| Krameria | |
|---|---|
 | |
| K. lappacea | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Zygophyllales |
| Family: | Krameriaceae Dumort.[1] |
| Genus: | Krameria Loefl. |
| Species | |
17; see text | |
| Synonyms[2] | |
| |
Krameria is the only genus in the familyKrameriaceae, of which any of the approximately 17–18 species.[2][3] The genus is named after the Austrian botanistJohann Georg Heinrich Kramer (1684-1744).[4]
The species are commonly known asrhatany,ratany orrattany. Rhatany is also the name given tokrameria root, a botanical remedy consisting of the dried root of para rhatany (Krameria argentea) or Peruvian rhatany (Krameria lappacea).
The biological action of rhatany is caused by theastringentrhataniatannic acid, which is similar totannic acid.[5] Infusions have been used as a gargle, a lozenge, especially when mixed withcocaine,[5] as a localhemostatic[5] and remedy fordiarrhea. When finely powdered, the dried roots furnished a frequent constituent oftooth powders. The powdered roots have also served, especially inPortugal, to colorwines ruby red.[citation needed] The root bark contains an almost insoluble free red substance called ratanhia red.
Krameria are found across theAmericas where they grow in habitats ranging from arid deserts to subtropical savannas. They are perennial hemiparasitic shrubs that simultaneously photosynthesize and collect nutrients from the root systems of other plants. They have parasitic organs calledhaustoria which puncture foreign roots, forming a bulbous-shaped nutrient pathway between the two organisms.[6]The flowers have two specialized fleshy petals calledelaiophores that produce a lipid which is collected by bees of the genusCentris as they pollinate the flowers. This an obligate pollination relationship, and Krameriaceae is one of elevenextant lineages of oil-flowers.[7]
Krameria was first collected by European botanists in the 1750s during an expedition in northern South America byPehr Löfling. The new taxa was originally placed inLinnaeus' Tetrandria Monogynia, meaning flowers with four stamens and one pistil.[8] Since its initial collection, there have been 17 new species ofKrameria described, the most recent of which,Krameria bahiana, was in 1987.[9]
Krameria exhibits a high degree of morphological divergence from otherangiosperms. This divergence, exemplified by root parasitism and specialized pollination structures, is driven by coevolutionary relationships with insects and other plants. Due to its distinct morphology,Krameria was a "problem taxon"[10] for taxonomists until the 21st century.
Previously allied with thePolygalaceae and theFabaceae, genetic analyses[11] in 1993 and 2000 showed that Krameriaceae is most closely related toZygophyllaceae. This placement had never before been considered by taxonomists due to the morphological differences between the two families.
Within the family, there are two major clades, each with a North and South American subclade.[12] This phylogeny suggests two distinct geographical radiation events between the Americas.
Currently, 17 species are accepted:[2]
