Download Lab #6B

Lab #6B
Angiosperms
Flowers
• structure of a flower – 4 rings of modified
leaves called flower organs:
– 1. sepals
– 2. petals
– 3. stamens
– 4. carpels
Stigma
Stamen
Anther
Carpel
Style
Filament
Ovary
Petal
Sepal
Ovule
Receptacle
1.
2.
3.
4.
5.
Stigma
Style
Anther
Filament
Sepal
Perfect flowers
• male and female on same plant
–
–
–
–
lilies
dandelions
roses
virtually every fruit and vegetable plant in North America
• tomatoes
dandelion
african violet
apple blossom
Imperfect flowers
• male and female reproductive parts on separate flowers
– but may be on the same plant
– staminate flowers
– carpellate flowers
staminate flowers
Inflorescences
• inflorescences = group of
cluster of flowers arranged
on a stem that is comprised
of a main branch or a
complicated arrangement of
branches
• several types
– raceme - unbranched main
axis, flowers attached by a
pedicel
– spike – unbranched main
axis, directly attached flowers
– panicle – branched main axis
– corymb
– head (flower head) – also
known as a composite flower
Composite flowers
• composite flowers = clusters of many
small flowers called florets – each of
which is a full flower
• chicory, dandelion, chrysanthemum,
yarrow, coreopsis, sunflower, dahlia,
zinnia, goldenrod, aster, lettuce,
thistle and Black-eyed Susan.
• composites are miniaturized flowers
• numerous flowers packed onto a
platform called a receptacle,
• so the sunflower is actually a
collection of hundreds of flowers!
• two kinds of flowers: disk flowers
and ray flowers
• disc flowers – center of the
receptacle
• ray flowers – surround the disc
flowers (look like petals)
ray flowers
disc flowers
Flower ovules
Lilium ovary with ovules
Ovary with ovule
Ovary with ovules
Ovules
Ovule
Ovules
Anthers
Fruit
• composed of an outer wall =
pericarp and the inner placenta with
seeds
– pericarp is made up of an exocarp, a
mesocarp and an endocarp
• e.g. apple – skin = exocarp; flesh =
mesocarp; paper part in the center =
endocarp; seeds
• classified as: simple, multiple or
aggregate
– simple – one carpel or several fused
carpels form the fruit
• e.g apple
– multiple – more than one flower with
female parts
– aggregate – number of separate carpels
form the fruit
Fruits – dichotomous tree
• first division – fleshy or dry
• I. Fleshy
– A. simple (from a single ovary) or B. complex (from more
than one ovary)
• A. simple- drupe (hard endocarp = cherry, olive, coconut), berry
(fleshy endocarp = tomato, grape, peppers, cucumbers), pome
(apples, pears)
• B. complex – aggregate (fruit from many carpels on a single flower
= strawberry, raspberry), multiple (fruit from carpels of many
flowers fused together = pineapple, corn)
• II. Dry
– A. fruits that split open at maturity (more than one seed)
or B. fruits that do not split (one seed)
• A. fruits that split – along one seam (peas, beans and peanuts),
along multiple seams (okra, lilies, poppies)
• B. fruits that don’t split – hard pericarp (acorns, chestnut), thin
pericarp and winged (maples, ash, elm), thin pericarp no wings
(sunflowers, cereal grains, grasses)
Placentation
• ovules develop from the placenta and are attached to the
ovary wall until maturation into seeds
• arrangement of the placenta = placentation
– parietal – ovules on the outer ovary wall or extensions of it
– free central – ovules along a central column or axis
– axile – ovules along a central axis which is connected to the ovary wall
Placentation
Axile placentation
Parietal placentation