Inflorescence

Inflorescence

Inflorescence • An inflorescence may be defined as a cluster of

flowers,• all flowers arising from the main stem axis or

peduncle:

cyme

• Solitary

just one flower on the peduncle

• Spadix - is the characteristic inflorescence of the remarkable

arum family (Araceae). - It consists of a thickened, fleshy axis (spike) bearing

clusters of sessile, apetalous, unisexual flowers. - The small unisexual flowers are packed together along

the lower region of an erect, phallus-like central spike, typically with male flowers above the female.

- The upper region of the spadix is usually devoid of flowers.

- Male (staminate) flowers consist of numerous stamens packed together,

- while female (pistillate) flowers consist of numerous individual pistils.

- Individual flowers are reduced to a single stamen or pistil (gynoecium).

- The spadix emerges from a vase-shaped or funnel-like modified leaf or spathe which is often brightly colored.

- The spadix of some arums emits a putrid odor that attracts carrion flies for pollination.

• Raceme - This

inflorescence has an unbranched main axis and all the pedicels of the flowers are more or less the same length.

Other Raceme

Sweet pea (Lathyrus odoratus) Chinese hat (Holmskioldia sp.)

• Umbel - The peduncle of  this type of inflorescence bears all

of the pedicels at its apex.

Hydrangea (Hydrangea macrophylla) Lantana (Lantana sp)

• Compound Umbel

- The peduncle bears a number of primary pedicels at its apex. These do not bear flowers but a number of secondary pedicels at their apices which in turn bear the flowers.  Frangipani (Plumeria rubra)

• Spike

- This inflorescence type has a long, unbranched main axis which bears flowers which have no pedicels or very short pedicels.

Silver oak (Grevillea robusta)

Quiver tree (Aloe dichotma)

Gladiolus (Gladiolus sp.)

Red hot poker (Kniphofia sp.)

• Head (capitulum) - which do not have pedicels

- are grouped together on the top of a peduncle

which may be flattened or rounded.

- Daisies (Asteraceae) are a good example

- outer flowers may have one very large petal

- In other families the whole inflorescence may

be surrounded by bracts e.g. the Proteas.

- This gives the impression that the whole

structure is a single flower but it may infact be

hundreds of flowers grouped together.

Examples:

King protea (Protea

cynaroides) Daisy species

Mimosa sp. Pincushions (Leucospermum sp.)

• A Corymb - The main axis of this

inflorescence type is elongated and unbranched as in a raceme, but the pedicels of the flowers are of unequal length so that the entire structure appears flat-topped. Examples include hawthorn, the apple and dogwood.

Crataegus calpodendron

HawthornHawthorn

Hydrangea corymb (group of flowers displayed as a disc)

Difference of corycomb, cyme and umbel

• Spikelet -like a spike, but

with the flowers and inflorescence subtended by specialized bracts. Usually applied to the grass family (Poaceae)

• Verticil or Whorl-

-The flowers are borne in a tight circle at each node

• PaniclePanicle The main

axis has branches which are in turn rebranched

Inflorescence Types