Tripetala Irises
This is a small group of species and only one,
I. setosa, is found commonly in cultivation. The name
refers to the fact that at first glance these flowers
appear to have only three petals because the standards are so small, reduced sometimes to bristle-like
proportions, and much smaller than the style arms.
- I. setosa
- This iris in the wild is widely distributed over many
cold, wet northern hemisphere regions, from
eastern Asia, through Japan to Alaska and the east
coast of Canada. Its form therefore is extremely
variable. It may reach only 6 in (15 cm) in one
place while attaining 3 ft (90 cm) elsewhere. Wet
meadows, peaty bogs, light woods and shorelines are
where it feels at home, but it is an easy-to-grow
garden plant, in appearance rather similar to
Siberian irises, although unlike them, it tends to be short-lived.
This iris likes a moist acidic soil in sun or semi-shade
and the branched stems bear six or more flowers in
early summer. They are usually blue to purple and
the blade of the falls is very wide, which gives the
bloom a generous spreading appearance. The tall
forms look graceful beside water, though they make
good border plants too, especially in combination
with lighter colored variegated grasses of a similar
height. Smaller forms are great for rock gardens.
It is another of those irises with foliage stained
red at the base. Rhizomes are fleshy and frequently
covered with fiber from the remains of dead leaves - perhaps this is insulation for its cold natural environment.
Named cultivars include 'Kosho-en' with white
flowers and 'Kirigamine' with rich velvety blue-purple flowers.
- I. tridentata (syn I. tripetala)
- This iris likes similar conditions to I. setosa and is a good iris to grow in a
container in water, as long as the rhizome is above water level.
- I. prismatica
- This iris is a lonely species, the only one of its kind and not commonly grown. Native to
North America, where it is found in damp
woodlands and marshy ground along the Atlantic
coast from Nova Scotia to Carolina, it grows in tufts
of thin glaucous leaves and likes moist soil and light shade. This iris has dainty, light violet flowers and grows to
2 ft (60 cm) with a slender wiry stem. There is a white form, I. prismatica 'Alba'.
- I. unguicularis (syn. I. stylosa)
- This iris is
native to stony places in Algeria, Crete, Greece, Syria and Asia Minor.
Flowering begins spasmodically in the fall,
continuing through winter and romps into spring if
it's happy. The flower has virtually no stem, just a
perianth tube that grows about 8 in (20 cm) above the ground. To show them in
all their beauty, it is a good idea to cut back the leaves at the beginning of
winter to allow the flowers to unfold undamaged, as the foliage grows to about
24 in (60 cm). Flowers come
in every shade of blue from pale to deep sky-blue;
some are mauve-violet, and there is also a white
form I. unguicularis 'Alba', as well as a soft pink
flowered variety, 'Starkers Pink'. This iris blooms later than
the species and is smaller, with finer leaves, though
the flowers have broad falls and standards.
I. unguicularis likes well-drained soil, benefits
from an occasional dressing of lime, needs sunny
conditions but is cold-hardy and frost-resistant. Plant it out in spring and
water it frequently until it is well-established. In fact this iris needs ample water
throughout the year, except in summer when it prefers to sunbathe.
This is an easy-care species that doesn't need to
be divided regularly to maintain its flowering and if
you must divide clumps, make sure the divisions are
not too small as they re-establish grudgingly. Left to
its own devices it will re-seed easily. Where parent
plants are affected by a virus, seedlings will be free
of contamination. This is a plant to cherish, both
for its perfume and its early flowering habit.
- I. lazica
- This iris resembles I. unguicularis but is adapted to more humid, damper
areas and can tolerate cooler temperatures. A native of northeastern Turkey and
Georgia, this iris grows on shady sandy banks, often
beneath scrub or bracken. Its flowers are somewhat
somber -deep purple-blue with large upright
standards and pendent falls -and, unlike I. unguicularis, have no perfume. In mild climates it
flowers in winter, but where winters are cold, it waits until early spring.
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