Is it a monocot or a dicot?
An unknown plant is brought to you and your job is to determine whether it is a monocot or a dicot. You observe that the plant has 6 petals and its leaves have parallel veins.
Monocots have one cotyledon or seed leaf and dicots have two. Monocots have a flower which is trimerous--this means that flower parts occur in threes or multiples thereof. There are also parallel veins in monocots. You can expect a flower to have 3,6,9 petals if it is a monocot. Onions have parallel veins and are monocots. Dicots have petals in fours or fives and their veins are reticulate. When looking at a cross-section of a monocot vs. a dicot, there are vascular bundles arranged in a scattered fashion in monocots (think of pepperoni on a pizza) and in dicots, they are in concentric circles. The answer to your question about the unknown plant is that it is a monocot.