1. Inflorescences
Spring 2012

2. 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 = The shoot system which serves for the formation of flowers and which is modified accordingly

3. Look for the flowering zone!
(from Judd et al. 2008)

4. 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

5. Determinate inflorescences
Fig. 9.35

6. scorpioid cyme
cyme
terminal &
solitary
head
helicoid cyme

7. Indeterminate inflorescences
Fig. 9.36

8. raceme
spike
spadix
head
panicle

9. Determinate or indeterminate types
Also heads can be either.
Fig. 9.37

10. Secondary or compound inflorescence types
Fig. 9.38

11. Specialized inflorescence types
Fig. 9.39

12. Fruits
Spring 2012

13. 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.

14. 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

15. exocarp
mesocarp
endocarp
seed
Avocado
(Persea, Lauraceae)

16. 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

17. 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

18. 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?

19. Indehiscent Dry Fruits
Fig. 9.40

20. Achene: single-seeded, seed coat not fused to pericarp

21. Utricle – achene with the pericarp
much larger than the seed

22. Caryopsis: “Grains”; singled-seeded, seed coat fused to pericarp; unique to grasses
Wheat
(Triticum aestivum)
Maize (Zea mays)

23. Samara
Ulmus (Ulmaceae)

24. Dry Indehiscent Fruits: Nuts
hard-shelled,
one-seeded

25. Dehiscent Dry Fruits
Fig. 9.41

26. Follicle: one suture opens
Asclepias (Milkweed, Apocynaceae)

27. Legume: opens along 2 sutures
Bean Family
Fabaceae
(Leguminosae)

28. Cruciferous Dry Fruits
Silique
Silicle
Mustard Family (Brassicaceae)
2-carpellate, outer rim (replum), persistent partition (false septum)

29. Capsule: a fruit formed from 2 or more united carpels and dehiscing at maturity to release the seeds

30. Loculicidal Capsule

31. Septicidal Capsule

32. Poricidal Capsule
Papaver (Poppy, Papaveraceae)

33. Schizocarp of mericarps
Dill (Apiaceae)
samaroid mericarps
Acer (Sapindaceae)

34. Fleshy Simple Fruits One or more layers of the pericarp
become fleshy—which one(s)?
Number of carpels? Number of seeds?
From a superior or inferior ovary?

35. 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)

36. Drupe

37. Drupe - Coconut
Cocos nucifera
(Arecaceae)

38. Berry
Capsicum (Solanaceae)

39. Berry (Pepo) Found in the Cucumber Family (Cucurbitaceae):
parietal placentation,
leathery exocarp

40. Berry (hesperidium) Found in the citrus family (Rutaceae):
Leathery exocarp, fleshy modified trichomes (juice sacs)

41. Pome Rose family (Rosaceae): inferior ovary, cartilaginous
endocarp, fleshy hypanthial tissue

42. 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

43. Aggregate Fruit
Rubus
(Rosaceae)

44. Aggregate of Achenes

45. 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

46. Multiple fruit of achenes
Platanus (sycamore)
A. Laurent

47. Multiple Fruit - Pineapple
Ananas (Bromeliaceae)

48. Multiple Fruit: Syconium (Fig)
Ficus (Moraceae)