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 from the text

Fig from the text

Determinateinflorescences Fig from the text

cyme umbel scorpioid cyme head helicoid cyme terminal & solitary

Indeterminateinflorescences Fig from the text

spadix head panicle spike raceme

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 Each can be modified independently of the others (e.g., the endocarp can be stony, the mesocarp fleshy, and the exocarp leathery) pericarp

Avocado (Persea, Lauraceae) seed endocarp mesocarp exocarp

Fig from the text Fruit diversity

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 SiliqueSilicle 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”; singled- seeded, 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