Monocots and dicots are the two broad groups of flowering plants or angiosperms. Historically, scientists classified plants as monocots or dicots based on distinct differences between them. In modern times, molecular biology and genetics indicate the dicots are not all that similar to each other. Even so, most scientists still classify plants as either monocots or dicots. Here are the differences between monocots and dicots and examples of each group.
Monocots
Monocots (or monocotyledons) are plants which have seed with one cotyledon. When the seed germinates, the embryo has one seed leaf. There are around 65,000 species of monocots. Examples of monocots include grasses, grains, onions, daffodils, coconuts, and orchids. Monocot flowers have three petals or else the flowering parts are in multiples of threes. These plants have fibrous (adventitious) roots. The leaves have stomata in rows on both leaf surfaces and veins that run parallel to each other. The upper surface of some monocot leaves have bulliform cells, which control water loss. Each pollen grain has a single pore or furrow. In the stem, the xylem and phloem vascular bundles are scattered, but they form a ring in the roots.
Dicots
A dicot (or dicotyledon) has seeds which have two cotyledons. The plant embryo has two seed leaves, which differ in appearance from the mature leaves. Dicots are much more abundant than monocots. Approximately 250,000 species of dicots are known. Examples of dicots include beans, peas, carrots, apples, roses, dandelions, daisies, cacti, oaks, and maples. Dicot flowering parts are in multiples of four or five. The plant roots often are taproots. The leaves often have stomata on only one surface (usually the lower one) and branched veins. Each pollen grain has three pores or furrows. In the stem, the xylem and phloem vascular bundles form a ring. In the roots, the xylem is central (often forming an “x” shape), with the phloem between the arms of the xylem. Dicot plants often send out secondary growth, while monocots do not.
Monocots vs Dicots – Summary of Differences
Here is a summary of the differences between monocots and dicots:
| Monocots | Dicots | |
|---|---|---|
| Seed | 1 cotyledon | 2 cotyledons |
| Root | Fibrous | Taproot |
| Leaf | Veins are parallel | Veins are branched |
| Root vascular bundles (xylem and phloem) | Xylem and phloem in a ring | Root phloem between xylem arms |
| Stem vascular bundles (xylem and phloem) | Scattered throughout stem | Arranged in a ring |
| Leaf stomata | Stomata on upper and lower surfaces | Stomata often on one surface (usually lower) |
| Secondary growth | Absent | Often present |
| Pollen | 1 pore or furrow | 3 pores or furrows |
| Flower | Petals in multiples of 3 | Petals in multiples of 4 or 5 |
| Examples | Grasses, corn, grains, lilies, onions, carrots, coconut, daffodils, orchids | Beans, coffee, daisies, maple, tomato, mint, cactus |
References
- Angiosperm Phylogeny Group (2016). “An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV”. Botanical Journal of the Linnean Society. 181 (1): 1–20. doi:10.1111/boj.12385
- Bell, Adrian D. (2008) [1991]. Plant Form. An illustrated guide to flowering plant morphology. Oxford University Press. ISBN 9780881928501.
- Bessey, Charles E. (1915). “The phylogenetic taxonomy of flowering plants”. Annals of the Missouri Botanical Garden. 2 (1/2): 109–164. doi:10.2307/2990030
- Cronquist, Arthur (1981). An integrated system of classification of flowering plants. New York: Columbia University Press. ISBN 978-0-231-03880-5.
- Datta, Subhash Chandra (1988). Systematic Botany (4th ed.). New Delhi: New Age Intl. ISBN 81-224-0013-2.