A cotyledon is defined as a seed leaf, the first leaf that emerges as the seed germinates. Dicotyledonous plants or less commonly known as Class Magnoliopsida are thought to be the most primitive flowering plants. Similar to gnetophytes, all dicots germinate producing two seed leaves, hence dicotyledons; DI happens to mean two. All dicots have other similar characteristics. For example, nearly all dicots have branching venation, and flower parts in multiples of fours or fives. Common examples of dicots include: roses, oak trees, and dandelions.