|Tiarella cordifolia sensu stricto Orange County, NC USA (21 April)|
|Genus:|| Tiarella |
| Tiarella cordifolia |
Tiarella, the foamflowers, is a genus of flowering plants in the family Saxifragaceae. As of October 2022 [update] , the taxonomy of Tiarella in eastern North America is in flux.The generic name Tiarella means "little turban", which suggests the shape of the seed capsules. Worldwide there are seven species, one each in eastern Asia and western North America, plus five species in eastern North America.
Plants of genus Tiarella are perennial, herbaceous plants with short, slender rhizomes. presence or absence of stolons; 2) size and shape of basal leaves; and 3) presence or absence of stem leaves (also called cauline leaves). Two species of Tiarella have stolons (T. austrina, T. stolonifera) while two other species have stem leaves (T. nautila, T. austrina). Plants from the southern Blue Ridge Mountains and southward have relatively large basal leaves with an extended terminal lobe (T. austrina, T. nautila, T. wherryi).Three morphological features are used to distinguish Tiarella species: 1)
The following identification key was published by Guy Nesom in 2021:
1a. Inflorescence a narrow panicle or thyrse (branches with 2–5 flowers), usually with a single axis; petals linear to subulate; styles 2–3 mm long; leaves simple to trifoliolate; western North America
1b. Inflorescence a raceme (branches usually with 1 flower), axis usually single but sometimes branched; petals absent or else present and oblanceolate to elliptic; styles 1 mm or less long; leaves simple; Asia or eastern North America
2a. Petals absent; Asia
2b. Petals present; eastern North America
3a. Plants always with herbaceous, leafy stolons
4a. Leaves usually with obtuse to rounded lobes, terminal lobe not prominently extended; flowering stem very rarely with a small bract; sepals 2.5–3.5 mm long
4b. Leaves usually with acute-acuminate lobes, terminal lobe prominently extended; flowering stem usually with 1–2 leaves or foliaceous bracts; sepals 1.5–2 mm long
3b. Plants without herbaceous, leafy stolons
5a. Leaves usually about as long as wide, usually with obtuse to rounded lobes, terminal lobe not extended; sepals 2.5–3 mm long
5b. Leaves usually longer than wide, usually with acute-acuminate lobes, terminal lobe prominently extended; sepals 1.5–2 mm long
6a. Flowering stem usually with leaves or foliaceous bracts
6b. Flowering stem without leaves or foliaceous bracts
In 1753, Swedish botanist Carl Linnaeus established genus Tiarella by recognizing two species, Tiarella cordifolia and Tiarella trifoliata.A third species, Tiarella polyphylla, was described by David Don in 1825. Together these three species form the taxonomic backbone of the genus. In 1840, in the first critical treatment of Tiarella since Linnaeus, John Torrey and Asa Gray described two new sections:
Olga Lakela highlighted the section names in 1937,but they have since fallen out of favor with botanists, mainly because Tiarella polyphylla is inconsistent with the dichotomy, but perhaps also because there are taxa with leafy flowering stems in both western and eastern North America.
In Asia, the genus is represented by one species (Tiarella polyphylla).In North America, there have been numerous major treatments of genus Tiarella, with taxonomies recognizing from two to six species, some including infraspecific taxa.
|Tiarella trifoliata and related taxa|
(Tiarella sect. Anthonema)
|Tiarella cordifolia and related taxa|
(Tiarella sect. Eutiarella)
|Torrey & Gray 1840.||3||1|
Currently accepted taxonomies are based on three sources:
The treatment in the first source is near-universally accepted,the second is widely recognized, while the third is new and growing in acceptance. A few authorities (with global scope) accept all three.
All names used in this section are taken from the International Plant Names Index, As of October 2022 [update] , POWO accepts 7 species and 3 infraspecies:except where noted. The geographical locations are taken from Plants of the World Online (POWO).
Tiarella is native to Asia and North America. It has been introduced into Norway.
Tiarella polyphylla is an Asian species, ranging from the eastern Himalayas to China, east Asia, and southeast Asia. In China, it is found in moist forests and shady wet places at altitudes from 1,000 to 3,800 meters (3,300 to 12,500 ft).
In western North America, Tiarella trifoliata ranges from California northward to Alaska, and eastward to Montana. trifoliata have overlapping ranges.Within this region, the varieties of T.
In eastern North America, Tiarella cordifolia sensu lato is wide ranging, from northeastern Wisconsin across southeastern Canada to Nova Scotia, extending southward through the Appalachians into Alabama and Mississippi.The range of Tiarella cordifolia sensu stricto is narrowly confined to the East Coast of the United States from Maryland through Virginia and the Carolinas into Georgia.
At least one species of Tiarella occurs in each of 26 provinces and states. Multiple species of Tiarella occur in eight (8) states. Tiarella stolonifera occurs in 22 provinces and states, it being the only species of Tiarella in 17 of those provinces and states. Tiarella cordifolia sensu stricto occurs in just five (5) states, all of which have at least two Tiarella species. The ranges of Tiarella nautila , Tiarella wherryi , and Tiarella austrina overlap in Tennessee, North Carolina, and Georgia.
A disjunct population of Tiarella occurs in Stearns County, Minnesota but botanists believe it was introduced. stolonifera, but evidence is lacking.That population is claimed to be T.
In western North America, Tiarella trifoliata is globally secure (G5).Each variety is globally secure as well.
In eastern North America, Tiarella cordifolia sensu lato is globally secure (G5).It is frequent to common throughout most of its wide distribution but becomes rare at the edges of its range, in Wisconsin and the western Upper Peninsula of Michigan, Nova Scotia, New Jersey, and Mississippi.
Many hybrids are known and cultivated. The following have been given the Royal Horticultural Society's Award of Garden Merit:
Trillium erectum, the red trillium, also known as wake robin, purple trillium, bethroot, or stinking benjamin, is a species of flowering plant in the family Melanthiaceae. The plant takes its common name "wake robin" by analogy with the European robin, which has a red breast heralding spring. Likewise Trillium erectum is a spring ephemeral whose life-cycle is synchronized with that of the forests in which it lives. It is native to the eastern United States and eastern Canada from northern Georgia to Quebec and New Brunswick.
Tiarella cordifolia, the heart-leaved foamflower, is a species of flowering plant in the family Saxifragaceae. The specific name cordifolia means "with heart-shaped leaves", a characteristic shared by all taxa of Tiarella in eastern North America. It is also referred to as Allegheny foamflower, false miterwort, and coolwort.
Symphyotrichum ericoides, known as white heath aster, frost aster, or heath aster, is a species of flowering plant in the family Asteraceae native to much of central and eastern North America. It has been introduced to parts of Europe and western Asia.
Tiarella trifoliata, the three-leaf foamflower, is a species of flowering plant in the family Saxifragaceae. The specific name trifoliata means "having three leaflets", a characteristic of two of the three recognized varieties. Also known as the laceflower or sugar-scoop, the species is found in shaded, moist woods in western North America.
Anaphalis margaritacea, commonly known as the western pearly everlasting or pearly everlasting, is an Asian and North American species of flowering perennial plant in the family Asteraceae.
Symphyotrichum lateriflorum is a species of flowering plant in the aster family (Asteraceae). Commonly known as calico aster, starved aster, and white woodland aster, it is native to eastern and central North America. It is a perennial and herbaceous plant that may reach heights up to 120 centimeters and widths up to 30 centimeters.
Symphyotrichum pilosum is a perennial, herbaceous, flowering plant in the Asteraceae family native to central and eastern North America. It is commonly called hairy white oldfield aster, frost aster, white heath aster, heath aster, hairy aster, common old field aster, old field aster, or steelweed. It may reach 20 to 120 centimeters tall, and its flowers have white ray florets and yellow disk florets.
Canadanthus is a North American monotypic genus of flowering plants in the family Asteraceae. The only species is Canadanthus modestus, commonly known as great northern aster or western bog aster. It is native to most of Canada and to northern parts of the United States.
Tiarella wherryi is a species of flowering plant in the family Saxifragaceae. The specific name wherryi recognizes Edgar Wherry, the botanist who collected some of the first specimens in the early 1930s. Commonly called Wherry's foamflower, it is the southernmost of all species of Tiarella in the southeastern United States, where its range approaches the Gulf Coast in southern Alabama.
Carex austrina, known as southern sedge, is a species of sedge endemic to the southern and central United States.
Symphyotrichum patens, commonly known as late purple aster or spreading aster, is a perennial, herbaceous plant found in the eastern United States.
Symphyotrichum ontarionis is a species of flowering plant in the family Asteraceae native to eastern North America. Commonly known as Ontario aster and bottomland aster, it is a perennial, herbaceous plant that may reach heights of 120 centimeters. Each flower head has many tiny florets put together into what appear as one.
Symphyotrichum potosinum is a species of flowering plant in the family Asteraceae native to Mexico and the U.S. state of Arizona. Commonly known as Santa Rita Mountain aster, it is a perennial, herbaceous plant that may reach heights of 15 to 45 centimeters.
Symphyotrichum eulae is a species of flowering plant in the family Asteraceae endemic to Texas. Commonly known as Eula's aster, it is a perennial, herbaceous plant that may reach 5 to 150 centimeters in height. Its flowers have usually white to bluish or lavender-white ray florets and yellow then reddish to brown disk florets. It was named for Eula Whitehouse, American botanist, botanical illustrator, and plant collector.
Symphyotrichum turneri is a species of flowering plant in the family Asteraceae native to Durango, Mexico.
Tiarella stolonifera is a species of flowering plant in the family Saxifragaceae. The specific name stolonifera means "spreading by stolons", an important characteristic of this species. Known as the creeping foamflower, it has the widest range of any species of Tiarella in eastern North America.
Tiarella nautila is a species of flowering plant in the family Saxifragaceae. The specific name nautila alludes to its sail-like stem leaves. Accordingly, it is sometimes called the sail-leaf foamflower. The species is narrowly endemic to the Blue Ridge Mountains in the southeastern United States.
Tiarella austrina is a species of flowering plant in the family Saxifragaceae. The specific name austrina means "from the south". Being endemic to the southeastern United States, it is sometimes referred to as the southern foamflower. It is one of two species of Tiarella that spread by stolons.
Tiarella polyphylla is a species of flowering plant in the family Saxifragaceae. The specific name polyphylla means "many-leaved". The species is native to Asia, ranging from the eastern Himalayas to China, east Asia, and southeast Asia. It is sometimes called the Asian foamflower.