A dicot embryo (click to enlarge)

A dicot flower (click to enlarge)

Another dicot flower (click to enlarge)

A dicot life cycle (click to enlarge)

Class Dicotyledonae, the dicots, make up the majority of the angiosperms. There are 170,000 species of dicots, including most of the shrubs and non-coniferous trees. The common name of dicots is due to the presence of two seed leaves - cotyledons, tiny leaves in the plant embryo. During germination, the cotyledons will use their enzymes to digest stored food, allowing initial plant growth.

There are several other distinctive features of dicots. In the leaves, main veins are usually branched, and in the stems of the plant, vascular tissues are arranged in a ring. The flowers of dicots have their petals and other structures in patterns of multiples of four or five. Finally, dicots usually contain a taproot, a single large root that grows deep underneath the plant, and off which grow short root branches.

The life cycles of dicots are similar to those of monocots, the other class of angiosperms, though there are some differences that occur between the germination of the seed and the growth of the plant. In dicots, the first organ to develop is the embryonic root, which is soon followed by the embryonic shoot, the beginning of the above-ground plant. To break through the soil for the first time, a hook forms at the tip of the embryonic shoot, protecting the tip by holding it downward as the shoot grows up through the soil; this prevents breakage or damage fo the delicate tip when it is forced up through the hard, abrasive soil. Once it reaches the surface, the hook will naturally disappear as the tip is attracted by sunlight and grows up in the direction of the sun.

Table courtesy of 21st Century Biology

	Monocot	Dicot
Examples	Chives, corn, palm, pineapple	Arabidopsis, peanuts, spinach
Pollen Structure	Single pored	Three pored
Flower Parts	Multiples of three	Multiples of four or five
Leaf Veins	Parallel- ladder like	Reticulated- net like
Vascular Arrangement	Bundles scattered	Arranged in a ring in the cortex
Secondary Growth	Absent	Present
Root Development	Adventitious w/ taproot	Develops from the radicle w/ fibrous root
Number of Cotyledons	One	Two