''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 North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

Description

''Tiarella trifoliata'' is a perennial

dicotyledon The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, t ...

ous

herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...

that flowers in the late spring. The flowers are bell-shaped, white and solitary forming an elongated, leafless

panicle A panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a panicle are of ...

. The calyx lobes are 1.5–2.5 mm and petals are 3–4 mm. Basal

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

are 15–80 mm long and up to 120 mm wide, trifoliate or palmately 3- to 5-lobed. Cauline leaves are infrequent and much smaller. The typical variety of ''Tiarella trifoliata'' (var. ''trifoliata'') has

petiolate Petiole may refer to: *Petiole (botany), the stalk of a leaf, attaching the blade to the stem *Petiole (insect anatomy) In entomology, petiole is the technical term for the narrow waist of some hymenopteran insects, especially ants, bees, a ...

leaves with three leaflets per leaf (i.e., trifoliate). The cut-leaved foamflower (var. ''laciniata'') also has trifoliate leaves with petioles, but unlike the typical variety, it has deep lobes more than half the length of the leaflet. The one-leaf foamflower (var. ''unifoliata'') has sessile, simple leaves (rarely trifoliate).

Taxonomy

''Tiarella trifoliata'' was first described by the Swedish botanist Carl Linnaeus in 1753. Its type specimen was collected by

Georg Steller Georg Wilhelm Steller (10 March 1709 – 14 November 1746) was a German botanist, zoologist, physician and explorer, who worked in Russia and is considered a pioneer of Alaskan natural history.Evans, Howard Ensign. Edward Osborne Wilson (col.) ...

on Cape St. Elias, Kayak Island, Alaska in 1742, but that specimen is now lost. A specimen collected from Sitka, Alaska has been designated as the neotype for this species. In 1832, William Hooker described two additional species of ''Tiarella'' in western North America (''T. laciniata'' and ''T. unifoliata''), including two hand-drawn illustrations in his description.

John Torrey John Torrey (August 15, 1796 – March 10, 1873) was an American botany, botanist, chemist, and physician. Throughout much of his career, he was a teacher of chemistry, often at multiple universities, while he also pursued botanical work, focus ...

and

Asa Gray Asa Gray (November 18, 1810 – January 30, 1888) is considered the most important American botanist of the 19th century. His ''Darwiniana'' was considered an important explanation of how religion and science were not necessarily mutually excl ...

recognized all three species (''T. trifoliata'', ''T. laciniata'', ''T. unifoliata'') in their treatment of genus ''Tiarella'' in 1840. In 1905,

Per Axel Rydberg Per Axel Rydberg (July 6, 1860 – July 25, 1931) was a Swedish-born, American botanist who was the first curator of the New York Botanical Garden Herbarium. Biography Per Axel Rydberg was born in Odh, Västergötland, Sweden and emigrated to t ...

described ''T. californica'' based on an earlier description of a species thought to belong to genus ''

Heuchera ''Heuchera'' ( or ) is a genus of largely evergreen perennial plants in the family Saxifragaceae, all native to North America. Common names include alumroot and coral bells. Description ''Heuchera'' have palmately lobed leaves on long petiole ...

''. All four species (''T. trifoliata'', ''T. laciniata'', ''T. unifoliata'', ''T. californica'') were included in a taxonomy proposed by Olga Lakela in 1937. Based on Hooker's species description,

William Efner Wheelock William is a masculine given name of Norman French origin.Hanks, Hardcastle and Hodges, ''Oxford Dictionary of First Names'', Oxford University Press, 2nd edition, , p. 276. It became very popular in the English language after the Norman conques ...

renamed ''T. laciniata'' as a variety of ''Tiarella trifoliata'' (var. ''laciniata'') in 1896. Similarly,

Federico Kurtz Federico Kurtz, also known as Fritz (1854–1920), was a German-Argentine botanist. Biography Fritz Kurtz was born in Berlin and earned his doctorate from the University of Berlin in 1879. He relocated to Córdoba, Argentina, and in 1884, took ove ...

renamed ''T. unifoliata'' as ''Tiarella trifoliata'' var. ''unifoliata'' in 1894. ''

Flora of North America The ''Flora of North America North of Mexico'' (usually referred to as ''FNA'') is a multivolume work describing the native plants and naturalized plants of North America, including the United States, Canada, St. Pierre and Miquelon, and Greenla ...

'' recognized the varieties (var. ''laciniata'' and var. ''unifoliata'') in an influential treatment of genus ''Tiarella'' published in 2009. , the varieties (not the species) are widely recognized: * ''Tiarella trifoliata'' ** ''Tiarella trifoliata'' var. ''laciniata'' (synonym: ''T. laciniata'' ) ** ''Tiarella trifoliata'' var. ''trifoliata'' ** ''Tiarella trifoliata'' var. ''unifoliata'' (synonym: ''T. unifoliata'' ) Likewise ''Tiarella californica'' is considered to be a synonym of ''T, trifoliata'' var. ''laciniata''.

Distribution

In western North America, ''Tiarella trifoliata'' prefers shaded, moist, sometimes dense woods up to . It ranges from northern California through western Canada northward to Alaska, and eastward to Montana. Within this region, the varieties of ''T. trifoliata'' have overlapping ranges: * ''Tiarella trifoliata'' var. ''laciniata'': British Columbia; Oregon, Washington * ''Tiarella trifoliata'' var. ''trifoliata'': Alberta, British Columbia; Alaska, California, Idaho, Montana, Oregon, Washington * ''Tiarella trifoliata'' var. ''unifoliata'': Alberta, British Columbia; Alaska, California, Idaho, Montana, Oregon, Washington ''T. trifoliata'' var. ''trifoliata'' and ''T. trifoliata'' var. ''unifoliata'' range north to Alaska, while ''T. trifoliata'' var. ''laciniata'' only ranges as far north as Vancouver Island in British Columbia.Pojar, Jim; MacKinnon, Andy. ''Plants of the Pacific Northwest Coast''. Lone Pine Publishing, 1994, p. 168,

Conservation

The conservation status of ''Tiarella trifoliata'' is globally secure (G5). Each variety is secure as well.

References

Bibliography

* *

External links

*
CalfloraJepson Flora Project (1993): ''Tiarella trifoliata''
{{- trifoliata Flora of California Flora of the Northwestern United States Flora of Western Canada Flora of the Klamath Mountains Natural history of the California Coast Ranges Natural history of the San Francisco Bay Area Plants described in 1753 Taxa named by Carl Linnaeus Garden plants of North America