External Plant Notes

Question 1

Define Radicile

Answer 1

Embryo root in a seed which turns into a taproot.

Often persistent thru life (Quercus robur)

Question 2

Define monocot roots

Answer 2

Fibrous, no taproot, don’t penetrate far into soil.

Starts at base of stem

Not reparable when damaged

Xylem and Phloem: RING

Question 3

Define perennation

Answer 3

Biennial or perennial that stores nutrients in roots/tubers to enable survival between seasons.

STEM TUBERS: produce many tubers (solanum tuberosum)

ROOT TUBERS: derived from one root, not regenerate: Dahlia

RHIZOMES: Phyllostachys aurea

CORMS: Solid tissue at center with immature layers of leaves (Crocus sativas)

Question 4

Parts of roots

Answer 4

Apical meristem: undiff cells capable of cell divisions (tips, roots and shoots)

Root Cap: PRotective cap of parenchyma cells that cover ap mer

Root hairs: absorb water, nutrients, mycorrhizal fungi

Vascular cylinder: Bundles of vasc tissues (x and p) that run within the core of plant stems and roots. KEY TRANSPORT OF NUTRIENTS AND WATER

MY. FUNGI: act like root hairs, increase surface area to help woody plants access nutrients such as phosphorous

Question 5

What is a bud

Answer 5

found on woody plants.

compact package of embryonic shoot consisting of immature leaves and dormant meristem tissue. PROTECTED BUDS

Question 6

Different kinds of buds

Answer 6

Apical bud (TERMINAL) at tip of stem which carries on growth

LATERAL (axillary) small side bud develops into lateral branch.

LEAF SCAR - where leaf falls off.
Can ID a plant from leaf scar

BUD SCALE SCAR: scar remains after bud falls off apical buds.

Question 7

What is bark?

Answer 7

the outer covering of the stems and the roots of woody plants, especially of trees. Its three major components are (1) periderm, (2) cortex, and (3) phloem. The periderm is the layer of the bark that is exposed to the environment

Question 8

What is the purpose of bark on a tree?

Answer 8

Protective coating, epidermis

Good way to identify tree

LENTICELS: Allows for gas exchange and respiration

Betula pendula and Prunus serrulata (BIRCH AND CHERRY)

Question 9

How does growth rings (girdle scars) help?

Answer 9

Show’s where one year’s growth starts and other ends.

Helps for pruning, know how much it has grown in length.

Only works with woody plants with buds.

Question 10

Define bract

Answer 10

Modified leaf with a flower or cluster of flowers in its axil.

A specialized leaf which surrounds flowers, colourful and attracts pollinators: Large bract surrounds small less colourful flowers.

Euphorbia pulcherrima or Bougainvillea

Question 11

What helps to identify plant?

Answer 11

Leaf shape
Bark
Pattern leaf (opposite etc)
Flowers

Question 12

Name some leaf shapes

Answer 12

Entire leaves Cornus sanguinea cv.
Needle Conifer (pine, cedar, spruce)
Linear monocot (Tulipia)
Ovate (Cornus sanguinea cv)
Lanceolate Daphne bholua
Rhomboid: Betula pendula (triangular)

Question 13

What are leaf margins?

Answer 13

Type of edging of leaf
Lobed, smooth or toothed

Question 14

What is leaf veination

Answer 14

Pinnate: Most common veins branch in opp directions thru leaf of leaf.

Palmate: branch from midrib Acer palmatum

Arborescent: Leaf changes as plant matures: Hedera or Eucalyptus

Question 15

What are PERFECT FLOWERS

Answer 15

Have both male and female parts in same flower (Hermaphrodite)

Question 16

What are imperfect flowers

Answer 16

Flowers with only male or female parts, not both. COURGETTE.

Question 17

Define Stamen

Answer 17

Male sexual part of plant which includes the filament and anther

Question 18

Carpel or Pistil

Answer 18

Stigma, style and ovary
Pistil is a collection of carpels or indiv carpel.

Question 19

Sepals

Answer 19

(calyx - plural) Modified leaves that encase developing flowers - (green base)

Question 20

Petals

Answer 20

PETALS: (corolla - plural) dominant feature - colourful Attracts pollinators.

Question 21

Nectary

Answer 21

NECTARIES: at base of petal, holds nectar - not all flowers have this. Roses don’t

Question 22

Perianth

Answer 22

Sepal and PETAL.
Monocots sometimes not visible (Tulip)

Dicots: often visible from BEHIND flower.

Question 23

Stigma

Answer 23

Sticky, receptive surface at end of style. Pollen lands here and grows down style to ovary.

Question 24

Style

Answer 24

Organ that joins stigma to ovary

Question 25

Ovary

Answer 25

Part of the carpel that contains the ovules. DEVELOPS into FRUIT after fertilization.

Question 27

Ovule

Answer 27

Female sex cells which develop into SEEDS after fertilization

Question 28

Anther

Answer 28

Pollen produced here

Question 29

Filament

Answer 29

Stalk that positions anther in best way to disperse pollen.

Question 30

Receptacle

Answer 30

Top of the pedicel that supports and acts as base of the flower

Question 31

Peduncle

Answer 31

floral main axis - main supporting stalk where flower head grows.

Question 32

What is inflorescence

Answer 32

cluster of flowers on a branch or system of branches

Question 33

Types of inflorescence

Answer 33

Panicle Buddleja davidii
Raceme Linaria maroccanna
Umbel Daucus carota
Stalk start at same point
Disk florets Helianthus annus
Spike: Lavandula angustifolia
Catkin: Betula pendula
Spadix: Cordyline australis
Spikelet: Elymus repens
Corymb Achillea millefolium (longer stems reach same height)

Question 34

Raceme

Answer 34

a flower cluster with the separate flowers attached by short equal stalks at equal distances along a central stem. The flowers at the base of the central stem develop first.

Question 35

What are main seed dispersal methods?

Answer 35

Gravity
Wind (parachute - Taraxacum officinale or Wings Acer campestre)
Ballistic
Water Nymphaea
Animals (frugivory) provide fruit for animals to eat; attachment/scattering or INTERNAL seeds germinate once thru gut.

Question 36

What do external structures of a plant tell us about its growing conditions?

Answer 36

Leaf size, texture or colour.

Large soft: Waterside
Very dark leathery: Shade
Tall perennials: fertile soil fighting for light
Deep roots (taproots) drought

Question 37

How do external structure of plant protect from pests/diseases

Answer 37

BARK and THICK LEAVES: Sap sucking and internally fungal infections

SPINES: grazing animals, sap sucking or caterpillars

Question 38

How does external structure help plants to estab and spread?

Answer 38

Tall stems: get above competitors
Lg sideways: shade other plants
Roots that form shoots (Aegopodium podagraria)

Stems root at tip: Buxus sempervirens.

Question 39

Root modifications

Answer 39

Food storage (tubers)
Reproduction (suckers)
Water storage (adventitious for walls and aerial roots for orchids)
Support: Banyan trees grow branches down to ground that support and grow roots.

Question 40

Leaf Modifications

Answer 40

Protection: Spines - Berberis thunbergia
Water storage: succulents
Attract pollinators: BRACTS

Question 41

How can plants be described by their external plant structures?

Question 42

What are the links between external parts of plant and their function?

Answer 42

Root structure linked to food storage

Way leaf arrangement enable efficient photosynthesis

Lenticels in gaseous exchange

Role of flowers and their floral parts

Question 43

How are root structures identified help control measures?

Answer 43

Taproot vs fibrous. Perennial vs annual

Question 44

How do external parts protect stem tissue from pest attack?

Answer 44

Prickles
Spikes
Bark
Cuticle above upper epidermal layer of cells

Question 45

What is a rhizome? State TWO ways in which a rhizome differs from a root.

Answer 45

A rhizome is a stem which runs more or less horizontally at or very near ground level. Roots however go down.

Rhizomes produce shoots and adventitious shoots and so effectively spread the plant - roots do not usually do this, altho in some species they do.

Rhizomes store nutrients and water. Roots primarily absorb water and nutrients from the soil.

Question 46

What are three functions of stems?

Answer 46

a. Stems provide nutrients to roots through photosynthesis and transpiration from the leaves.

b. Stems can place the petiole and flowers in advantageous positions to maximize plant growth. This is why many plants tend to lean towards the maximum sun exposure.

c. Stems, can in some cases, provide extra photosynthesis for the plant, usually when the stem is green.

Question 47

What are the functions of root hairs?

Answer 47

Root hairs increase the surface area of the roots which will provide additional water and minerals for the plant.

Question 48

Describe how external plant structure characteristics can be used to identify a species. Include THREE named examples.

Answer 48

a. LEAF STRUCTURE: Most often we identify plants through their leaves. Monocots, like grasses, daffodils and Iris have long straight linear leaves which grow faster than dicots producing plants faster in the season. Monocot vein structure is parallel. Hostas, a monocot has a broadleaf structure, but the veins are parallel. The plant has adapted to its environment by producing larger leaves for photosynthesis. Roses are compound leaves with a pinnate structure. They have numerous leaflets sprouting from rachis on each leaf.

b. TREE BARK: When a plant is dormant, we often have to look at the structure of the plant, especially when it comes to woody plants like trees. There are two ways to identify trees, either their bark or the buds. Should the bark of a tree have lenticels (narrow horizontal slits) the chances are it’s a member of the Prunus or Betula
family. The buds on the tree can also give some clue as you look at the dormant season twigs. The structure will show either opposite, alternate or a whorl structure.

c. STEMS: Many of the plants we look at during dormant seasons can offer clues through the stem structure. The Leaf scars provide information regarding alternate, whorl or opposite structure. Twining stems clearly show that the plant does not build a strong stem but uses adjacent structures to grow. Additionally the distance between the buds can offer clues regarding the age of the twig and how fast the plant grows each season

d. Each plant will have a unique combination of leaf structure, stem growth and colour Examples include:

The Rosaceae which has an alternate pinnate leaf structure and thorns. In particular the
Rosa canina is a variable climbing, wild rose species native to Europe with either white or pale pink flowers.

The Betula sp.,has a whitish bark and small lenticels which provide gas exchange for the tree. The
Betula populifolia is identifiable by its long, pointed leaves that turn a pale yellow in the Fall. The bark is white with blackish lenticels. It is native to Northern America.

The Hedera helix, is a climbing plant with palmate leaves. Once it has climbed as far as it can, the leaves change to an arborescent phase where they no longer have clinging rootlets. It begins to grow vertically and leaves become rounder. Blossoms can be green, white or yellow, which usually occur after the arborescent phase.

Question 49

Weed control is an issue in almost every garden. Many plants create problems of competition to the plants we want to grow. What are the external characteristics of weed plants that can make them competitive, and therefore problematic? Give one named example from your own experience.

Answer 49

Plants that are rapidly growing, with large leaves or spreading foliage, often tall.

Rapidly growing rhizomes, the ability to grow quickly from rhizomes or often small segments of rhizomes or even roots.

The ability to seed profusely, with seedlings which grow rapidly

Creeping buttercup (Ranunculus repens) with stems that ‘leap frog’ a distance and grow roots when they touch the soil. It can cover ground denying space to smaller garden plants or seedlings.