R2101 1.1 – 1.4 Plant Classification & Life Cycles

Question 1

Definition of a conifer

Answer 1

Mostly evergreen

Perennial woody plants with secondary growth

Cones and naked seeds

Needle-shaped or scalelike leaves

Question 2

2 examples of a shrub

Answer 2

• Mahonia japonica*
• Buxus sempervirens*

Question 3

2 examples of a tree

Answer 3

• Fagus sylvatica*
• Betula pendula*

Question 4

Half hardy annual

Answer 4

Life cycle of a year

Survive temperatures down to –5

Can be sown under protection and planted out after all danger of frost is past

• Cosmos* ‘Gazebo’
• Dahlia* ‘Bishop’s Children’
• Zinnia* ‘Purple Prince’

Question 5

Hardy annual

Answer 5

Lives for one year.

Can survive and withstand temperatures below –5, and frost.

E.g. Lathyrus odoratus

• Calendula officinalis* ‘Orange King’
• Nigella damascena* ‘Miss Jekyll’

Question 6

Tender perennial

Answer 6

Lives more than 2 years

Can’t survive temperatures below 1 degree or frost.

• Canna indica*
• Musa ornata*

Question 7

Genus

Answer 7

Above ‘species’, below ‘family’; the generic name that precedes species, written in ital

Characteristics in common, from which further groups can be formed (species)

2 species belonging to same genus cannot produce fertile offspring

Question 8

Species

Answer 8

Basic unit of biological specification

The largest group of organisms that can interbreed to produce fertile offspring

Share set of DNA

Name forms second part of binomial nomenclature

Question 9

e.g. Cultivar

Answer 9

• Cornus alba ‘Sibirica’
• Forsythia x intermedia ‘Lynwood Variety’
• Rosa rugosa ‘Scabrosa’

Question 10

Gymnosperms

Answer 10

• More ancient group
• Mostly consist of trees and shrubs. Perennials. Simpler vascular tissue.
• Flowers unisexual (either male or female but not both).
• Naked seeds – seeds do not have a protective fruit
• Seeds produced in a cone, the female organ.
• Leaves usually needle-like with thick waxy cuticle.

Question 11

Angiosperms

Answer 11

• Vascular plants that produce flowers, which produce seeds which are enclosed within fruits
• Flowers can be unisexual or bisexual
• Woody or herbaceous
• Monocots and dicots
• Flowers display mechanisms for pollination, and seeds and fruits have specific features for effective dispersal.

Question 12

Monocots - e.g.

Answer 12

palms, bananas, sedges, rushes, grasses, irises, lilies, some bamboos, and orchids

Question 13

Dicots - e.g.

Answer 13

• Magnolias, roses, honeysuckles, cacti, mallows, buttercups, teas, laurels, birches, beeches, potatoes and tomatoes, water lilies and stonecrops.
• Four of the most economically important are the Fabaceae (bean family), the Apiaceae (carrot family), the Asteraceae (daisy family) and the Brassicaceae (cabbage family).

Question 14

Monocots

Answer 14

• Flower parts and seed chambers in fruit are normally in threes
• Major leaf veins parallel
• Stem vascular bundles scattered
• Roots are adventitious
• Secondary growth absent

Question 15

Dicots

Answer 15

Two seed leaves

Often grow to a large size as they have cambium tissue in stems which allows secondary growth

Flower parts in multiples of four or five

Major leaf veins reticulated

Stem vascular bundles in a ring

Roots develop from radicle (taproot)

Question 16

Life cycle of plant?

Answer 16

• *Seed**
• *Juvenility** – rapid vegetative growth (useful for propagation); also can be extended by pruning e.g. Fagus sylvatica
• *Adulthood** – reproductive phase – flowers and fruit
• *Senescence** – growth ceases
• *Death**

Question 17

e.g. Annual

Answer 17

• Begonia semperflorens*
• Papaver californica*
• Helianthus annus*
• Lathyrus odoratus*
• Calendula officinalis*
• Nigella damascena*
• Viola x wittrockiana*

Question 18

Define “herbaceous”.

Answer 18

Non-woody, soft growth

No secondary thickening

Generally loses stems and foliage at end of growing season, annuals and biennials

Many herbaceous perennials have swollen underground organs to help them survive and spread each year.

Agapanthus africanus
Ale**cea rosea
Alchemilla mollis

Phlox paniculata (perennial)

Question 19

e.g. Evergreen

Answer 19

Retains leaves in all seasons
Ilex aquafolium
Buxus sempervirens

Question 20

e.g. Biennual

Answer 20

Myosotis sylvatica
Lunaria annua
Alcea rosea

Question 21

Xylem and phloem in mono/dicot root?

Answer 21

Monocot: vascular tissue alternately in an X shape

Dicot: vascular tissue arranged in a ring around the pith

Question 22

Xylem and phloem in mono/dicot stem?

Answer 22

Monocots:

• Vascular bundles randomly scattered throughout the ground tissue.
• The bundles are smaller than in the dicot stem, and distinct layers of xylem, phloem and sclerenchyma cannot be discerned.

Dicots:

• Vascular bundles arranged around the periphery of the ground tissue.
• Xylem tissue located toward the interior of the vascular bundle, and phloem located toward the exterior.
• Sclerenchyma fibres cap the vascular bundles.
• In the centre of the stem is ground tissue.

Question 23

What tissues are the same in mono/dicot root?

Answer 23

Epidermis, cortex, endodermis, outer pericycle

Question 24

What is a seed?

Answer 24

Develops from the ovule after fertilization.

Contains the embryonic plant and the nutritive tissue, either as an endosperm or food stored in the cotyledons.

Angiosperm seeds enclosed in fruit that develops form the ovary wall.

Gymnosperms are ‘naked’ and lack an enclosing fruit.

Covered by a protective layer called the testa.

Resting phase (dormancy) until conditions are suitable for germination.

Question 25

What is juvenility?

Answer 25

Early stage of a plant’s life.

Smaller and lacks ability to reproduce.

Some plants have different form compared to adult. E.g. ivy has lobed, juvenile leaves whereas mature leaves are entire. Gorse has flat juvenile foliage whereas adult is spiny.

Some trees also display juvenility – for example, Fagus sylvatica, will keep young leaves over winter. Pruning a beech hedge – retain the plants at their juvenile stage (brown leaves over the winter).

Question 26

What is adulthood?

Answer 26

Able to reproduce: flower and reproduce

Question 27

What is senescence?

Answer 27

• Plants deteriorate. Between maturity and death.
• The decline of the plant due to physiological change (the decline of cell division and reproduction), environmental stress or pathogenic attack (whole plant).
• It may refer to just one part of the plant or to the whole plant.
• For example, the process of abscission (leaf drop) related to the drop of leaves and fruit.

Question 28

Importance of life cycle on horticulture?

Answer 28

• What is grown, and when; what is available to the customer.
• Prices. Mature plants more expensive. Seed is cheap compared to 3L container grown stock.
• Nurseries may specialise in different stock and become experts at particular stages of the plant life cycle in terms of propagation.
• It is important to know about plant life cycles when using different types of planting schemes.