Dietes bicolor (Yellow Wild Iris)
Plant image

With its unusual flowers, attractive shape and ease of cultivation, the yellow wild iris is a versatile garden plant that is best in large drifts.

Name & classification

Botanical name:
Dietes bicolor

Common names:
Yellow Wild Iris, Peacock Flower (E)
Uintjie, Poublom (A)

Plant family:
Iridaceae
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Plant categories:
Non-herbaceous Perennials; Bulbs, Corms, Rhizomes or Tubers


Name derivation & history:
The name Dietes means "having two relatives" and refers to the relationship between this genus Moraea and Iris (Dietes were once called Moraea - a closely related group - but were separated because Dietes have a rhizome, whereas Moraea have a true corm).

The species name "bicolor" means two-coloured.

Pictures

Features

Leaf habit:
Evergreen

Height:
1 metre

Width:
1 metre

Plant shape:
Dietes bicolor forms dense clumps of erect sword-shaped leaves arranged in flat, narrow fans from a rhizome.

Leaf description:
The leaves are 1 to 2cm wide, light green in colour and have a double central vein. They are arranged in flat fans similar to other members of the iris family.

Spine or thorn description:

Flower description:
The flowers are about 60mm in diameter, flat, light yellow with brown markings and are produced on the ends of much-branched flower stalks. The flowers only last for one day, but because so many buds are produced the plant is almost always in flower from October until January (spring and summer).

The flower of Dietes bicolor is made up of three functional units, each consisting of an outer tepal and a style branch. Each of these units must be entered separately by the pollinating insect (probably a bee). Nectar is secreted at the base of each of the outer tepals. When the insect pollinator pushes itself between the outer tepal and style branch in search of nectar, the pollen is deposited on its back and as it moves from plant to plant it spreads pollen from one flower to the other resulting in pollination.

Flower colour:
Light yellow with brown markings

Flowering months:
October to January (spring and summer)

Fruit description:
The fruit is a club-shaped capsule approximately 25mm in diameter which partially splits to release the seeds.

Other distinctive features:
The plant spreads by means of its modified stems (rhizomes), which are located below the soil surface.

Habitat

Natural distribution:
Dietes bicolor is found naturally in the Bathurst region of the Eastern Cape in South Africa.

Habitat:
It occurs naturally near streams and in marshy places.

Water requirements:
Little water required, but does best with plenty of summer water

Frost tolerance:
Hardy

Light conditions:
Sun; semi-shade; shade

Other Characteristics

Drought resistant
Wind resistant

Edibility & Toxicity

We have no confirmation that any part of this plant is edible
We have no confirmation that any part of this plant is toxic, however we urge caution as this information may be incorrect.

Ecology

Interaction with physical surroundings:
Dietes attract pollinating insects which, in turn, attract various insectivorous birds to the garden.
Attracts birds
Attracts insects

Other information

Uses & Cultural aspects:
It has become a popular landscaping plant due to its reliability and hardiness and is often found in parking areas at shopping centres, schools etc. It can be effectively used in mass plantings, but is also effective in mixed plantings or used as an accent plant alongside a pond or some steps.

Roots of Dietes bicolor were traditionally used as a charm to protect and strengthen the wearer.

Cultivation:
The yellow wild iris is fast growing which makes it ideal for use in areas that need to be established rapidly. Although it occurs naturally near streams and in marshy places, it is also drought resistant and frost hardy. Dietes bicolor forms a large spiky clump, ideal for use as an accent plant near ponds or at the sides of steps, pathways and entrances. Because the plant multiplies rapidly, it can be easily propagated for large scale plantings. Its evergreen, spreading habit makes it suitable for use as a long lasting groundcover. The plant is able to grow easily in very poor soil with little water and can be useful when plants need to be established on poor subsoils as is often the case after earth moving has taken place on building sites. The yellow wild iris is often mass planted on road islands.

The plants also thrive in damp situations and will tolerate light shade, but do better in full sun except in hot inland gardens where partial shade is best. For optimal results plant the yellow wild iris in soil containing plenty of compost and water regularly.

Dietes bicolor can be propagated by dividing the rhizomes of large clumps after the flowering period or in autumn. The seed of the plant germinates readily when sown in spring or autumn in a good, moist seedling medium.

Similar species:
Dietes grandiflora has larger white flowers

Notes:
Of the six species of Dietes that are known, five of them occur in the eastern parts of South Africa with one on Lord Howe island (Dietes robinsoniana). The most primitive of these (according to molecular analysis) is Dietes bicolor followed by Dietes robinsoniana on Lord Howe island. This suggests that Dietes robinsoniana got to Lord Howe island through dispersal from an African origin, although how this could have happened is at present unknown.

Dietes bicolor belongs to the family Iridaceae (iris family). These plants are perennial herbs in the form of either rhizomes or corms. There are about 82 genera and 1700 species belonging to Iridaceae. Over half of the species of Iridaceae occur in South Africa, in 38 genera. Plants in the family Iridaceae have sword-shaped leaves which are arranged in 2 ranks (a row, especially a vertical row). The flowers are regular or irregular with 3 stamens and an inferior ovary.

References:
South African National Biodiversity Institute, South Africa.

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