Agricultural and horticultural practices involve the use of both monocotyledonous and dicotyledonous plants.
The structural components of monocotyledonous and dicotyledonous plants are examined and the vital role that these components play in physiological and reproduction processes of the plant is also considered.
Environmental conditions and human interaction may also significantly influence physiological processes in monocotyledonous and dicotyledonous plants.
Suggested Practical Activity
Examine external and internal structural components of monocotyledonous and dicotyledonous plants:
- Root nodules
- Vascular bundles
- Photosynthetic cells
- Storage cells
- Seeds and fruit
Microscopic observation used to illustrate the distribution of cell types in roots, stems, leaves, and stomata.
Dicots and monocots differ in germination and plant morphology. See the table
below for the major differences in these two types of angiosperms. In addition
to these traits, it is also the case that monocots tend to be herbaceous (e.g.
grasses and grains) while dicots are ~50% herbaceous and 50% woody species.
|Embryo with single cotyledon
||Embryo with two cotyledons
|Pollen with single furrow or pore
||Pollen with three furrows or pores
|Flower parts in multiples of three
||Flower parts in multiples of four or five
|Major leaf veins parallel
||Major leaf veins reticulated
|Stem vascular bundles scattered
||Stem vascular bundles in a ring
|Roots are adventitious
||Roots develop from radicle
|Secondary growth absent
||Secondary growth often present
It is the difference in seed structure that defines these two groups: dicots
have 2 seeds leaves (cotyledons), while monocots have only 1 seed leaf. Seed
germination also differs between these two groups.
The following images provide more detail on the differences in stem structure
between monocots and dicots. Monocots have vascular tissue in bundles throughout
the stem. In contrast, dicot vascular bundles are arranged in a ring around the
outside of the stem.
Monocot stem (left) and dicot stem (right).
Detail of monocot vascular bundle.
Detail of dicot vascular bundle.
Pollination and flower structure
Although many angiosperms have the potential to self-fertilize, most plants
cross-fertilize. To transfer pollen from flower to flower, angiosperms make use
of wind dispersal and animal pollinators. Animals which pollinate flowers
include insects, birds, and mammals. One of the important functions of flowers
is to attract animal pollinators. Because of this, flower structure, color, and
odor vary dramatically in correlation with the primary pollinators. For example,
flowers which are pollinated by flies smell like rotting meat, while some
flowers pollinated by wasps mimic the appearance of a female wasp (potential
mate). The benefits to pollinators include nutrition from nectar and pollen.
It is often possible to determine what type of pollination/pollinator a plant
uses by the structure, color, shape, and smell of the flower. You should be
familiar with this table: