This is a large family of deciduous or evergreen perennials,
many with brightly coloured flowers, that is well represented in
The plants are deciduous or evergreen perennials (rarely shrubs)
with a rhizome or corm (rarely a bulb in some New World and Eurasian
The leaves are usually two-ranked with the blade oriented vertically
to the stem and thus sheathing it at the base. This results in the
characteristic fan-like arrangement found in genera like Iris.
This type of leaf lacks distinct upper and lower leaf surfaces.
In many South African species the leaf has a thickened midrib and
often variously thickened or winged margins that may also be crisped.
In some species the leaves are needle-like with narrow longitudinal
grooves. Species of Moraea are unusual in the family in having
channelled leaves with a distinct upper and lower surface.
flowers are arranged in various ways, either insmall clusters between
large bracts or in a spike (rarely solitary), with each flower held
between two small or large bracts. The flowers are radially or bilaterally
symmetrical with six tepals (petals). These may be similar to one
another or different, usually with the upper larger. They are usually
brightly coloured, sometimes with contrasting spots and stripes
and may be very fragrant. The petals are either separate or joined
at the bottom into a short or long tube. The flowers of many Iridoideae,
such as all Aristea species, last less than a single day
but in most species they last for three or four days.
The three stamens are inserted at the base of the petals or just
within the tube (if present), opposite the outer three tepals. They
are either symmetrically clustered in the centre of the flower when
this is radially symmetrical or arched together under the upper
tepal or onto the lower tepal in bilaterally symmetrical flowers.
In some species of Moraea the stamen filaments are joined
into a tube.
The ovary is inferior (superior in the Tasmanian Isophysis)
with three locules each containing several to many ovules attached
to the centre. Each flower has a single style that usually has three
branches near the tip, each of theses sometimes forked as well.
In some genera (Dietes, Ferraria and most species of Moraea)
the style branches are flattened and petal-like.
The fruit is a dry capsule that usually splits open along three
sides to release the seeds. These are very variable in shape. In
most genera they are tetrahedral or variously angled and without
obvious adaptations for dispersal. Winged seeds adapted to wind
dispersal characterise Gladiolus and Tritoniopsis
and also occur in some species of Hesperantha. Globular seeds
with shiny coats that are relatively long-lived occur in several
genera of Ixioideae. Chasmanthe aethiopica has fleshy seeds
adapted to dispersal by birds and several other species that grow
in more wooded places, like Chasmanthe and some freesias
have reddish or black seeds that mimic fleshy seeds.
Nearly worldwide but rare in tropical lowlands and at high latitudes.
Iridaceae are best represented in southern Africa, especially the
winter-rainfall region in the southwest. Other centres of diversity
are temperate South and Central America (several small genera) and
the Mediterranean (Iris and Crocus). About 1 800 species
distributed among some 65 genera are recognised worldwide, just
over half of them in southern Africa, where 38 genera are known.
In the Cape Floral Region alone 707 species and 27 genera are recorded.
The family is best represented in open, seasonal habitats. The
richest areas for species in southern Africa are the montane grasslands
of eastern South Africa, Swaziland and Lesotho, and the succulent
karoo and fynbos of the Northern and Western Cape. Fewer species
occur in savanna or the semi-arid central karroo, and very few in
The species grow in all sorts of soils, derived from granite, basalt,
dolerite, clay, limestone and sandstone, as well as rarer rocks
like serpentine. Most species favour loamy soils, often among rocks
where drainage is good, but some grow in marshes and others in pure
sand. Species grow from just above the high tide mark (Gladiolus
guienzii) to the top of the interior escarpment at over 3 000
The largest genus in the family is Gladiolus (about 255
species), followed by Iris (about 225 species) and Moraea
(about 200 species). Many species are very localised in occurrence.
In the lowlands of the Western Cape in particular farming and urban
sprawl are threatening many species with extinction.
Name and History
The family name is based on the genus Iris, the largest and
best known genus in Europe. The genus Iris dates from 1753,
when it was coined by Swedish botanist, Carl Linnaeus. Its name
derives from the Greek goddess, Iris, who carried messages from
Olympus to earth along a rainbow, whose colours were seen by Linnaeus
in the multi-hued petals of many of the species.
The family is currently divided into four subfamilies but the results
from DNA analysis suggest that several more should be recognised:
- Subfamily Isophysidoideae contains the single genus
Isophysis, from Tasmania. It is the only member of the
family with a superior ovary and has a star-like yellow to brownish
- Subfamily Nivenioideae contains six genera from South
Africa, Australia and Madagascar, including the only true shrubs
in the family (Klattia, Nivenia
and Witsenia) as well as the only saprophyte (Geosiris).
Aristea is also
a member of this subfamily. It is distinguished by having flowers
in small, paired clusters among large bracts, slender styles that
are divided into three slender branches and nectar (when present)
produced from glands in the ovary walls. The flowers are always
radially symmetrical, with separate tepals (petals) and the rootstock
is a rhizome. See drawing of Aristea
- Subfamily Iridioideae is distributed throughout the
range of the family and contains the large genera Iris
and Moraea. It is the only subfamily that is represented
in South America. The species have flowers in solitary clusters
among large bracts, styles that are often petal-like or crested
and nectar (when present) is produced from glands on the tepals.
Most species have separate petals and the rootstock is usually
a rhizome or rarely a bulb. The flowers are almost always radially
symmetrical. Bobartia, Dietes
and Ferraria belong to this subfamily. See drawing of Ferraria
- Subfamily Ixioideae, which contains nearly
two thirds of the species, is mostly African. This subfamily contains
most of the familiar genera apart from Iris and Moraea,
including Ixia, Gladiolus,
Crocus, Freesia and Watsonia.
It is easily recognised by bearing flowers in a spike-like inflorescence
(sometimes solitary), with the tepals joined into a short or long
tube. Nectar is produced from glands in the ovary wall and is
secreted directly into the base of the floral tube. The flowers
are either radially symmetrical or more usually bilaterally symmetrical
and two-lipped. The rootstock is either a rhizome or more commonly
a corm. Several tribes are recognised in Iridoideae and Ixioideae.
See drawing of Hesperantha
petitiana and Schizostylis coccinea.
Members of Iridaceae occur in a great variety of habitats. About
the only place they do not grow is in the sea itself, although Gladiolus
gueinzii occurs on the seashore just above the high tide mark
within reach of the spray. Most species are adapted to seasonal
climates that have a pronounced dry or cold period unfavourable
for plant growth and during which the plants dormant. As a result
most species are deciduous. Evergreen species are restricted to
subtropical forests or savannah, temperate grasslands and perennially
moist fynbos. A few species grow in marshes or along streams and
some even grow only in the spray of seasonal waterfalls.
The above ground parts (leaves and stems) of deciduous species
die down when the bulb or corm enters dormancy. The plants thus
survive periods that are unfavourable for growth by retreating underground.
This is particularly useful in grasslands and fynbos, which are
adapted to regular burning in the dry season. At this time the plants
are dormant and their bulbs or corms are able to survive the heat
of the fires underground. Veld fires clear the soil surface of competing
vegetation, as well as fertilised it with ash. With the arrival
of the first rains, the dormant corms are ready to burst into growth,
sending up flowers and stems before they can be shaded out by other
vegetation. Many grassland a fynbos irids flower best after fires
and some fynbos species will only flower in the season after a fire.
family has a very diverse pollination ecology. Most species are
pollinated by various species of solitary bees but many are adapted
to pollination by sunbirds. These species typically have red to
orange, trumpet-like flowers that secrete large amounts of nectar.
Other species are adapted to pollination by butterflies and moths,
carrion flies and long-proboscid flies, and even monkey-beetles.
Economic and cultural value
Several genera are important in horticulture, both as cut flowers
and as garden plants. The most important cut flowers are Gladiolus,
Iris and Freesia. In Northern Hemisphere gardens several
species of Iris are grown (especially forms of Iris germanica,
the bearded iris) and various cultivars of Crocosmia,
while in South Africa species of Dietes,
Watsonia, Ixia and Sparaxis are best known. The evergreen
Dietes, with its
tufts of narrow, grass-like leaves and prolific Iris-like flowers
is especially used in commercial plantings.
The genus Crocus is grown commercially as the source of
the spice saffron, which is the dried stigmas of the flowers. These
are harvested by hand, hence the enromous pricve fetched by the
spice. The corms of a few common species of Lapeirousia and
Moraea formed part of the traditional diet of some African
In the Garden
The species vary greatly in their ease of cultivation and in their
cultivation requirements. Generally speaking, species from the east
coast, which has a less seasonal climate, are easiest in gardens.
Species from the summer-rainfall parts require a dry winter resting
period while those from the winter-rainfall region require a cool,
moist winter growing season and a dry summer.
To search for more members of the family Iridaceae on this site.
Enter Iridaceae into the search box below.
- Leistner, O.A.(ed) 2000 Seed plants of southern Africa: families
and genera. Strelitzia 10. NBI. Pretoria.
- Manning, J., Goldblatt, P. & Snijman, D. 2002. The color
encyclopedia of Cape bulbs. Timber Press. Oregon.
Compton Herbarium, Kirstenbosch