Awn (botany)

Source: Wikipedia, the free encyclopedia.
For other uses, see Awn (disambiguation).
spike
) with awns
Awns on the fruit of an Australian species of grass

In

pappus
.

Awns are characteristic of various plant families, including

grasses (Poaceae
).

A common name for awns includes foxtails, for they tend to stick to animals passing by the plant.

Description

In grasses, awns typically extend from the

three-awns
(Aristida).

In some species, the awns can contribute significantly to photosynthesis, as, for example, in barley.

The awns of wild

frog kick, drill the spikelet as much as an inch into the soil.[1]

Geranium dissectum fruits, one undischarged, two of which have discharged their seed-bearing carpels by flinging out the seed as the awns dry, shrink, and split off elastically
Awns on the carpels of Erodium moschatum that twist as they dry. They might either fling off their seed, or entangle in the coats of animals, or partly bury the seed if they land suitably on soil.

When awns occur in the Geraniaceae, they form the distal (rostral) points of the five

style above the ovary. Depending on the species, such awns have various seed-dispersal functions, either dispersing the seed by flinging it out (seed ejection); flinging away the entire carpel so that it snaps off (carpel projection);[2] entangling the awn or bristles on passing animals (zoochory); or possibly burying the seed by twisting as it lies on soft soil.[3]

References

  1. PMID 17495170
    .
  2. ^ Yeo, P. F. (1984). "Fruit-discharge-type in Geranium (Geraniaceae): its use in classification and its evolutionary implications". Botanical Journal of the Linnean Society 89: 1–36. doi: 10.1111/j.1095-8339.1984.tb00998.x
  3. ^ "PlantZAfrica.com Homepage". www.plantzafrica.com.

External links

Look up awn in Wiktionary, the free dictionary.


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