R2101 – Plant Classification, structure and function

Types of plant

This is the first paper and is the longest at 80 minutes. It covers a lot of things that I (sort of) remember from high school.

The exam covers seed-producing plants (also known as spermatophytes). These are sub-divided in to the gymnosperms and the angiosperms.

Gymnosperms are basically the conifers. The past papers do not seem to ask many questions about these, so I think you just need to know that these produce cones and “naked” seeds (ie: no flowers and no fruit). They are mostly evergreen and woody.

Angiosperms are the flowering plants, and the exam focuses on these. These flowering plants are sub-divided themselves into monocotyledons and dicotyledons. You will need to know these definitions and characteristics – they seem to come up in the exam often.

Monocotyledons

Defined as a plant whose seed produces one seed leaf on germination. Examples are lilies, iris, tulip, hosta and all grasses.

The characteristics are:

• one seed leaf
• narrow leaves with parallel veins
• fibrous roots
• vascular bundles are scattered in the stem, they are not organised in any way
• flower parts are in multiples of 3
• primarily wind pollinated
• very little secondary growth (the stem doesn’t get thicker) and no woody growth.
• the flowers have tepals
• pollen has one pore

Dicotyledons

Defined as a plant whose seed leaf produces two seed leaves on germination. The majority of plants are dicotyledons, including all shrubs and trees.

The characteristics are:

• two seed leaves
• leaves can be of many different shapes, but they are broad and have a network of veins
• tap roots
• vascular bundles are arranged in a ring in the stems and roots
• flower parts in multiples of 4 or 5
• flower has separate petals and sepals
• primarily insect pollinated
• secondary growth forming wood
• pollen has 3 pores