R2101 1.1 – 1.4 Plant Classification & Life Cycles Flashcards
Definition of a conifer
Mostly evergreen
Perennial woody plants with secondary growth
Cones and naked seeds
Needle-shaped or scalelike leaves
2 examples of a shrub
- Mahonia japonica*
- Buxus sempervirens*
2 examples of a tree
- Fagus sylvatica*
- Betula pendula*
Half hardy annual
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’
Hardy annual
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’
Tender perennial
Lives more than 2 years
Can’t survive temperatures below 1 degree or frost.
- Canna indica*
- Musa ornata*
Genus
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
Species
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
e.g. Cultivar
- Cornus alba ‘Sibirica’
- Forsythia x intermedia ‘Lynwood Variety’
- Rosa rugosa ‘Scabrosa’
Gymnosperms
- 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.
Angiosperms
- 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.
Monocots - e.g.
palms, bananas, sedges, rushes, grasses, irises, lilies, some bamboos, and orchids
Dicots - e.g.
- 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).
Monocots
- 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
Dicots
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)
Life cycle of plant?
- *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**
e.g. Annual
- Begonia semperflorens*
- Papaver californica*
- Helianthus annus*
- Lathyrus odoratus*
- Calendula officinalis*
- Nigella damascena*
- Viola x wittrockiana*
Define “herbaceous”.
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)
e.g. Evergreen
Retains leaves in all seasons
Ilex aquafolium
Buxus sempervirens
e.g. Biennual
Myosotis sylvatica
Lunaria annua
Alcea rosea
Xylem and phloem in mono/dicot root?
Monocot: vascular tissue alternately in an X shape
Dicot: vascular tissue arranged in a ring around the pith
Xylem and phloem in mono/dicot stem?
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.
What tissues are the same in mono/dicot root?
Epidermis, cortex, endodermis, outer pericycle
What is a seed?
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.
What is juvenility?
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).
What is adulthood?
Able to reproduce: flower and reproduce
What is senescence?
- 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.
Importance of life cycle on horticulture?
- 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.
