2.2 Inflorescences Flashcards
Inflorescences - definition
Arrangement of flowers on stem.
Single flower - simple
Clustered - compound
Pedicel - each individual flower stalk
Rachis or peduncle - stalk
Flowers gathered together make large impact to attract pollinators also make landing stage for them to land on and pollinators expend less energy flying from flower to flower.
Spike
Flowers have very short or no pedicel
Flower attached along the long, straight peduncle of inflorescence.
Example: Acanthus mollis
Raceme
Flowers attached to unbranched peduncle by pedicel, usually of equal length.
Oldest flowers are at the base of inflorescence
Example : Digitalis purpurea
Simple Umbel
Flowers attached at pedicels, attached at about the same point at the end of the compound.
Example: Allium genus
Compound umbel
Peduncle produces branches that end at approx. same level, forms flat top, end of these branches arise from common point.
Example Daucus carrots
Differences between umbel and corymb
Umbel - all pedicels are given off from the same point
Corymb - pedicels are attached along unbranched, elongated peduncle - not at same point
Corymb
Pedicels are uneven length
Attached along an unbranched, elongated peduncle
Forms flat topped inflorescence
Example Sambubus nigra
Cyme
Usually flat topped, occasionally rounded top inflorescence
Terminal flower is first individual flower to open
Outer flowers then develop
Example Myosotis
Panicle
Flowers are attached to pedicels, which are attached along the branches arising from the peduncle of the inflorescence
Example: Syringa vulgaris
Capitulum
Flattened peduncle > forms receptacle that bears small, sessile flowers
Known as disc florets surrounded by ray florets
Inflorescence surrounded by one or more whorls of bracts called involucres.
Example Helianthus annulus
Verticillaster
Inflorescence develops from the axis of each leaf.
From main axis a lateral axis arises on which flowers appear in whorls
Example Phlomis fruticosus
