Iris humilis is a plant species in the genus Iris. It is also in the subgenus of Iris and in the Psammiris section. It is a rhizomatous perennial, with a wide distribution range from Europe to Russia to China, via Mongolia and Kazakhstan. It has sword-shaped leaves, a short stem and yellow flowers with an orange beard. It is cultivated as an ornamental plant in temperate regions.
It once had Iris arenaria as a synonym or as a subspecies. It is a yellow dwarf iris only from central Europe. In some sources it is still listed as a subspecies of Iris humilis.
Iris humilis is very similar in form to Iris mandshurica (another Psammiris species), which leaves curve to one side, but it is a shorter plant.[1]
It has thick creeping rhizome,[2] [3] [4] which is branched,[3] and about 1 cm in diameter.[5] The rhizome has the remains of last seasons leaves on the top.[1]
It has bluish-green,[1] [3] gray-green,[6] [7] or light glaucous green,[8] [9] sword shaped or lanceolate,[2] basal leaves.[5] [6] They can grow up to 5- long,[7] [8] [9] and 0.2–0.7 cm wide,[8] [10] [11] They have incurving tips,[8] [11] and they disappear in summer, after flowering.[9]
It has a simple dwarf (or short stem),[12] [13] that can grow up to between 5- tall.[14] [15] [16]
The stems have 2–3 spathes (leaves of the flower bud), which are lanceolate and are (scarious) membranous at the top of the leaf.[3] [8] They have short,[3] 7.5mm long pedicels (flower stalks).[8]
The stems hold between 1 and 3 flowers,[17] [18] [10] in late spring,[3] [11] [13] between April and June.[8] [12] [18] The flowers only last for a day,[18] but they sometimes repeat the display.[12]
The vanilla scented,[18] flowers are 3- in diameter,[9] [11] [18] come in shades of yellow,[16] [18] [19] including bright yellow.[8] [15] [17]
The flower buds are normally green, that have a slight tinge of bronze.[8]
It has 2 pairs of petals, 3 large sepals (outer petals), known as the 'falls' and 3 inner, smaller petals (or tepals), known as the 'standards'.[5] [20] The falls are oblong shaped, and 35mm long and 1.2 cm wide.[8] They are veined brown or purple brown.[6] [9] [19] They have a central orange beard.[11] [14] [17] The shorter,[8] [10] standards are 30mm long and 0.3 cm wide.[8] The standards are not erect and this gives the flower a flattish appearance.[10]
It has a 1 cm long ovary and a 0.5 cm long, funnel shaped perianth tube.[8]
It has styles that are shorter than the petals,[10] about 2.5 cm long, which have short narrow crests.[8]
The anthers are cream with green-black edging and the pollen is greenish coloured.[8] After the iris has flowered, in August,[3] it produces an elliptical seed capsule,[1] which is about 3 cm long.[8] The capsules dehisce (split open), below the apex.[8] Inside the capsules, are wrinkled, light brown,[1] or brown,[3] pyriform (pear-shaped) seeds.[8] They have flat creamy-white aril (or appendage).[8]
As most irises are diploid, having two sets of chromosomes, this can be used to identify hybrids and classification of groupings.[20] It is normally published as 2n=22.[9] [10] [16]
There has been several counts, over the years including 2n=27, Krogulevich 1978, 2n-24, Sokolovskya & Probatova, 1986, 2n=28, Starobudtsev & Mironova, 1990, 2n=28, Malakhova, 1990, 2n=28 Malakhova & Markova, 1994. As Iris flavissima 2n=22, Doronkin.[14] This shows two separate entities.[14]
Since Iris arenaria has a count of 2n=22,[21] this means that Iris flavissima is a synonym of Iris arenaria and 2n=27 or 2n=28 are the true counts of Iris humilis.
It is pronounced as (Iris) EYE-ris (humilis) HEW-mil-is.[15]
It has the common name of sand iris.[6] [15] Although this name normally refers to Iris arenaria, which was formerly once thought to be a subspecies of Iris humilis, it is now a separate species in its own right.[21] Iris humilis is also known as low iris,[1] [22] and yellow iris.[2] [12] [22] Note, that Iris pseudacorus is also commonly known as the 'yellow flag' or 'yellow iris' as well.
It is known as Sand-Schwertlilie (meaning sand iris) in Germany.[23]
The Latin specific epithet humilis refers to low growing or dwarfish.[7] [24]
It was first published and described by Johann Gottlieb Georgi in 'Bemerkungen einer Reise im Russischen Reich' (Bemerk. Reise Russ. Reich) Vol.1 page196 in 1775.[25] [26]
Georgi described from specimen plants from near to Lake Baikal, (it was called originally Iris flavissima).[26] This is now classified as a synonym of Iris humilis.
It was also published by Karl H. Ugrinsky in 'Fedde's Report. Spec. Nov., Beihefte' Vol.14 in 1922.[14]
In 1808, Bieberstein called a plant (from the Caucasus mountains) Iris humilis, in 'Fl. Taur.-Caucas' Vol.1 on page 33. It was later changed (due to Georgi's earlier publishing) and re-classified as a synonym of Iris pontica Zapal.[14] It was verified by United States Department of Agriculture and the Agricultural Research Service on 4 April 2003, then updated 2 December 2004. It is an accepted name by the RHS.[27]
It is native to a wide distribution area, including temperate regions of Asia and Europe.[5] [9]
It is found in Europe,[18] [19] within the countries of Austria,[8] [9] [10] Czechoslovakia,[9] [10] Hungary,[9] [10] [17] and Romania.[9] [10] However, some or most of these plants could be Iris arenaria, which also has a distribution area in central and eastern Europe.
It is found within the Siberian region,[16] [17] of the Russian Federation,[12] [16] [19] in the states of Buryatia, Chita, Irkutsk, Magadan, Primorye and Tuva. It is also found in Kazakhstan (formerly part of Russia).
Within Asia, it found in China,[3] [4] [27] within the Chinese provinces, of Heilongjiang, Jilin, Nei Monggol, Ningxia and Xinjiang,It is also found in Mongolia,[12] [16] and Japan.[1] [3] [27]
It is listed with Iris glaucescens, Iris lactea, Iris ruthenica, Iris sibirica, Iris tenuifolia and Iris tigridia being found in the Altai-Sayan region (where Russia, China, Mongolia and Kazakhstan come together).[28]
It grows in calcareous sandy and stony (or rocky) areas,[6] [8] including (mountain and hill) slopes,[4] [5] meadows,[4] [5] steppes,[2] [4] and on the edges of birch forests,[2] [4] or pine forests,[1] and beside river banks.[2]
They can be found at an altitude of 200feet-1500feetft (-ft) above sea level.[8]
The iris is rare in various regions,[4] [6] [10] especially in European Russia and Ukraine.[10]
It is listed in the Red Book of Omsk and Tyumen regions (of Siberia).[1] [3] [4]
Many populations of Iris humilis exist in protected reserves including, Azas, Baikal-Lensky, Baikal, Barguzinsky, Sokhondinsky and Ubsunur.[1] [4]
It is hardy to between USDA Zone 1 and Zone 6.[10] [15] It survives in Siberia, so is cold resistant.[1]
It prefers to grow in well-drained soils,[7] [17] it prefers soils containing sand.[6] [18]
It can tolerate mildly acidic or mildly alkaline soils (PH levels between 6.1 and 7.8),[15] including those with lime.[18]
It can tolerate positions in full sun or partial shade.[15] [18]
It has average water needs during the growing season,[15]
The leaves can be damaged by rust fungi.[3]
It can be grown in rock gardens,[1] [7] including rock screes,[17] but needs plenty of space.[8]
It is rarely grown in the UK.[13] To grow in the UK, William Rickatson Dykes recommends to plant the iris, on a 5 cm layer of sand, over garden soil with added leaf mould (or compost).[8]
In 1812, it was grown in gardens near Moscow.[26] It was then tested at botanic gardens in St. Petersburg, Barnaul, Novosibirsk and Chita.[1]
It can be propagated by division (of the rhizome), or by seed growing.[8] [15]
In the wild, some habitats generate poor seed and vegetative propagation.[3]
The plant needs to be hand pollinated (in the UK) to create seed.[8]
Seeds are collected from the dry pods/capsules, when the seeds are ripe.[15]
Seeds need cold stratification, to germinate. They germinate very slowly. In the lab, seeds do not exceed a germination rate of 30%.[3]
Seeds should be sown in trays, in a cold frame or unheated greenhouse.[15]
Germinated seedlings, can produce flowers in the second year of growth.[8]
Iris humilis cultivars include; 'Borzeana', 'Dahurica', 'Flavissima', 'Flavissima Orientalis', 'Flavissima Phylospatha', 'Stolonifera' 'Transuralensis' and 'Umbrosa'.[14]
Like many other irises, most parts of the plant are poisonous (rhizome and leaves), if mistakenly ingested can cause stomach pains and vomiting. Also handling the plant may cause a skin irritation or an allergic reaction.[15]
The rhizomes can be used as part of a Tibetan herbal medicine to regulate menstruation. A powdered form of the rhizome can be used for sepsis and infections.[2]