Flowers

Question 1

What are the main feature of flowering plants?

Answer 1

• Main features:
– vascular tissues
– flowers
– double fertilisation (diploid zygote, triploid endosperm)
– ovules contained in carpel
– fruits
• Gymnosperms: no flowers/carpels/fruits


Question 2

What is the classification of Angiosperms?

Answer 2

• Classification of angiosperms: • traditionally monocotyledons &
dicotyledons
• now (on the basis of molecular biology/DNA fingerprinting)
– monocots are a ‘true’ group – dicots are a ‘mixed bunch’

Question 3

What is the flower made up of?

Answer 3

• The flower
• parts are arranged in whorls
• parts are evolved from leaves
• flowers held on peduncle or pedicle
– peduncle – stalk of single flower or basal stalk of inflorescence
– pedicle – stalk of single flower in inflorescence
• parts on receptacle


Question 4

What are whorls?

Answer 4

• 4 whorls
• Outer two sterile
– Sepals (collectively the calyx) (K)
– Petals (collectively the corolla) (C)
– collectively the perianth (P)
– if no diff. between sepals & petals then tepals
• Inner two reproductive
– Androecium – male reproductive (A) – Gynoecium – female reproductive (G)


Question 5

What about Sepals?

Answer 5

• Sepals:

– usually often leaf-like, thickish, green – protective function

Question 6

What about Petals?

Answer 6

• Petals:
– like sepals but usually thinner and brightly coloured
– pollinator attraction
– can form a tube (fused with free lobes)


Question 7

What are Stamens?

Answer 7

• Stamens
– filament with an anther on the end
– each anther has 4 pollen sacs (in 2 pairs)
– pollen grains within sacs
– pollen grains have a tough resistant outer
coat
– all families and genera and some species can be ID’d by their pollen grains

Question 8

What makes up the Gynoecium?

Answer 8

• Gynoecium
• each flower has one or more carpels
• carpel is a unit of the gynoecium
• pistil (more or less = to carpel)
• consists of stigma, style and ovary
• stigma – pollen grains adhere and germinate
• style – pollen tube grow down thru this to the …
• ovarycontainsovules
• ovules attached to the placenta
• within a loculus (aka locule), (loculi, locules plural)
• ovules develop into seeds after fertilisation

Question 9

What flower types are there?

Answer 9

• Complete flowers – all 4 whorls
• Incomplete – missing 1 or more whorls
• Perfect/bisexual flowers – both ♂ & ♀ in 1 fl.
• Imperfect/unisexual flower – missing either ♂ or ♀
• Hermaphrodite = perfect/bisexual
• Monoecious: separate ♂ & ♀ flowers on one plant
• Dioecious: ♂ & ♀ flowers on different plants
• dioecious great for cross-pollination & gene recomb.


Question 10

Can a perfect flower be incomplete?

Answer 10

• most flowers are perfect
• recipe for self-pollination & inbreeding depression?
• no:
– male and female mature at different times – self incompatibility
• Superior ovary – K, C & A attach below ovary
• Inferior ovary - K, C & A attach above ovary

Question 11

Flower Symmetry?

Answer 11

• Superior ovary – K, C & A attach below ovary

* Inferior ovary - K, C & A attach above ovary

Question 12

How do you identify wind pollinated flowers

Answer 12

• Wind:
– Reducedperianth
– Nobrightattractivecolours
– Noodour,nonectar
– Largeanthers
– Lotsoflight,non-stickypollen
– Anthers on long filaments,hang clear of the flower – Large feathery stigmas
– Only few ovules perf lower

Question 13

How do you identify Bee pollinated flowers?

Answer 13

• Bee:
– Flowersbright,white,yellow,blue,UVguides
– ‘pleasantsmell’
– Nectar usually present
– Limitedpollen,oftensticky
– Often landing platforms present
– Oftenzygomorphic
– Various flower shapes,but no long tubes (are for butterflies,moths)


Question 14

What type of Inflorescences are there?

Answer 14

• Inflorescences:
• panicle – peduncle branched
• spike – flowers sessile
• catkin – like spike but fls of only 1 sex
• raceme – like spike but fls with pedicels
• umbel – pedicels come from one point
• head – sessile flowers on flattened axis