a> pollen (or derived forms): grains with a single sulcus. Contrastingly, eudicots have <a href="/facts/Pollen/eqRP052I">tricolpate</a> pollen (or derived forms): grains with three or more pores set in furrows called colpi. </p>