Inflorescences

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Inflorescences
Spring 2012
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What is an inflorescence?

• Simpson An aggregate of one or more flowers,
  the boundaries of which generally occur with the
  presence of vegetative leaves below
• Judd et al. 2008 The shoot system which serves
  for the formation of flowers and which is
  modified accordingly

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Look for the flowering zone!
(from Judd et al. 2008)
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Inflorescence development
Determinate the apical meristem of the primary
inflorescence axis terminates in a flower, which
usually matures first with overall maturation
from the apex to the base Indeterminate the
apical meristem of the primary inflorescence
axis does not terminate in a flower, with
maturation going from the base to the apex
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Determinate inflorescences
Fig. 9.35
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scorpioid cyme
cyme
terminal solitary
head
helicoid cyme
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Indeterminate inflorescences
Fig. 9.36
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raceme
spike
spadix
head
panicle
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Determinate or indeterminate types
Also heads can be either.
Fig. 9.37
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Secondary or compound inflorescence types
Fig. 9.38
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Specialized inflorescence types
Fig. 9.39
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Fruits
Spring 2012
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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.

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Ovary wall becomes the pericarp

• ENDOCARP innermost layer
• MESOCARP - middle layer
• EXOCARP - outermost layer
• Each can be modified independently of the others
  (e.g., the endocarp can be stony, the mesocarp
  fleshy, and the exocarp leathery)

pericarp
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exocarp
mesocarp
endocarp
seed
Avocado (Persea, Lauraceae)
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Three main fruit types

• Simple fruit a fruit that develops from a
  single flower
• Aggregate fruit develops from multiple separate
  carpels of a single flower
• Multiple fruit a fruit derived from the
  gynoecia of several closely clustered flowers

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Simple fruits

• Simple fruits fruits developing from a single
  carpel or a compound ovary (2 or more fused
  carpels) (e.g., apple) can be dry or fleshy

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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?

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Indehiscent Dry Fruits
Fig. 9.40
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Achene single-seeded, seed coat not fused to
pericarp
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Utricle achene with the pericarp much larger
than the seed
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Caryopsis Grains singled-seeded, seed coat
fused to pericarp unique to grasses
Wheat (Triticum aestivum)
Maize (Zea mays)
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Samara
Ulmus (Ulmaceae)
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Dry Indehiscent Fruits Nuts
hard-shelled, one-seeded
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Dehiscent Dry Fruits
Fig. 9.41
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Follicle one suture opens
Asclepias (Milkweed, Apocynaceae)
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Legume opens along 2 sutures
Bean Family Fabaceae (Leguminosae)
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Cruciferous Dry Fruits
Silique
Silicle
Mustard Family (Brassicaceae) 2-carpellate, outer
rim (replum), persistent partition (false septum)
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Capsule a fruit formed from 2 or more united
carpels and dehiscing at maturity to release the
seeds
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Loculicidal Capsule
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Septicidal Capsule
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Poricidal Capsule
Papaver (Poppy, Papaveraceae)
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Schizocarp of mericarps
Dill (Apiaceae)
samaroid mericarps Acer (Sapindaceae)
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Fleshy Simple Fruits

• One or more layers of the pericarp
• become fleshywhich one(s)?
• Number of carpels? Number of seeds?
• From a superior or inferior ovary?

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Fleshy Simple Fruits

• Berry Entire pericarp fleshy or exocarp may be
  leathery, one to many seeds
• Drupe - Exocarp mesocarp fleshy, endocarp hard
  (single-seeded)
• Pome Fleshy mesocarp exocarp fused to
  hypanthium/receptacle (Rosaceae)

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Drupe
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Drupe - Coconut
Cocos nucifera (Arecaceae)
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Berry
Capsicum (Solanaceae)
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Berry (Pepo)
Found in the Cucumber Family (Cucurbitaceae) pa
rietal placentation, leathery exocarp
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Berry(hesperidium)
Found in the citrus family (Rutaceae) Leathery
exocarp, fleshy modified trichomes (juice sacs)
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Pome
Rose family (Rosaceae) inferior ovary,
cartilaginous endocarp, fleshy hypanthial tissue
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Three main fruit types

• Simple fruit a fruit that develops from a
  single flower
• Aggregate fruit develops from multiple separate
  carpels of a single flower
• Multiple fruit a fruit derived from the
  gynoecia of several closely clustered flowers

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Aggregate Fruit
Rubus (Rosaceae)
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Aggregate of Achenes
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Three main fruit types

• Simple fruit a fruit that develops from a
  single flower
• Aggregate fruit develops from multiple separate
  carpels of a single flower
• Multiple fruit a fruit derived from the
  gynoecia of several closely clustered flowers

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Multiple fruit of achenes
Platanus (sycamore)
A. Laurent
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Multiple Fruit - Pineapple
Ananas (Bromeliaceae)
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Multiple Fruit Syconium (Fig)
Ficus (Moraceae)