R2101 definitions

Plant descriptions/ definitions

You will need to know the definitions below and 2 examples for each type for the exam. I think it would be easiest to learn examples of plants that you are familiar with since on one past paper, they also asked for a description of the plant which I do not think I saw in the syllabus. I have just put down the examples that I thought of for my notes. It’s probably really important to spell the latin names correctly too.

Herbaceous = a non-woody plant which dies back in winter. Examples are Paeonia lactiflora and Papaver orientale.

Perennial = a non-woody plant living for many years. Can be evergreen or semi-evergreen. [I think that this term can also include trees, but not in terms of the exam, just stick to non-tree plants]. Examples are Hosta and Astilbe chinensis.

Annual = herbaceous plant which completes its lifecycle in one year. A hardy annual can tolerate frost and is sown in situ; example: Calendula officinalis (pot marigold) and Tropaeolum majus (nasturtium). A half hardy annual cannot tolerate much frost and is sown under cover ; example: Gerbera and Salvia splendens . A tender perennial cannot survive frost at all; example: Canna and Capsicum annuum. [Tender perennials did not come up in any of the past papers I did]

Biennial = herbaceous plant that completes lifecycle in 2 years. It grows in the first year and then flowers in the second. Examples: Digitalis purpurea and Daucus carota (carrot).

Bulb = a short stem surrounded by fleshy scale leaves. It reproduces by division of offset bulbils produced by the lateral bud. Examples: Narcissus and Tulipa.

Corms = compressed underground shoots in which the stem is swollen. Division by corms formed around the sides by axillary bud. Examples: Gladiolus and Crocus.

Rhizomes = underground, horizontal stems which store starch. As the stem branches, new rhizomes are formed from lateral buds. Propagate by cutting into suitable sections. Examples: Iris germanica and viola odorata.

Tubers = modified stem with minute scale leaves each with a bud capable of developing into a plant. Example: Solanum tuberosum (potato – this is a stem tuber) and Dahlia (this is a root tuber).

Woody = a plant which is a perennial reinforced with wood produced from secondary xylem. It has a permanent branch structure.

Tree = a woody perennial with a single main trunk rising from the ground. Examples: Quercus robur (Oak tree, deciduous) and Eucalyptus gunnii (eucalyptus, evergreen).

Shrubs = these are woody perennials with either a short main stem, or several stems rising from the ground. Examples: Buddleia davidii (deciduous) and Choisya ternata (evergreen).

Evergreen = retains leaves in winter. Examples: Choisya ternata and Eucalyptus gunnii.

Semi-evergreen = where the plant loses leaves for a short period of time. [this has not come up in the past papers I did.] Examples: Cotoneaster and Hydrangea quercifolia.

Ephemeral = goes through several lifecycles in a year. Examples: Cardamine hirsuta and Capsella bursa pastoris.

Lifecyles

Plants go through different life stages. You will need to be able to define these.

• seed. This is an embryo which will germinate and grow in to a plant if the conditions are right.
• juvenile. This is the period when the plant is growing and putting on leaves etc. It cannot reproduce during this stage. This stage is useful in horticulture since it can be easier to take cuttings from a juvenile plant because of the higher level of growth hormones. The plant form can also differ from the adult form, as in Eucalyptus gunnii.
• adult. The plant is still able to grow at this stage, but is also capable of reproduction, so it forms flowers and fruit.
• senescence. This is where the plant begins to slow down, flowering stops and the leaves may drop. This can be used in horticulture for example, the winter coloured stems of Cornus are used for winter interest.
• death. All living processes have stopped and plant decays.