iris (Iris spp.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Two species of Genus Iris have been documented as occurring in Facquer
County - Iris pseudacorus L. (pale yellow iris) and Iris verna L. (dwarf
violet iris). However, this information (taken from the Atlas of Virginia

Flora database) does not include the wide variety of garden/ornamental

cultivars that are available for home use, and, sometimes "escape" into

more natural environments. Iris observed in Sky Meadows State Park are probably such "escaped" cultivars (e.g., "blue" iris); in addition, the long established introduced pale yellow iris (Iris pseudacorus, see below) is

also present. Further research is necessary to establish the specific species/

cultivars of Genus Iris in Sky Meadows. What follows is a general discus-

sion of Genus Iris.

 

Iris is a genus of 260-300 species of flowering plants with showy flowers.
It takes its name from the Greek word for a rainbow, referring to the wide
variety of flower colors found among the many species. As well as being

the scientific name, iris is also very widely used as a common name for

all Iris species, though some plants called thus belong to other closely

related genera. A common name for some species is 'flags', while the

plants of the subgenus Scorpiris are widely known as 'junos', particularly

in horticulture.

 

The genus is widely distributed throughout the north temperate zone.
Their habitats are considerably varied, ranging from cold and montane
regions to the grassy slopes, meadowlands and riverbanks of Europe, the
Middle East and northern Africa, Asia and across North America.

 

Irises are perennial herbs, growing from creeping rhizomes (rhizomatous
irises), or, in drier climates, from bulbs (bulbous irises). They have long,
erect flowering stems, which may be simple or branched, solid or hollow,
and flattened or have a circular cross-section. The rhizomatous species
usually have 3–10 basal, sword-shaped leaves growing in dense clumps.
The bulbous species have cylindrical, basal leaves.

 

The inflorescences are fan-shaped and contain one or more symmetrical
six-lobed flowers. These grow on a pedicel or lack a footstalk. The three
sepals, which are spreading or droop downwards, are referred to as "falls".
They expand from their narrow base, which in some of the rhizomatous
irises has a "beard" (a tuft of short upright extensions growing in its mid-
line), into a broader expanded portion ("limb"), often adorned with veining,
lines or dots. The three, sometimes reduced, petals stand upright, partly
behind the sepal bases. They are called "standards". Some smaller iris
species have all six lobes pointing straight outwards, but generally, limb
and standards differ markedly in appearance. They are united at their
base into a floral tube that lies above the ovary (known as an inferior
ovary). The styles divide towards the apex into petaloid branches; this
is significant in pollination.

 

The iris flower is of special interest as an example of the relation between
flowering plants and pollinating insects. The shape of the flower and the
position of the pollen-receiving and stigmatic surfaces on the outer petals
form a landing-stage for a flying insect, which in probing the perianth for
nectar, will first come in contact of perianth, then with the stigmatic
stamens in one whorled surface which is borne on an ovary formed of three
carpels. The shelf-like transverse projection on the inner whorled underside
of the stamens is beneath the over-arching style arm below the stigma, so
that the insect comes in contact with its pollen-covered surface only after
passing the stigma; in backing out of the flower it will come in contact only
with the non-receptive lower face of the stigma. Thus, an insect bearing
pollen from one flower will, in entering a second, deposit the pollen on the
tigma; in backing out of a flower, the pollen which it bears will not be rub-
bed off on the stigma of the same flower.

 

The iris fruit is a capsule which opens up in three parts to reveal the
numerous seeds within.

 

 

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