Transcript Biol316 Plant Form and Function

Announcements
--> WEDNESDAY
1. Lecture cancelled - see Friday Ecology
Seminar instead: 4 - 5 pm NULH (possible
extra credit available)
2. Lab review 2 - 4:30 pm
3. Term papers returned
--> MONDAY - Lecture Midterm and Lab
Practicum
1. Study Guide available on web site Tuesday
Afternoon
Correspondence between flower and fruit
http://w3.dwm.ks.edu.tw/bio/activelearner/35/images/ch35summary.gif
Forming a Seed
1. Fertilization initiates both
seed and fruit
development
2. Seeds develop
from ovules
3. Driest living
plant tissue
(<20% H20)
4. Seed coat resistant and
buoyant
Seed Parts
1. Embryo - grows into sporophyte
2. Integuments (seed coat) protection
3. Endosperm - food reserve
Options for Food Storage in Seed
A.
Endosperm
•
•
•
•
Fusion product of two polar nuclei in ovule
Grows by nuclear division while embryo is dormant
Often 3N tissue
Ranges from solid material to liquid
B. Fleshy seed leaves
C. None
Fruit - Seed Protection and Dispersal
1. Develops from
ovary tissue
2. Associated extracarpellary
structures (petals,
sepals)
3. Fruit wall of ovary
4. Surrounds and
protects the
seed(s)
5. Important in seed
dispersal
6. Initial nutrient
source
Types of Fruits
1. Fleshy - attract animal dispersers move
seeds to new locations after successfully
passing through the digestive system of
the animal
2. Non-fleshy - other mechanisms for seed
dispersal
3. Parthenocarp - fruits developed without
fertilization (typically seedless)
Fruit Layers
1. Ovary wall
often
thickens Pericarp
2. May be
differentiated
into three,
more or less
distinct,
layers
• Exocarp - outermost layer; often epidermis
• Mesocarp - middle layer; varies in thickness
• Endocarp - inner most layer; considerable
variation from one species to another
Classifying Fruits
1. Depends on number of ovaries and the number
of flowers involved formation
2. Classified into three major groups
–
–
–
Simple - from single mature ovary in a single flower
Aggregate - many matured ovaries from a single
flower
Multiple - matured ovaries of several flowers united
into a mass
Figure 3.1: Plant tissue consumed as fruit.
(Coombe, 1976; Kays, 1991)
http://www.fao.org/DOCREP/005/Y2515E/y2515e04.htm
Types of Simple Fruits
A. Simple Fruits - can be
fleshy or dry
(nonfleshy)
B. Nonfleshy fruits can be
A. Dehiscent - split open
when fully mature
B. Indehiscent - do not
split open when mature
Simple Fleshy Fruits
1.
BERRY - layers of pericarp
fused; lots of seeds
1a. Pepo - hard rind (exocarp);
only in Cucurbitaceae (e.g.,
squash)
1b. Hesperidium - leathery
exocarp rind with oil glands
(Citrus); mesocarp white
parenchyma tissue;
endocarp multicellular juice
sac hairs
2. DRUPE - stone fruit, derived
from a single carpel and
containing (usually) one
seed
Coconut - a
specialized
drupe
Simple Fleshy Fruits,
continued
3. POME - Rose family
only; from several
carpels; also example
of an assessory fruit
due to tissues besides
carpel
3a. HIP (accessory fruit)several separate
carpels enclosed
within the fleshy or
semi-fleshy receptacle
Dry Fruits - pericarp dry
at maturity
DEHISCENT
1. FOLLICLE - one
carpel; pod-like
fruit splits along
single suture
2. LEGUME - one
carpel; splitting
along two sutures
Dry Fruits - Dehiscent
continued
3. CAPSULE several
carpels; can
split along
various
sutures
4. SCHIZOCARP fruit splits into
1-seeded
segments, but
carpel does
not split open
Dry Fruits - do not split
at maturity
INDEHISCENT
1. ACHENE - one-seeded fruit;
seed attached to pericarp at
one point only
2. CARYOPSIS - grain; oneseeded fruit; attached to
pericarp at all possible points
Dry Fruits INDEHISCENT continued
3.
SAMARA - one- or twoseeded fruit; pericarp
bearing a wing like
outgrowth (modified
achene)
4. NUT - hard, one-seeded
fruit; generally from
compound ovary; with
the pericarp hard
throughout
Aggregate Fruits
1.
A fruit derived from a
single flower with many
pistils resulting in. many
matured ovaries formed in
a single flower
2.
Each "Fruitlet" is the
product of one carpel.
Individual ovaries called
fruitlets.
Hard to distinguish
between multiple and
aggregate fruit without
knowledge of the flower.
3.
4.
Multiple Fruits
1.
2.
Fruit derived from
several or multiple
flowers clustered along
a common axis.
Typically are accessory
fruits
Accessory Fruits
1. Develop from tissues
surrounding the ovary
2. Generally develop from
flowers that have inferior
ovaries
3. Receptacle or
hypanthium becomes a
part of the fruit
4. Accessory fruits can be
simple, aggregate or
multiple