Inflorescences & Fruits
Spring 2010
What is an inflorescence?
• Harris & Harris = The flowering part
of a plant; a flower cluster; the
arrangement of flowers on the
flowering axis
• Judd et al. = The shoot system which
serves for the formation of flowers
and which is modified accordingly
Look for the flowering zone!
Fig. 4.27 from the text
Fig. 4.28 from the text
Determinate
inflorescences
Fig. 4.29 from the text
umbel
scorpioid cyme
cyme
terminal &
solitary
head
helicoid cyme
Indeterminate
inflorescences
Fig. 4.30 from the text
raceme
spike
panicle
head
spadix
Maturation
• An inflorescence matures into an
infructescence.
• An ovary (simple or compound) matures
into the fruit (but may include additional
structures (e.g., hypanthium).
• A fertilized ovule matures into a seed.
Ovary wall becomes the pericarp:
•
ENDOCARP – innermost layer
•
MESOCARP - middle layer
•
EXOCARP - outermost layer
pericarp
Each can be modified independently of the others
(e.g., the endocarp can be stony, the mesocarp fleshy,
and the exocarp leathery)
exocarp
mesocarp
endocarp
seed
Avocado
(Persea, Lauraceae)
Fruit diversity
Fig. 4.31 from the text
Simple vs. multiple fruits
• Simple fruit = a fruit that develops from
a single flower
• Multiple fruit = a fruit derived from the
gynoecia of several closely clustered
flowers
Simple fruits: two types
• “Simple” simple fruits = fruits
developing from a single carpel or a
compound ovary (2 or more fused
carpels) (e.g., apple)
• Aggregate simple fruits = fruits
developing from several separate
carpels of a single gynoecium (e.g.,
blackberry)
Dry Simple Fruits
• Dry at maturity
• Does fruit open (dehisce) or not?
(Dehiscent versus indehiscent)
• Number of carpels?
Number of seeds?
• Are any wings present?
Follicle: one suture opens
Asclepias (Milkweed, Apocynaceae)
Legume: opens along 2
sutures
Bean Family
Fabaceae
(Leguminosae)
Cruciferous Dry Fruits
Silique
Silicle
Mustard Family
Brassicaceae (Cruciferae)
Capsule: a fruit formed from 2 or
more united carpels and dehiscing
at maturity to release the seeds
Loculicidal Capsule
Septicidal Capsule
Poricidal Capsule
Papaver (Poppy, Papaveraceae)
Indehiscent Dry Fruits
Samara
Acer (Sapindaceae)
Achene: single-seeded, seed
coat not fused to pericarp
Caryopsis: “Grains”; singledseeded, seed coat fused to
pericarp; unique to grasses
Wheat
(Triticum aestivum)
Maize (Zea mays)
Dry Indehiscent Fruits: Nuts
hard-shelled,
one-seeded
Fleshy Fruits
One or more layers of the pericarp
become fleshy; may be brightly colored.
If the ovary is inferior, then the
hypanthium may also be involved and it
may be the conspicuously fleshy part of
the fruit.
Fleshy Fruits
• Berry – Entire pericarp fleshy or exocarp
•
•
may be leathery, one to many seeds
Drupe - Exocarp & mesocarp fleshy,
endocarp hard
Pome – Fleshy mesocarp; exocarp
fused to hypanthium/receptacle
(Rosaceae)
Berry
Capsicum (Solanaceae)
Berry
Berry (Pepo)
Found in the
Cucumber Family
(Cucurbitaceae)
Berry
(hesperidium)
Found in the
citrus family
(Rutaceae)
Drupe
Drupe - Coconut
Cocos nucifera
(Arecaceae)
Pome
Aggregate
Fruit
Rubus
(Rosaceae)
Multiple Fruit - Pineapple
Ananas (Bromeliaceae)
Multiple Fruit: Syconium (Fig)
Ficus (Moraceae)
Accessory fruits
Fruit or cluster of fruits in which structures
in addition to the matured gynoecium form
a functional part of the fruit.
Simple accessory fruit: e.g., strawberry
Multiple accessory fruit: e.g., pineapple
Accessory “Fruit” – Aggregate of
Achenes